Cutis

The Diagnosis: Netherton Syndrome

A punch biopsy from the right lower back supported the clinical diagnosis of ichthyosis linearis circumflexa. The patient underwent genetic testing and was found to have a heterozygous mutation in the serine protease inhibitor Kazal type 5 gene, SPINK5, that was consistent with a diagnosis of Netherton syndrome.

Netherton syndrome is an autosomal-recessive genodermatosis characterized by a triad of congenital ichthyosis, hair shaft abnormalities, and atopic diatheses.^1,2 It affects approximately 1 in 200,000 live births^2,3; however, it is considered by many to be underdiagnosed due to the variability in the clinical appearance. Therefore, the incidence of Netherton syndrome may actually be closer 1 in 50,000 live births.¹ The manifestations of the disease are caused by a germline mutation in the SPINK5 gene, which encodes the serine protease inhibitor LEKTI.^1,2 Dysfunctional LEKTI results in increased proteolytic activity of the lipid-processing enzymes in the stratum corneum, resulting in a disruption in the lipid bilayer.¹ Dysfunctional LEKTI also results in a loss of the antiinflammatory and antimicrobial function of the stratum corneum. Clinical features of Netherton syndrome usually present at birth or shortly thereafter.¹ Congenital ichthyosiform erythroderma, or the continuous peeling of the skin, is a common presentation seen at birth and in the neonatal period.² As the patient ages, the dermatologic manifestations evolve into serpiginous and circinate, erythematous plaques with a characteristic peripheral, double-edged scaling.^1,2 This distinctive finding is termed ichthyosis linearis circumflexa and is pathognomonic for the syndrome.² Lesions often affect the trunk and extremities and demonstrate an undulating course.¹ Because eczematous and lichenified plaques in flexural areas as well as pruritus are common clinical features, this disease often is misdiagnosed as atopic dermatitis,^1,3 as was the case in our patient.

Patients with Netherton syndrome can present with various hair abnormalities. Trichorrhexis invaginata, known as bamboo hair, is the intussusception of the hair shaft and is characteristic of the disease.³ It develops from a reduced number of disulfide bonds, which results in cortical softening.¹ Trichorrhexis invaginata may not be present at birth and often improves with age.^1,3 Other hair shaft abnormalities such as pili torti, trichorrhexis nodosa, and helical hair also may be observed in Netherton syndrome.¹ Extracutaneous manifestations also are typical. There is immune dysregulation of memory B cells and natural killer cells, which manifests as frequent respiratory and skin infections as well as sepsis.^1,2 Patients also may have increased levels of serum IgE and eosinophilia resulting in atopy and allergic reactions to various triggers such as foods.¹ The neonatal period also may be complicated by dehydration, electrolyte imbalances, inability to regulate body temperature, and failure to thrive.^1,3

When there is an extensive disruption of the skin barrier during the neonatal period, there may be severe electrolyte imbalances and thermoregulatory challenges necessitating treatment in the neonatal intensive care unit. Cutaneous disease can be treated with topical therapies with variable success.¹ Topical therapies for symptom management include emollients, corticosteroids, calcineurin inhibitors, calcipotriene, and retinoids; however, utmost caution must be employed with these therapies due to the increased risk for systemic absorption resulting from the disturbance of the skin barrier. When therapy with topical tacrolimus is implemented, monitoring of serum drug levels is required.¹ Pruritus may be treated symptomatically with oral antihistamines. Intravenous immunoglobulin has been shown to decrease the frequency of infections and improve skin inflammation. Systemic retinoids have unpredictable effects and result in improvement of disease in some patients but exacerbation in others. Phototherapy with narrowband UVB, psoralen plus UVA, UVA¹, and balneophototherapy also are effective treatments for cutaneous disease.1 Dupilumab has been shown to decrease pruritus, improve hair abnormalities, and improve skin disease, thereby demonstrating its effectiveness in treating the atopy and ichthyosis in Netherton syndrome.⁴

The differential diagnosis includes other figurate erythemas including erythema marginatum and erythrokeratodermia variabilis. Erythema marginatum is a cutaneous manifestation of acute rheumatic fever and is characterized by migratory polycyclic erythematous plaques without overlying scale, usually on the trunk and proximal extremities.⁵ Erythrokeratodermia variabilis is caused by heterozygous mutations in gap junction protein beta 3, GJB3, and gap junction protein beta 4, GJB4, and is characterized by transient geographic and erythematous patches and stable scaly plaques; however, double-edged scaling is not a feature.¹ Acrodermatitis enteropathica is an autosomal-recessive disorder caused by mutations in the zinc transporter SLC39A4. Cutaneous manifestations occur after weaning from breast milk and are characterized by erythematous plaques with erosions, vesicles, and scaling, which characteristically occur in the perioral and perianal locations.6 Neonatal lupus is a form of subacute cutaneous lupus erythematosus. Typical skin lesions are erythematous annular plaques with overlying scaling, which may be present at birth and have a predilection for the face and other sun-exposed areas. Lesions generally resolve after clearance of the pathogenic maternal antibodies.⁷

The Diagnosis: Netherton Syndrome

A punch biopsy from the right lower back supported the clinical diagnosis of ichthyosis linearis circumflexa. The patient underwent genetic testing and was found to have a heterozygous mutation in the serine protease inhibitor Kazal type 5 gene, SPINK5, that was consistent with a diagnosis of Netherton syndrome.

Netherton syndrome is an autosomal-recessive genodermatosis characterized by a triad of congenital ichthyosis, hair shaft abnormalities, and atopic diatheses.^1,2 It affects approximately 1 in 200,000 live births^2,3; however, it is considered by many to be underdiagnosed due to the variability in the clinical appearance. Therefore, the incidence of Netherton syndrome may actually be closer 1 in 50,000 live births.¹ The manifestations of the disease are caused by a germline mutation in the SPINK5 gene, which encodes the serine protease inhibitor LEKTI.^1,2 Dysfunctional LEKTI results in increased proteolytic activity of the lipid-processing enzymes in the stratum corneum, resulting in a disruption in the lipid bilayer.¹ Dysfunctional LEKTI also results in a loss of the antiinflammatory and antimicrobial function of the stratum corneum. Clinical features of Netherton syndrome usually present at birth or shortly thereafter.¹ Congenital ichthyosiform erythroderma, or the continuous peeling of the skin, is a common presentation seen at birth and in the neonatal period.² As the patient ages, the dermatologic manifestations evolve into serpiginous and circinate, erythematous plaques with a characteristic peripheral, double-edged scaling.^1,2 This distinctive finding is termed ichthyosis linearis circumflexa and is pathognomonic for the syndrome.² Lesions often affect the trunk and extremities and demonstrate an undulating course.¹ Because eczematous and lichenified plaques in flexural areas as well as pruritus are common clinical features, this disease often is misdiagnosed as atopic dermatitis,^1,3 as was the case in our patient.

Patients with Netherton syndrome can present with various hair abnormalities. Trichorrhexis invaginata, known as bamboo hair, is the intussusception of the hair shaft and is characteristic of the disease.³ It develops from a reduced number of disulfide bonds, which results in cortical softening.¹ Trichorrhexis invaginata may not be present at birth and often improves with age.^1,3 Other hair shaft abnormalities such as pili torti, trichorrhexis nodosa, and helical hair also may be observed in Netherton syndrome.¹ Extracutaneous manifestations also are typical. There is immune dysregulation of memory B cells and natural killer cells, which manifests as frequent respiratory and skin infections as well as sepsis.^1,2 Patients also may have increased levels of serum IgE and eosinophilia resulting in atopy and allergic reactions to various triggers such as foods.¹ The neonatal period also may be complicated by dehydration, electrolyte imbalances, inability to regulate body temperature, and failure to thrive.^1,3

When there is an extensive disruption of the skin barrier during the neonatal period, there may be severe electrolyte imbalances and thermoregulatory challenges necessitating treatment in the neonatal intensive care unit. Cutaneous disease can be treated with topical therapies with variable success.¹ Topical therapies for symptom management include emollients, corticosteroids, calcineurin inhibitors, calcipotriene, and retinoids; however, utmost caution must be employed with these therapies due to the increased risk for systemic absorption resulting from the disturbance of the skin barrier. When therapy with topical tacrolimus is implemented, monitoring of serum drug levels is required.¹ Pruritus may be treated symptomatically with oral antihistamines. Intravenous immunoglobulin has been shown to decrease the frequency of infections and improve skin inflammation. Systemic retinoids have unpredictable effects and result in improvement of disease in some patients but exacerbation in others. Phototherapy with narrowband UVB, psoralen plus UVA, UVA¹, and balneophototherapy also are effective treatments for cutaneous disease.1 Dupilumab has been shown to decrease pruritus, improve hair abnormalities, and improve skin disease, thereby demonstrating its effectiveness in treating the atopy and ichthyosis in Netherton syndrome.⁴

The differential diagnosis includes other figurate erythemas including erythema marginatum and erythrokeratodermia variabilis. Erythema marginatum is a cutaneous manifestation of acute rheumatic fever and is characterized by migratory polycyclic erythematous plaques without overlying scale, usually on the trunk and proximal extremities.⁵ Erythrokeratodermia variabilis is caused by heterozygous mutations in gap junction protein beta 3, GJB3, and gap junction protein beta 4, GJB4, and is characterized by transient geographic and erythematous patches and stable scaly plaques; however, double-edged scaling is not a feature.¹ Acrodermatitis enteropathica is an autosomal-recessive disorder caused by mutations in the zinc transporter SLC39A4. Cutaneous manifestations occur after weaning from breast milk and are characterized by erythematous plaques with erosions, vesicles, and scaling, which characteristically occur in the perioral and perianal locations.6 Neonatal lupus is a form of subacute cutaneous lupus erythematosus. Typical skin lesions are erythematous annular plaques with overlying scaling, which may be present at birth and have a predilection for the face and other sun-exposed areas. Lesions generally resolve after clearance of the pathogenic maternal antibodies.⁷

The Diagnosis: Netherton Syndrome

A punch biopsy from the right lower back supported the clinical diagnosis of ichthyosis linearis circumflexa. The patient underwent genetic testing and was found to have a heterozygous mutation in the serine protease inhibitor Kazal type 5 gene, SPINK5, that was consistent with a diagnosis of Netherton syndrome.

Netherton syndrome is an autosomal-recessive genodermatosis characterized by a triad of congenital ichthyosis, hair shaft abnormalities, and atopic diatheses.^1,2 It affects approximately 1 in 200,000 live births^2,3; however, it is considered by many to be underdiagnosed due to the variability in the clinical appearance. Therefore, the incidence of Netherton syndrome may actually be closer 1 in 50,000 live births.¹ The manifestations of the disease are caused by a germline mutation in the SPINK5 gene, which encodes the serine protease inhibitor LEKTI.^1,2 Dysfunctional LEKTI results in increased proteolytic activity of the lipid-processing enzymes in the stratum corneum, resulting in a disruption in the lipid bilayer.¹ Dysfunctional LEKTI also results in a loss of the antiinflammatory and antimicrobial function of the stratum corneum. Clinical features of Netherton syndrome usually present at birth or shortly thereafter.¹ Congenital ichthyosiform erythroderma, or the continuous peeling of the skin, is a common presentation seen at birth and in the neonatal period.² As the patient ages, the dermatologic manifestations evolve into serpiginous and circinate, erythematous plaques with a characteristic peripheral, double-edged scaling.^1,2 This distinctive finding is termed ichthyosis linearis circumflexa and is pathognomonic for the syndrome.² Lesions often affect the trunk and extremities and demonstrate an undulating course.¹ Because eczematous and lichenified plaques in flexural areas as well as pruritus are common clinical features, this disease often is misdiagnosed as atopic dermatitis,^1,3 as was the case in our patient.

Patients with Netherton syndrome can present with various hair abnormalities. Trichorrhexis invaginata, known as bamboo hair, is the intussusception of the hair shaft and is characteristic of the disease.³ It develops from a reduced number of disulfide bonds, which results in cortical softening.¹ Trichorrhexis invaginata may not be present at birth and often improves with age.^1,3 Other hair shaft abnormalities such as pili torti, trichorrhexis nodosa, and helical hair also may be observed in Netherton syndrome.¹ Extracutaneous manifestations also are typical. There is immune dysregulation of memory B cells and natural killer cells, which manifests as frequent respiratory and skin infections as well as sepsis.^1,2 Patients also may have increased levels of serum IgE and eosinophilia resulting in atopy and allergic reactions to various triggers such as foods.¹ The neonatal period also may be complicated by dehydration, electrolyte imbalances, inability to regulate body temperature, and failure to thrive.^1,3

When there is an extensive disruption of the skin barrier during the neonatal period, there may be severe electrolyte imbalances and thermoregulatory challenges necessitating treatment in the neonatal intensive care unit. Cutaneous disease can be treated with topical therapies with variable success.¹ Topical therapies for symptom management include emollients, corticosteroids, calcineurin inhibitors, calcipotriene, and retinoids; however, utmost caution must be employed with these therapies due to the increased risk for systemic absorption resulting from the disturbance of the skin barrier. When therapy with topical tacrolimus is implemented, monitoring of serum drug levels is required.¹ Pruritus may be treated symptomatically with oral antihistamines. Intravenous immunoglobulin has been shown to decrease the frequency of infections and improve skin inflammation. Systemic retinoids have unpredictable effects and result in improvement of disease in some patients but exacerbation in others. Phototherapy with narrowband UVB, psoralen plus UVA, UVA¹, and balneophototherapy also are effective treatments for cutaneous disease.1 Dupilumab has been shown to decrease pruritus, improve hair abnormalities, and improve skin disease, thereby demonstrating its effectiveness in treating the atopy and ichthyosis in Netherton syndrome.⁴

The differential diagnosis includes other figurate erythemas including erythema marginatum and erythrokeratodermia variabilis. Erythema marginatum is a cutaneous manifestation of acute rheumatic fever and is characterized by migratory polycyclic erythematous plaques without overlying scale, usually on the trunk and proximal extremities.⁵ Erythrokeratodermia variabilis is caused by heterozygous mutations in gap junction protein beta 3, GJB3, and gap junction protein beta 4, GJB4, and is characterized by transient geographic and erythematous patches and stable scaly plaques; however, double-edged scaling is not a feature.¹ Acrodermatitis enteropathica is an autosomal-recessive disorder caused by mutations in the zinc transporter SLC39A4. Cutaneous manifestations occur after weaning from breast milk and are characterized by erythematous plaques with erosions, vesicles, and scaling, which characteristically occur in the perioral and perianal locations.6 Neonatal lupus is a form of subacute cutaneous lupus erythematosus. Typical skin lesions are erythematous annular plaques with overlying scaling, which may be present at birth and have a predilection for the face and other sun-exposed areas. Lesions generally resolve after clearance of the pathogenic maternal antibodies.⁷

THE PRESENTATION

Severe long-standing hidradenitis suppurativa (Hurley stage III) with architectural changes, ropy scarring, granulation tissue, and purulent discharge in the axilla of a 35-year-old Black man (A) and a 42-year-old Hispanic woman with a light skin tone (B).

Photographs courtesy of Richard P. Usatine, MD.

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the follicular epithelium that most commonly is found in the axillae and buttocks, as well as the inguinal, perianal, and submammary areas. It is characterized by firm and tender chronic nodules, abscesses complicated by sinus tracts, fistulae, and scarring thought to be related to follicular occlusion. Double-open comedones also may be seen.

The Hurley staging system is widely used to characterize the extent of disease in HS patients:

• Stage I (mild): nodule(s) and abscess(es) without sinus tracts (tunnels) or scarring;
• Stage II (moderate): recurrent nodule(s) and abscess(es) with a limited number of sinus tracts (tunnels) and/or scarring; and
• Stage III (severe): multiple or extensive sinus tracts (tunnels), abscesses, and/or scarring across the entire area.

Epidemiology

Hidradenitis suppurativa is most common in adults and African American patients. It has a prevalence of 1.3% in African Americans.¹ When it occurs in children, it generally develops after the onset of puberty. The incidence is higher in females as well as individuals with a history of smoking and obesity (a higher body mass index).^2-5

Key clinical features in people with darker skin tones

The erythema associated with HS may be difficult to see in darker skin tones, but violaceous, dark brown, and gray lesions may be present. When active HS lesions subside, intense hyperpigmentation may be left behind, and in some skin tones a pink or violaceous lesion may be apparent.

Worth noting

Hidradenitis suppurativa is disfiguring and has a negative impact on quality of life, including social relationships. Mental health support and screening tools are useful. Pain also is a common concern and may warrant referral to a pain specialist.⁶ In early disease, HS lesions can be misdiagnosed as an infection that recurs in the same location.

Treatments for HS include oral antibiotics (ie, tetracyclines, rifampin, clindamycin), topical antibiotics, immunosuppressing biologics, metformin, and spironolactone.⁷ Surgical interventions may be considered earlier in HS management and vary based on the location and severity of the lesions.⁸

Patients with HS are at risk for developing squamous cell carcinoma in scars even many years later⁹; therefore, patients should perform skin checks and be referred to a dermatologist. Squamous cell carcinoma is most commonly found on the buttocks of men with HS and has a poor prognosis.

Health disparity highlight

Although those of African American and African descent have the highest rates of HS,¹ the clinical trials for adalimumab (the only biologic approved for HS) enrolled a low number of Black patients.

Thirty HS comorbidities have been identified. Garg et al¹⁰ recommended that dermatologists perform examinations for comorbid conditions involving the skin and conduct a simple review of systems for extracutaneous comorbidities. Access to medical care is essential, and health care system barriers affect the ability of some patients to receive adequate continuity of care.

The diagnosis of HS often is delayed due to lack of HS knowledge about the condition in the medical community at large and delayed presentation to a dermatologist.

THE PRESENTATION

Severe long-standing hidradenitis suppurativa (Hurley stage III) with architectural changes, ropy scarring, granulation tissue, and purulent discharge in the axilla of a 35-year-old Black man (A) and a 42-year-old Hispanic woman with a light skin tone (B).

Photographs courtesy of Richard P. Usatine, MD.

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the follicular epithelium that most commonly is found in the axillae and buttocks, as well as the inguinal, perianal, and submammary areas. It is characterized by firm and tender chronic nodules, abscesses complicated by sinus tracts, fistulae, and scarring thought to be related to follicular occlusion. Double-open comedones also may be seen.

The Hurley staging system is widely used to characterize the extent of disease in HS patients:

• Stage I (mild): nodule(s) and abscess(es) without sinus tracts (tunnels) or scarring;
• Stage II (moderate): recurrent nodule(s) and abscess(es) with a limited number of sinus tracts (tunnels) and/or scarring; and
• Stage III (severe): multiple or extensive sinus tracts (tunnels), abscesses, and/or scarring across the entire area.

Epidemiology

Hidradenitis suppurativa is most common in adults and African American patients. It has a prevalence of 1.3% in African Americans.¹ When it occurs in children, it generally develops after the onset of puberty. The incidence is higher in females as well as individuals with a history of smoking and obesity (a higher body mass index).^2-5

Key clinical features in people with darker skin tones

The erythema associated with HS may be difficult to see in darker skin tones, but violaceous, dark brown, and gray lesions may be present. When active HS lesions subside, intense hyperpigmentation may be left behind, and in some skin tones a pink or violaceous lesion may be apparent.

Worth noting

Hidradenitis suppurativa is disfiguring and has a negative impact on quality of life, including social relationships. Mental health support and screening tools are useful. Pain also is a common concern and may warrant referral to a pain specialist.⁶ In early disease, HS lesions can be misdiagnosed as an infection that recurs in the same location.

Treatments for HS include oral antibiotics (ie, tetracyclines, rifampin, clindamycin), topical antibiotics, immunosuppressing biologics, metformin, and spironolactone.⁷ Surgical interventions may be considered earlier in HS management and vary based on the location and severity of the lesions.⁸

Patients with HS are at risk for developing squamous cell carcinoma in scars even many years later⁹; therefore, patients should perform skin checks and be referred to a dermatologist. Squamous cell carcinoma is most commonly found on the buttocks of men with HS and has a poor prognosis.

Health disparity highlight

Although those of African American and African descent have the highest rates of HS,¹ the clinical trials for adalimumab (the only biologic approved for HS) enrolled a low number of Black patients.

Thirty HS comorbidities have been identified. Garg et al¹⁰ recommended that dermatologists perform examinations for comorbid conditions involving the skin and conduct a simple review of systems for extracutaneous comorbidities. Access to medical care is essential, and health care system barriers affect the ability of some patients to receive adequate continuity of care.

The diagnosis of HS often is delayed due to lack of HS knowledge about the condition in the medical community at large and delayed presentation to a dermatologist.

THE PRESENTATION

Severe long-standing hidradenitis suppurativa (Hurley stage III) with architectural changes, ropy scarring, granulation tissue, and purulent discharge in the axilla of a 35-year-old Black man (A) and a 42-year-old Hispanic woman with a light skin tone (B).

Photographs courtesy of Richard P. Usatine, MD.

Hidradenitis suppurativa (HS) is a chronic inflammatory condition of the follicular epithelium that most commonly is found in the axillae and buttocks, as well as the inguinal, perianal, and submammary areas. It is characterized by firm and tender chronic nodules, abscesses complicated by sinus tracts, fistulae, and scarring thought to be related to follicular occlusion. Double-open comedones also may be seen.

The Hurley staging system is widely used to characterize the extent of disease in HS patients:

• Stage I (mild): nodule(s) and abscess(es) without sinus tracts (tunnels) or scarring;
• Stage II (moderate): recurrent nodule(s) and abscess(es) with a limited number of sinus tracts (tunnels) and/or scarring; and
• Stage III (severe): multiple or extensive sinus tracts (tunnels), abscesses, and/or scarring across the entire area.

Epidemiology

Hidradenitis suppurativa is most common in adults and African American patients. It has a prevalence of 1.3% in African Americans.¹ When it occurs in children, it generally develops after the onset of puberty. The incidence is higher in females as well as individuals with a history of smoking and obesity (a higher body mass index).^2-5

Key clinical features in people with darker skin tones

The erythema associated with HS may be difficult to see in darker skin tones, but violaceous, dark brown, and gray lesions may be present. When active HS lesions subside, intense hyperpigmentation may be left behind, and in some skin tones a pink or violaceous lesion may be apparent.

Worth noting

Hidradenitis suppurativa is disfiguring and has a negative impact on quality of life, including social relationships. Mental health support and screening tools are useful. Pain also is a common concern and may warrant referral to a pain specialist.⁶ In early disease, HS lesions can be misdiagnosed as an infection that recurs in the same location.

Treatments for HS include oral antibiotics (ie, tetracyclines, rifampin, clindamycin), topical antibiotics, immunosuppressing biologics, metformin, and spironolactone.⁷ Surgical interventions may be considered earlier in HS management and vary based on the location and severity of the lesions.⁸

Patients with HS are at risk for developing squamous cell carcinoma in scars even many years later⁹; therefore, patients should perform skin checks and be referred to a dermatologist. Squamous cell carcinoma is most commonly found on the buttocks of men with HS and has a poor prognosis.

Health disparity highlight

Although those of African American and African descent have the highest rates of HS,¹ the clinical trials for adalimumab (the only biologic approved for HS) enrolled a low number of Black patients.

Thirty HS comorbidities have been identified. Garg et al¹⁰ recommended that dermatologists perform examinations for comorbid conditions involving the skin and conduct a simple review of systems for extracutaneous comorbidities. Access to medical care is essential, and health care system barriers affect the ability of some patients to receive adequate continuity of care.

The diagnosis of HS often is delayed due to lack of HS knowledge about the condition in the medical community at large and delayed presentation to a dermatologist.

The Diagnosis: Cutaneous Lymphoid Hyperplasia

Cutaneous lymphoid hyperplasia (CLH)(also known as pseudolymphoma or lymphocytoma cutis) is a benign inflammatory condition that typically presents as a flesh-colored to erythematous or violaceous papule or nodule on the head or neck. Cutaneous lymphoid hyperplasia may arise in response to an antigenic stimulus, such as an insect bite, infectious agent (eg, Borrelia species), medication, or foreign body (eg, tattoos and piercings).^1,2 Given the benign nature and potential for spontaneous resolution, treatment is conservative; however, high-potency topical steroids, cryosurgery, surgical excision, or local radiotherapy may lead to improvement.³ Our patient was started on clobetasol ointment 0.05% and topical tacrolimus 0.1%. After 3 months of use, she reported lesion improvement, but a new lesion appeared on the nose superior to the original. She was offered a steroid injection and liquid nitrogen freezing but was lost to follow-up.

The histopathologic features of CLH are variable and can resemble a cutaneous B- or T-cell lymphoma (quiz images). If there is B-cell predominance, histopathology typically shows a dense dermal infiltrate of lymphocytes admixed with sparse histiocytes, eosinophils, and plasma cells. Multiple germinal-center phenotype lymphoid follicles also may be seen.⁴ Histopathology of T-cell–predominant CLH commonly shows CD4⁺ T helper lymphocytes admixed with CD8⁺ T cells within the dermis with possible papillary dermal edema and red cell extravasation.⁵ Immunohistochemical stains for CD3, CD4, CD8, and CD20 usually are positive. Most lymphocytes are CD3⁺ T cells. Admixed clusters of CD20⁺ B cells may be present.

Angiolymphoid hyperplasia with eosinophilia is a vascular tumor of the skin composed of endothelial cells and inflammatory cells.^6,7 The condition presents as single or multiple flesh-colored to purple papules most commonly on the face, scalp, and ears.⁸ Histologically, lesions appear as well-circumscribed collections of blood vessels composed of plump endothelial cells and an inflammatory infiltrate with lymphocytes and eosinophils (Figure 1A). Endothelial cells also may have an epithelioid appearance.⁷ Apparent fenestrations—holes within endothelial cells—may be present (Figure 1B). Surgical excision is the preferred treatment of angiolymphoid hyperplasia with eosinophilia. Success with laser and cryosurgery also has been reported.

Granuloma faciale typically presents as a solitary redbrown papule or plaque on the face. Linear arborizing vessels and dilated follicular openings with brown globules frequently are seen on dermoscopy.⁹ Although it may resemble CLH clinically, the histopathology of granuloma faciale is characterized by a perivascular and interstitial dermal infiltrate of numerous eosinophils admixed with lymphocytes, plasma cells, and neutrophils underneath a grenz zone (Figure 2).¹⁰ Leukocytoclastic vasculitis may be seen in early lesions, and lesions can show variable angiocentric fibrosis.¹¹ Treatment options include intralesional triamcinolone, topical steroids or calcineurin inhibitors, topical psoralen plus UVA, surgical excision, and laser therapy, but outcomes are variable.¹²

Leukemia cutis is a malignant hematopoietic skin infiltration that presents as multiple pink to red-brown, firm, hemorrhagic papules most frequently involving the head, neck, and trunk.¹³ Rarely, lesions of leukemia cutis may present as ulcers or bullae. Most lesions occur at presentation of systemic leukemia or in the setting of established leukemia. The cutaneous involvement portends a poor prognosis, strongly correlating with additional extramedullary leukemic involvement.¹⁴ Histologic features vary based on the specific type of leukemia (eg, acute myelogenous leukemia). Generally, neoplastic infiltration of the dermis and subcutaneous tissue in a nodular, diffuse, perivascular, or interstitial pattern is seen (Figure 3).¹⁵ Leukemia cutis typically resolves after successful treatment of the underlying leukemia.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. In its early stages, MF presents as erythematous, brown, scaly patches and plaques. With progression to the tumor stage of disease, clonal expansion of CD4⁺ T cells leads to the development of purple papules and nodules.¹⁶ Microscopic findings of MF are dependent on the stage of disease. Early patch lesions show superficial or lichenoid lymphocytic infiltration of the epidermal basal layer.¹⁷ In the plaque stage, dermal infiltrates and epidermotropism become more pronounced, with increased atypical lymphocytes with cerebriform nuclei and interspersed inflammatory cells (Figure 4). In the tumor stage, lymphocytic infiltrates may involve the entirety of the dermis or extend into the subcutaneous tissue, and malignant cells become larger in size.¹⁷ Mycosis fungoides lesions typically stain positive for helper T-cell markers with a minority staining positive for CD8.

The Diagnosis: Cutaneous Lymphoid Hyperplasia

Cutaneous lymphoid hyperplasia (CLH)(also known as pseudolymphoma or lymphocytoma cutis) is a benign inflammatory condition that typically presents as a flesh-colored to erythematous or violaceous papule or nodule on the head or neck. Cutaneous lymphoid hyperplasia may arise in response to an antigenic stimulus, such as an insect bite, infectious agent (eg, Borrelia species), medication, or foreign body (eg, tattoos and piercings).^1,2 Given the benign nature and potential for spontaneous resolution, treatment is conservative; however, high-potency topical steroids, cryosurgery, surgical excision, or local radiotherapy may lead to improvement.³ Our patient was started on clobetasol ointment 0.05% and topical tacrolimus 0.1%. After 3 months of use, she reported lesion improvement, but a new lesion appeared on the nose superior to the original. She was offered a steroid injection and liquid nitrogen freezing but was lost to follow-up.

The histopathologic features of CLH are variable and can resemble a cutaneous B- or T-cell lymphoma (quiz images). If there is B-cell predominance, histopathology typically shows a dense dermal infiltrate of lymphocytes admixed with sparse histiocytes, eosinophils, and plasma cells. Multiple germinal-center phenotype lymphoid follicles also may be seen.⁴ Histopathology of T-cell–predominant CLH commonly shows CD4⁺ T helper lymphocytes admixed with CD8⁺ T cells within the dermis with possible papillary dermal edema and red cell extravasation.⁵ Immunohistochemical stains for CD3, CD4, CD8, and CD20 usually are positive. Most lymphocytes are CD3⁺ T cells. Admixed clusters of CD20⁺ B cells may be present.

Angiolymphoid hyperplasia with eosinophilia is a vascular tumor of the skin composed of endothelial cells and inflammatory cells.^6,7 The condition presents as single or multiple flesh-colored to purple papules most commonly on the face, scalp, and ears.⁸ Histologically, lesions appear as well-circumscribed collections of blood vessels composed of plump endothelial cells and an inflammatory infiltrate with lymphocytes and eosinophils (Figure 1A). Endothelial cells also may have an epithelioid appearance.⁷ Apparent fenestrations—holes within endothelial cells—may be present (Figure 1B). Surgical excision is the preferred treatment of angiolymphoid hyperplasia with eosinophilia. Success with laser and cryosurgery also has been reported.

Granuloma faciale typically presents as a solitary redbrown papule or plaque on the face. Linear arborizing vessels and dilated follicular openings with brown globules frequently are seen on dermoscopy.⁹ Although it may resemble CLH clinically, the histopathology of granuloma faciale is characterized by a perivascular and interstitial dermal infiltrate of numerous eosinophils admixed with lymphocytes, plasma cells, and neutrophils underneath a grenz zone (Figure 2).¹⁰ Leukocytoclastic vasculitis may be seen in early lesions, and lesions can show variable angiocentric fibrosis.¹¹ Treatment options include intralesional triamcinolone, topical steroids or calcineurin inhibitors, topical psoralen plus UVA, surgical excision, and laser therapy, but outcomes are variable.¹²

Leukemia cutis is a malignant hematopoietic skin infiltration that presents as multiple pink to red-brown, firm, hemorrhagic papules most frequently involving the head, neck, and trunk.¹³ Rarely, lesions of leukemia cutis may present as ulcers or bullae. Most lesions occur at presentation of systemic leukemia or in the setting of established leukemia. The cutaneous involvement portends a poor prognosis, strongly correlating with additional extramedullary leukemic involvement.¹⁴ Histologic features vary based on the specific type of leukemia (eg, acute myelogenous leukemia). Generally, neoplastic infiltration of the dermis and subcutaneous tissue in a nodular, diffuse, perivascular, or interstitial pattern is seen (Figure 3).¹⁵ Leukemia cutis typically resolves after successful treatment of the underlying leukemia.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. In its early stages, MF presents as erythematous, brown, scaly patches and plaques. With progression to the tumor stage of disease, clonal expansion of CD4⁺ T cells leads to the development of purple papules and nodules.¹⁶ Microscopic findings of MF are dependent on the stage of disease. Early patch lesions show superficial or lichenoid lymphocytic infiltration of the epidermal basal layer.¹⁷ In the plaque stage, dermal infiltrates and epidermotropism become more pronounced, with increased atypical lymphocytes with cerebriform nuclei and interspersed inflammatory cells (Figure 4). In the tumor stage, lymphocytic infiltrates may involve the entirety of the dermis or extend into the subcutaneous tissue, and malignant cells become larger in size.¹⁷ Mycosis fungoides lesions typically stain positive for helper T-cell markers with a minority staining positive for CD8.

The Diagnosis: Cutaneous Lymphoid Hyperplasia

Cutaneous lymphoid hyperplasia (CLH)(also known as pseudolymphoma or lymphocytoma cutis) is a benign inflammatory condition that typically presents as a flesh-colored to erythematous or violaceous papule or nodule on the head or neck. Cutaneous lymphoid hyperplasia may arise in response to an antigenic stimulus, such as an insect bite, infectious agent (eg, Borrelia species), medication, or foreign body (eg, tattoos and piercings).^1,2 Given the benign nature and potential for spontaneous resolution, treatment is conservative; however, high-potency topical steroids, cryosurgery, surgical excision, or local radiotherapy may lead to improvement.³ Our patient was started on clobetasol ointment 0.05% and topical tacrolimus 0.1%. After 3 months of use, she reported lesion improvement, but a new lesion appeared on the nose superior to the original. She was offered a steroid injection and liquid nitrogen freezing but was lost to follow-up.

The histopathologic features of CLH are variable and can resemble a cutaneous B- or T-cell lymphoma (quiz images). If there is B-cell predominance, histopathology typically shows a dense dermal infiltrate of lymphocytes admixed with sparse histiocytes, eosinophils, and plasma cells. Multiple germinal-center phenotype lymphoid follicles also may be seen.⁴ Histopathology of T-cell–predominant CLH commonly shows CD4⁺ T helper lymphocytes admixed with CD8⁺ T cells within the dermis with possible papillary dermal edema and red cell extravasation.⁵ Immunohistochemical stains for CD3, CD4, CD8, and CD20 usually are positive. Most lymphocytes are CD3⁺ T cells. Admixed clusters of CD20⁺ B cells may be present.

Angiolymphoid hyperplasia with eosinophilia is a vascular tumor of the skin composed of endothelial cells and inflammatory cells.^6,7 The condition presents as single or multiple flesh-colored to purple papules most commonly on the face, scalp, and ears.⁸ Histologically, lesions appear as well-circumscribed collections of blood vessels composed of plump endothelial cells and an inflammatory infiltrate with lymphocytes and eosinophils (Figure 1A). Endothelial cells also may have an epithelioid appearance.⁷ Apparent fenestrations—holes within endothelial cells—may be present (Figure 1B). Surgical excision is the preferred treatment of angiolymphoid hyperplasia with eosinophilia. Success with laser and cryosurgery also has been reported.

Granuloma faciale typically presents as a solitary redbrown papule or plaque on the face. Linear arborizing vessels and dilated follicular openings with brown globules frequently are seen on dermoscopy.⁹ Although it may resemble CLH clinically, the histopathology of granuloma faciale is characterized by a perivascular and interstitial dermal infiltrate of numerous eosinophils admixed with lymphocytes, plasma cells, and neutrophils underneath a grenz zone (Figure 2).¹⁰ Leukocytoclastic vasculitis may be seen in early lesions, and lesions can show variable angiocentric fibrosis.¹¹ Treatment options include intralesional triamcinolone, topical steroids or calcineurin inhibitors, topical psoralen plus UVA, surgical excision, and laser therapy, but outcomes are variable.¹²

Leukemia cutis is a malignant hematopoietic skin infiltration that presents as multiple pink to red-brown, firm, hemorrhagic papules most frequently involving the head, neck, and trunk.¹³ Rarely, lesions of leukemia cutis may present as ulcers or bullae. Most lesions occur at presentation of systemic leukemia or in the setting of established leukemia. The cutaneous involvement portends a poor prognosis, strongly correlating with additional extramedullary leukemic involvement.¹⁴ Histologic features vary based on the specific type of leukemia (eg, acute myelogenous leukemia). Generally, neoplastic infiltration of the dermis and subcutaneous tissue in a nodular, diffuse, perivascular, or interstitial pattern is seen (Figure 3).¹⁵ Leukemia cutis typically resolves after successful treatment of the underlying leukemia.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. In its early stages, MF presents as erythematous, brown, scaly patches and plaques. With progression to the tumor stage of disease, clonal expansion of CD4⁺ T cells leads to the development of purple papules and nodules.¹⁶ Microscopic findings of MF are dependent on the stage of disease. Early patch lesions show superficial or lichenoid lymphocytic infiltration of the epidermal basal layer.¹⁷ In the plaque stage, dermal infiltrates and epidermotropism become more pronounced, with increased atypical lymphocytes with cerebriform nuclei and interspersed inflammatory cells (Figure 4). In the tumor stage, lymphocytic infiltrates may involve the entirety of the dermis or extend into the subcutaneous tissue, and malignant cells become larger in size.¹⁷ Mycosis fungoides lesions typically stain positive for helper T-cell markers with a minority staining positive for CD8.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are 2 common inflammatory skin conditions that may have similar clinical presentations. Historically, it was thought that these conditions could not be diagnosed simultaneously due to their differing immune mechanisms; however, this belief has been challenged by recent evidence suggesting a more nuanced relationship between the 2 disease processes. In this review, we examine the complex interplay between AD and ACD and explain how shifts in conventional understanding of the 2 conditions shaped our evolving recognition of their ability to coexist.

Epidemiology of AD and ACD

Atopic dermatitis is the most common inflammatory skin disease in children and adolescents, with an estimated prevalence reaching 21%.¹ In 60% of cases, onset of AD will occur within the first year of life, and 90% of cases begin within the first 5 years.² Resolution may occur by adulthood; however, AD may continue to impact up to 8% to 9% of adults, with an increased prevalence in those older than 75 years.¹ This may represent an underestimation of the burden of adult AD; one systematic review of 17 studies found that the pooled proportion of adult-onset AD was greater than 25%.³

In contrast, ACD previously was assumed to be a disease that more commonly impacted adults and only rarely children, primarily due to an early misconception that children were not frequently exposed to contact allergens and their immune systems were too immature to react to them even if exposed.^4,5 However, it is now known that children do have risk factors for development of ACD, including a thinner stratum corneum and potentially a more absorbent skin surface.⁴ In addition, a 2022 study by the North American Contact Dermatitis Group (NACDG) found similar rates of ACD in children (n=1871) and adults (n=41,699) referred for patch testing (55.2% and 57.3%, respectively) as well as similar rates of having at least 1 relevant positive patch test (49.2% and 52.2%).⁶

In opposition to traditional beliefs, these findings highlight that AD and ACD can occur across age groups.

Immune Mechanism

The pathogenesis of AD represents a multifactorial process involving the immune system, cutaneous flora, genetic predisposition, and surrounding environment. Immunologically, acute AD is driven by a predominantly T_H2 helper T-cell response with high levels of IL-4, IL-5, and IL-13⁷; T_H22, T_H17, and T_H1 also have been implicated.⁸ Notably, T_H17 is found in high levels during the acute eczema phase, while T_H1 and T_H22are associated with the chronic phase.⁷

The pathophysiology of ACD is not completely understood. The classic paradigm involves 2 phases: sensitization and elicitation. Sensitization involves antigen-presenting cells that take up allergens absorbed by the skin to present them in regional lymph nodes where antigen-specific T lymphocytes are generated. Elicitation occurs upon re-exposure to the allergen, at which time the primed T lymphocytes are recruited to the skin, causing inflammation.⁹ Allergic contact dermatitis initially was thought to be driven by T_H1 cytokines and IL-17 but now is understood to be more complex.¹⁰ Studies have revealed immune polarization of contact allergens, demonstrating that nickel primarily induces a T_H1/T_H17 response, whereas fragrance and rubber accelerators skew to T_H2; T_H9 and T_H22 also may be involved depending on the causative allergen.^11,12

Of note, the immunologic differences between AD and ACD led early investigators to believe that patients with AD were relatively protected from ACD.¹³ However, as previously described, there are several overlapping cytokines between AD and ACD. Furthermore, research has revealed that risk of contact sensitization might be increased in the chronic eczema phase due to the shared T_H1 pathway.¹⁴ Barrier-disrupted skin (such as that in AD) also may increase the cytokine response and the density of antigen-presenting cells, leading to a proallergic state.¹⁵ This suggests that the immunologic pathways of AD and ACD are more intertwined than was previously understood.

Underlying Risk Factors

Skin barrier dysfunction is a key step in the pathogenesis of AD. Patients with AD commonly have loss-of-function mutations in the filaggrin gene, a protein that is key to the function of the stratum corneum. Loss of this protein may not only impact the immune response as previously noted but also may lead to increased transepidermal water loss and bacterial colonization.¹⁶ Interestingly, a 2014 review examined how this mutation could lead to an increased risk of sensitization to bivalent metal ions via an impaired chelating ability of the skin.¹⁷ Furthermore, a 2016 study conducted in Dutch construction workers revealed an increased risk for contact dermatitis (irritant and allergic) for those with a loss-of-function filaggrin mutation.¹⁸

Importantly, this same mutation may explain why patients with AD tend to have increased skin colonization by Staphylococcus aureus. The abundance of S aureus and the relative decrease in the diversity of other microorganisms on the skin may be associated with increased AD severity.¹⁹ Likewise, S aureus may play a role in the pathogenesis of ACD via production of its exotoxin directed at the T-cell receptor V beta 17 region. In particular, this receptor has been associated with nickel sensitization.¹⁷

Another risk factor to consider is increased exposure to contact sensitizers when treating AD. For instance, management often includes use of over-the-counter emollients, natural or botanical remedies with purported benefits for AD, cleansers, and detergents. However, these products can contain some of the most prevalent contact allergens seen in those with AD, including methyl-isothiazolinone, formaldehyde releasers, and fragrance.²⁰ Topical corticosteroids also are frequently used, and ACD to steroid molecules can occur, particularly to tixocortol-21-pivalate (a marker for class A corticosteroids) and budesonide (a marker for class B corticosteroids).²¹ Other allergens (eg, benzyl alcohol, propylene glycol) also may be found as inactive ingredients of topical corticosteroids.²² These exposures may place AD patients at risk for ACD.

The Coexistence of AD and ACD

Given the overlapping epidemiology, immunology, and potentially increased risk for the development of ACD in patients with AD, it would be reasonable to assume that the 2 diagnoses could coexist; however, is there clinical data to support this idea? Based on recent database reviews, the answer appears to be yes.^20,23-26 An analysis from the Pediatric Contact Dermatitis Registry revealed that 30% of 1142 pediatric patch test cases analyzed were diagnosed as AD and ACD simultaneously.²⁴ The NACDG found similar results in its 2021 review, as 29.5% of children (n=1648) and 20.7% of adults (n=36,834) had a concurrent diagnosis of AD and ACD.²⁰ Notably, older results from these databases also demonstrated an association between the 2 conditions.^23,25,26

It remains unclear whether the prevalence of ACD is higher in those with or without AD. A comprehensive systematic review conducted in 2017 examined this topic through analysis of 74 studies. The results demonstrated a similar prevalence of contact sensitization in individuals with and without AD.²⁷ Another systematic review of 31 studies conducted in 2017 found a higher prevalence for ACD in children without AD; however, the authors noted that the included studies were too variable (eg, size, design, allergens tested) to draw definitive conclusions.²⁸

Even though there is no clear overall increased risk for ACD in patients with AD, research has suggested that certain allergens may be more prevalent in the setting of AD. An NACDG study found that adults with AD had increased odds of reacting to 10 of the top 25 NACDG screening allergens compared to those without AD.²⁰ Other studies have found that AD patients may be more likely to become sensitized to certain allergens, such as fragrance and lanolin.¹⁴

Considerations for Management

Diagnosis of ACD in patients with AD can be challenging because these conditions may present similarly with chronic, pruritic, inflammatory patches and plaques. Chronic ACD may be misdiagnosed as AD if patch testing is not performed.²⁹ Given the prevalence of ACD in the setting of AD, there should be a low threshold to pursue patch testing, especially when dermatitis is recalcitrant to standard therapies or presents in an atypical distribution (ie, perioral, predominantly head/neck, hand and foot, isolated eyelid involvement, buttocks).^4,30 Various allergen series are available for patch testing adults and children including the NACDG Standard Series, American Contact Dermatitis Society Core Allergen Series, or the Pediatric Baseline Series.^31-33

If potentially relevant allergens are uncovered by patch testing, patients should be counseled on avoidance strategies. However, allergen avoidance may not always lead to complete symptom resolution, especially if AD is present concomitantly with ACD. Therefore, use of topical or systemic therapies still may be required. Topical corticosteroids can be used when dermatitis is acute and localized. Systemic corticosteroids are utilized for both diagnoses when cases are more severe or extensive, but their adverse-effect profile limits long-term use. Other systemic treatments, including conventional agents (ie, azathioprine, cyclosporine, methotrexate, mycophenolate mofetil), biologics, and small molecule inhibitors also may be considered for severe cases.^34,35 Dupilumab, a monoclonal antibody targeting IL-4/IL-13, is approved for use in moderate to severe AD in patients 6 months and older. Recent evidence has suggested that dupilumab also may be an effective off-label treatment choice for ACD when allergen avoidance alone is insufficient.³⁶ Studies have been conducted on secukinumab, a monoclonal antibody against IL-17; however, it has not been shown to be effective in either AD or ACD.^37,38 This indicates that targeted biologics may not always be successful in treating these diagnoses, likely due to their complex immune pathways. Finally, there is an emerging role for JAK inhibitors. Three are approved for AD: topical ruxolitinib, oral abrocitinib, and oral upadacitinib.³⁹ Further investigation is needed to determine the efficacy of JAK inhibitors in ACD.

Final Interpretation

Evolving evidence shows that AD and ACD can occur at the same time despite the historical perspective that their immune pathways were too polarized for this to happen. Atopic dermatitis may be an important risk factor for subsequent development of ACD. Management should include a low threshold to perform patch testing, while pharmacotherapies utilized in the treatment of both conditions should be considered.

Basal cell carcinomas (BCCs) are considered the most common cutaneous cancers. Approximately 80% of nonmelanoma skin cancers are BCCs.^1,2 Surgical management is the gold standard for early-stage and localized BCCs; it may include simple excision vs Mohs micrographic surgery.^3,4 However, if left untreated, these lesions can progress to an advanced stage (locally advanced BCC) or infrequently may spread to distant sites (metastatic BCC). In the advanced stage, the lesions are no longer manageable by surgery or radiation therapy.^5,6 Recently, inhibitors targeting the hedgehog (Hh) pathway have shown great promise for these patients. The first drug approved by the US Food and Drug Administration (FDA) for locally advanced and metastatic BCC is vismodegib.⁷ In this article, we provide a clinical review of vismodegib for the management of BCC, including a discussion of the Hh pathway in BCC, adverse effects of vismodegib, use of vismodegib in adnexal skin tumors, recommended doses for vismodegib therapy in BCC, and management of the side effects of treatment.

Hh Pathway in BCC

In embryonic development, the Hh signaling pathway is crucial across a broad spectrum of species, including humans. Various members of the Hh family have been recognized, all working as secreted regulatory proteins.⁸ The name of the Hh signaling pathway is derived from a polypeptide ligand called hedgehog found in some fruit flies. Mutations in the gene led to fruit fly larvae that had a spiky hairy pattern of denticles similar to hedgehogs, leading to the name of this molecule.⁹ The transmembrane protein smoothened (SMO) is the main component of the Hh signaling pathway and initiates a signaling cascade that in turn leads to an increased expression of target genes, such as GLI1. Patched (PTCH), also a transmembrane protein and a cell-surface receptor for the secreted Hh ligand, suppresses the signaling capacity of SMO. Upon binding of the Hh ligand to the PTCH receptor, the suppression of SMO is relieved and a signal is propagated, evoking a cellular response.¹⁰ Molecular and genetic studies have reported that genetic alterations in the Hh signaling pathway are almost universally present in all BCCs, leading to an aberrant activation of the pathway and an uncontrolled proliferation of the basal cells. Frequently, these alterations have been shown to cause loss of function of PTCH homologue 1, which usually acts to inhibit the SMO homologue signaling activity.^11,12

Because of the potential importance of Hh signaling in other solid malignancies and the failure of topical inhibition of SMO,¹³ subsequent studies on the development of Hh pathway inhibitors have mostly focused on the systemic approach. A multitude of Hh pathway inhibitors have been developed thus far, such as SANT1-SANT4, GDC-0449, IPI-926, BMS-833923 (XL139), HhAntag-691, and MK-4101.¹⁴ Many of these inhibitors have been clinically investigated.^13,15,16

Systemic SMO Inhibitor: Vismodegib

Vismodegib was the earliest systemic SMO inhibitor to fulfill early clinical evaluation^15,16 and the first drug to receive FDA approval for the management of advanced or metastatic BCC. Vismodegib is a small-molecule SMO inhibitor used for the management of selected locally advanced BCC and metastatic BCC in adults.^3,17 Although there is a possibility of recurrence following drug withdrawal, vismodegib constitutes a new therapeutic strategy presenting positive benefits to patients. It may provide superior improvement over sunitinib, which has shown efficacy in a few patients; however, the efficacy and tolerance of sunitinib have been shown to be limited.^18,19

Adverse Effects of Vismodegib Therapy

Adverse events with vismodegib use have been reported in 98% of patients (N=491); most of these were mild to moderate.²⁰ However, the frequency of adverse events could prove to be a therapeutic challenge for patients requiring extended treatment. The most frequently reported reversible side effects were muscle spasms (64%), alopecia (62%), weight loss (33%), fatigue (28%), decreased appetite (25%), diarrhea (17%), nausea (16%), dysgeusia (54%), and ageusia (22%).²⁰ In clinical trials, amenorrhea was noticed in 30% (3/10) of females with reproductive potential.² Apart from alopecia and possibly amenorrhea, these side effects are reversible.¹⁷ Alkeraye et al¹⁷ reported 3 clinical cases of persistent alopecia following the use of vismodegib. Amenorrhea is a possible side effect of unknown reversibility.⁷

Vismodegib is a pregnancy category D medication.⁴ Severe birth defects, including craniofacial abnormalities, retardations in normal growth, open perineum, and absence of digital fusion at a corresponding 20% of the recommended daily dose, were found in rat studies. Embryo-fetal death was noted when rats were exposedto concentrations comparable to the recommended human dose.⁴

Hepatic events with the use of vismodegib have been reported. The use of vismodegib in randomized controlled trials resulted in elevation of both alanine aminotransferase and aspartate aminotransferase levels compared with placebo.²¹ Moreover, severe hepatotoxicity with vismodegib has been reported.^22-24 A study conducted by Edwards et al²⁵ concluded that the use of vismodegib in patients with severe liver disease must include thorough risk-benefit assessment, with caution in using other concomitant hepatotoxic medications.

Rare adverse events also have been reported in the literature, including vismodegib-induced pancreatitis in a 79-year-old patient treated for locally advanced, recurrent BCC that was cleared following cessation of therapy.²⁶ Additionally, atypical fibroxanthoma was observed in an 83-year-old patient after 30 days of treatment with vismodegib for multiple BCCs.²⁷ The development of other secondary malignancies, such as squamous cell carcinoma, melanoma, keratoacanthomas, and pilomatricomas, during or after the long-term use of vismodegib also have been described.^28-35

Use of Vismodegib for Adnexal Skin Tumors

The role of the sonic Hh–PTCH pathway in the pathogenesis of adnexal tumors varies in the literature. Some studies propose the involvement of this pathway in the formation of adnexal tumors such as trichoblastoma, trichoepithelioma, and cylindroma, as in BCC. Various lines of evidence support this involvement. Firstly, in mice, the spontaneous generation of numerous BCCs, trichoblastomas, trichoepitheliomas, and cylindromas has been observed following constitutive activation of the sonic Hh–PTCH pathway.³⁶ Secondly, in trichoepitheliomas, there have been positive results in molecular research into the tumor suppressor gene PTCH homologue 1, PTCH1, whose mutations cause constitutive activation of the sonic Hh–PTCH pathway.³⁷ Thirdly, GLI1³⁸ and SOX9³⁹ transcription factors associated with the signaling pathway of sonic Hh–PTCH appear to have increased levels in adnexal carcinomas.¹⁹ Lepesant et al¹⁹ reported a notable clinical response to vismodegib in trichoblastic carcinoma. Baur et al⁴⁰ reported successful treatment of multiple familial trichoepitheliomas with vismodegib. Nonetheless, more studies are required to assess the efficacy and reliability of vismodegib in the management of adnexal tumors.

Recommended Dose of Vismodegib Therapy

The vismodegib dosage that is approved by the FDA is 150 mg/d until disease progression or the development of intolerable side effects.⁴ Higher dosing regimens were evaluated with 270 mg/d and 540 mg/d. No added therapeutic benefit was noted with the increase in the dose, and no dose-limiting toxic effects were observed.⁴¹

Management of Vismodegib Side Effects

Managing patient expectations is a crucial step in improving dysgeusia. The experience of dysgeusia varies among patients; thus, patients should be instructed to adjust their diets according to their level of dysgeusia, which can be achieved by changing ingredients or dressings used with their diet. This step has been proven to be effective in overcoming vismodegib-related dysgeusia. Also, fluid taste distortion may lead to dehydration and an increase in creatine level. Thus, patients should be encouraged to monitor fluid intake. Moreover, a treatment hiatus of 2 to 8 months results in near-complete improvement of taste distortion.

For muscle spasms, quinine, treatment break for 1 month, gentle exercise of affected areas, or muscle relaxants such as baclofen and temazepam all are effective methods. For vismodegib-related alopecia, managing patient expectations is key; patients should be aware that hair may take 6 to 12 months or even longer to regrow. In addition, shaving less frequently helps improve alopecia.

For gastrointestinal disorders, loperamide with or without codeine phosphate is effective in resolving diarrhea, and metoclopramide is mostly adequate in treating nausea. Another adverse event is weight loss; weight loss of 5% or more of total body weight prompts dietetic referral. If weight loss persists, a treatment break might be needed to regain weight.

Overall, treatment breaks are sufficient to resolve adverse events caused by vismodegib and do not compromise efficacy of treatment. The duration of a treatment break should be considered before initiation. In one clinical trial, a longer treatment break was associated with fewer adverse effects without affecting the efficacy of treatment.⁴²

Conclusion

Vismodegib provides an effective alternative to surgical intervention in the management of BCC. However, patients must be monitored vigilantly, as adverse events are common (>90%).

Basal cell carcinomas (BCCs) are considered the most common cutaneous cancers. Approximately 80% of nonmelanoma skin cancers are BCCs.^1,2 Surgical management is the gold standard for early-stage and localized BCCs; it may include simple excision vs Mohs micrographic surgery.^3,4 However, if left untreated, these lesions can progress to an advanced stage (locally advanced BCC) or infrequently may spread to distant sites (metastatic BCC). In the advanced stage, the lesions are no longer manageable by surgery or radiation therapy.^5,6 Recently, inhibitors targeting the hedgehog (Hh) pathway have shown great promise for these patients. The first drug approved by the US Food and Drug Administration (FDA) for locally advanced and metastatic BCC is vismodegib.⁷ In this article, we provide a clinical review of vismodegib for the management of BCC, including a discussion of the Hh pathway in BCC, adverse effects of vismodegib, use of vismodegib in adnexal skin tumors, recommended doses for vismodegib therapy in BCC, and management of the side effects of treatment.

Hh Pathway in BCC

In embryonic development, the Hh signaling pathway is crucial across a broad spectrum of species, including humans. Various members of the Hh family have been recognized, all working as secreted regulatory proteins.⁸ The name of the Hh signaling pathway is derived from a polypeptide ligand called hedgehog found in some fruit flies. Mutations in the gene led to fruit fly larvae that had a spiky hairy pattern of denticles similar to hedgehogs, leading to the name of this molecule.⁹ The transmembrane protein smoothened (SMO) is the main component of the Hh signaling pathway and initiates a signaling cascade that in turn leads to an increased expression of target genes, such as GLI1. Patched (PTCH), also a transmembrane protein and a cell-surface receptor for the secreted Hh ligand, suppresses the signaling capacity of SMO. Upon binding of the Hh ligand to the PTCH receptor, the suppression of SMO is relieved and a signal is propagated, evoking a cellular response.¹⁰ Molecular and genetic studies have reported that genetic alterations in the Hh signaling pathway are almost universally present in all BCCs, leading to an aberrant activation of the pathway and an uncontrolled proliferation of the basal cells. Frequently, these alterations have been shown to cause loss of function of PTCH homologue 1, which usually acts to inhibit the SMO homologue signaling activity.^11,12

Because of the potential importance of Hh signaling in other solid malignancies and the failure of topical inhibition of SMO,¹³ subsequent studies on the development of Hh pathway inhibitors have mostly focused on the systemic approach. A multitude of Hh pathway inhibitors have been developed thus far, such as SANT1-SANT4, GDC-0449, IPI-926, BMS-833923 (XL139), HhAntag-691, and MK-4101.¹⁴ Many of these inhibitors have been clinically investigated.^13,15,16

Systemic SMO Inhibitor: Vismodegib

Vismodegib was the earliest systemic SMO inhibitor to fulfill early clinical evaluation^15,16 and the first drug to receive FDA approval for the management of advanced or metastatic BCC. Vismodegib is a small-molecule SMO inhibitor used for the management of selected locally advanced BCC and metastatic BCC in adults.^3,17 Although there is a possibility of recurrence following drug withdrawal, vismodegib constitutes a new therapeutic strategy presenting positive benefits to patients. It may provide superior improvement over sunitinib, which has shown efficacy in a few patients; however, the efficacy and tolerance of sunitinib have been shown to be limited.^18,19

Adverse Effects of Vismodegib Therapy

Adverse events with vismodegib use have been reported in 98% of patients (N=491); most of these were mild to moderate.²⁰ However, the frequency of adverse events could prove to be a therapeutic challenge for patients requiring extended treatment. The most frequently reported reversible side effects were muscle spasms (64%), alopecia (62%), weight loss (33%), fatigue (28%), decreased appetite (25%), diarrhea (17%), nausea (16%), dysgeusia (54%), and ageusia (22%).²⁰ In clinical trials, amenorrhea was noticed in 30% (3/10) of females with reproductive potential.² Apart from alopecia and possibly amenorrhea, these side effects are reversible.¹⁷ Alkeraye et al¹⁷ reported 3 clinical cases of persistent alopecia following the use of vismodegib. Amenorrhea is a possible side effect of unknown reversibility.⁷

Vismodegib is a pregnancy category D medication.⁴ Severe birth defects, including craniofacial abnormalities, retardations in normal growth, open perineum, and absence of digital fusion at a corresponding 20% of the recommended daily dose, were found in rat studies. Embryo-fetal death was noted when rats were exposedto concentrations comparable to the recommended human dose.⁴

Hepatic events with the use of vismodegib have been reported. The use of vismodegib in randomized controlled trials resulted in elevation of both alanine aminotransferase and aspartate aminotransferase levels compared with placebo.²¹ Moreover, severe hepatotoxicity with vismodegib has been reported.^22-24 A study conducted by Edwards et al²⁵ concluded that the use of vismodegib in patients with severe liver disease must include thorough risk-benefit assessment, with caution in using other concomitant hepatotoxic medications.

Rare adverse events also have been reported in the literature, including vismodegib-induced pancreatitis in a 79-year-old patient treated for locally advanced, recurrent BCC that was cleared following cessation of therapy.²⁶ Additionally, atypical fibroxanthoma was observed in an 83-year-old patient after 30 days of treatment with vismodegib for multiple BCCs.²⁷ The development of other secondary malignancies, such as squamous cell carcinoma, melanoma, keratoacanthomas, and pilomatricomas, during or after the long-term use of vismodegib also have been described.^28-35

Use of Vismodegib for Adnexal Skin Tumors

The role of the sonic Hh–PTCH pathway in the pathogenesis of adnexal tumors varies in the literature. Some studies propose the involvement of this pathway in the formation of adnexal tumors such as trichoblastoma, trichoepithelioma, and cylindroma, as in BCC. Various lines of evidence support this involvement. Firstly, in mice, the spontaneous generation of numerous BCCs, trichoblastomas, trichoepitheliomas, and cylindromas has been observed following constitutive activation of the sonic Hh–PTCH pathway.³⁶ Secondly, in trichoepitheliomas, there have been positive results in molecular research into the tumor suppressor gene PTCH homologue 1, PTCH1, whose mutations cause constitutive activation of the sonic Hh–PTCH pathway.³⁷ Thirdly, GLI1³⁸ and SOX9³⁹ transcription factors associated with the signaling pathway of sonic Hh–PTCH appear to have increased levels in adnexal carcinomas.¹⁹ Lepesant et al¹⁹ reported a notable clinical response to vismodegib in trichoblastic carcinoma. Baur et al⁴⁰ reported successful treatment of multiple familial trichoepitheliomas with vismodegib. Nonetheless, more studies are required to assess the efficacy and reliability of vismodegib in the management of adnexal tumors.

Recommended Dose of Vismodegib Therapy

The vismodegib dosage that is approved by the FDA is 150 mg/d until disease progression or the development of intolerable side effects.⁴ Higher dosing regimens were evaluated with 270 mg/d and 540 mg/d. No added therapeutic benefit was noted with the increase in the dose, and no dose-limiting toxic effects were observed.⁴¹

Management of Vismodegib Side Effects

Managing patient expectations is a crucial step in improving dysgeusia. The experience of dysgeusia varies among patients; thus, patients should be instructed to adjust their diets according to their level of dysgeusia, which can be achieved by changing ingredients or dressings used with their diet. This step has been proven to be effective in overcoming vismodegib-related dysgeusia. Also, fluid taste distortion may lead to dehydration and an increase in creatine level. Thus, patients should be encouraged to monitor fluid intake. Moreover, a treatment hiatus of 2 to 8 months results in near-complete improvement of taste distortion.

For muscle spasms, quinine, treatment break for 1 month, gentle exercise of affected areas, or muscle relaxants such as baclofen and temazepam all are effective methods. For vismodegib-related alopecia, managing patient expectations is key; patients should be aware that hair may take 6 to 12 months or even longer to regrow. In addition, shaving less frequently helps improve alopecia.

For gastrointestinal disorders, loperamide with or without codeine phosphate is effective in resolving diarrhea, and metoclopramide is mostly adequate in treating nausea. Another adverse event is weight loss; weight loss of 5% or more of total body weight prompts dietetic referral. If weight loss persists, a treatment break might be needed to regain weight.

Overall, treatment breaks are sufficient to resolve adverse events caused by vismodegib and do not compromise efficacy of treatment. The duration of a treatment break should be considered before initiation. In one clinical trial, a longer treatment break was associated with fewer adverse effects without affecting the efficacy of treatment.⁴²

Conclusion

Vismodegib provides an effective alternative to surgical intervention in the management of BCC. However, patients must be monitored vigilantly, as adverse events are common (>90%).

Basal cell carcinomas (BCCs) are considered the most common cutaneous cancers. Approximately 80% of nonmelanoma skin cancers are BCCs.^1,2 Surgical management is the gold standard for early-stage and localized BCCs; it may include simple excision vs Mohs micrographic surgery.^3,4 However, if left untreated, these lesions can progress to an advanced stage (locally advanced BCC) or infrequently may spread to distant sites (metastatic BCC). In the advanced stage, the lesions are no longer manageable by surgery or radiation therapy.^5,6 Recently, inhibitors targeting the hedgehog (Hh) pathway have shown great promise for these patients. The first drug approved by the US Food and Drug Administration (FDA) for locally advanced and metastatic BCC is vismodegib.⁷ In this article, we provide a clinical review of vismodegib for the management of BCC, including a discussion of the Hh pathway in BCC, adverse effects of vismodegib, use of vismodegib in adnexal skin tumors, recommended doses for vismodegib therapy in BCC, and management of the side effects of treatment.

Hh Pathway in BCC

In embryonic development, the Hh signaling pathway is crucial across a broad spectrum of species, including humans. Various members of the Hh family have been recognized, all working as secreted regulatory proteins.⁸ The name of the Hh signaling pathway is derived from a polypeptide ligand called hedgehog found in some fruit flies. Mutations in the gene led to fruit fly larvae that had a spiky hairy pattern of denticles similar to hedgehogs, leading to the name of this molecule.⁹ The transmembrane protein smoothened (SMO) is the main component of the Hh signaling pathway and initiates a signaling cascade that in turn leads to an increased expression of target genes, such as GLI1. Patched (PTCH), also a transmembrane protein and a cell-surface receptor for the secreted Hh ligand, suppresses the signaling capacity of SMO. Upon binding of the Hh ligand to the PTCH receptor, the suppression of SMO is relieved and a signal is propagated, evoking a cellular response.¹⁰ Molecular and genetic studies have reported that genetic alterations in the Hh signaling pathway are almost universally present in all BCCs, leading to an aberrant activation of the pathway and an uncontrolled proliferation of the basal cells. Frequently, these alterations have been shown to cause loss of function of PTCH homologue 1, which usually acts to inhibit the SMO homologue signaling activity.^11,12

Because of the potential importance of Hh signaling in other solid malignancies and the failure of topical inhibition of SMO,¹³ subsequent studies on the development of Hh pathway inhibitors have mostly focused on the systemic approach. A multitude of Hh pathway inhibitors have been developed thus far, such as SANT1-SANT4, GDC-0449, IPI-926, BMS-833923 (XL139), HhAntag-691, and MK-4101.¹⁴ Many of these inhibitors have been clinically investigated.^13,15,16

Systemic SMO Inhibitor: Vismodegib

Vismodegib was the earliest systemic SMO inhibitor to fulfill early clinical evaluation^15,16 and the first drug to receive FDA approval for the management of advanced or metastatic BCC. Vismodegib is a small-molecule SMO inhibitor used for the management of selected locally advanced BCC and metastatic BCC in adults.^3,17 Although there is a possibility of recurrence following drug withdrawal, vismodegib constitutes a new therapeutic strategy presenting positive benefits to patients. It may provide superior improvement over sunitinib, which has shown efficacy in a few patients; however, the efficacy and tolerance of sunitinib have been shown to be limited.^18,19

Adverse Effects of Vismodegib Therapy

Adverse events with vismodegib use have been reported in 98% of patients (N=491); most of these were mild to moderate.²⁰ However, the frequency of adverse events could prove to be a therapeutic challenge for patients requiring extended treatment. The most frequently reported reversible side effects were muscle spasms (64%), alopecia (62%), weight loss (33%), fatigue (28%), decreased appetite (25%), diarrhea (17%), nausea (16%), dysgeusia (54%), and ageusia (22%).²⁰ In clinical trials, amenorrhea was noticed in 30% (3/10) of females with reproductive potential.² Apart from alopecia and possibly amenorrhea, these side effects are reversible.¹⁷ Alkeraye et al¹⁷ reported 3 clinical cases of persistent alopecia following the use of vismodegib. Amenorrhea is a possible side effect of unknown reversibility.⁷

Vismodegib is a pregnancy category D medication.⁴ Severe birth defects, including craniofacial abnormalities, retardations in normal growth, open perineum, and absence of digital fusion at a corresponding 20% of the recommended daily dose, were found in rat studies. Embryo-fetal death was noted when rats were exposedto concentrations comparable to the recommended human dose.⁴

Hepatic events with the use of vismodegib have been reported. The use of vismodegib in randomized controlled trials resulted in elevation of both alanine aminotransferase and aspartate aminotransferase levels compared with placebo.²¹ Moreover, severe hepatotoxicity with vismodegib has been reported.^22-24 A study conducted by Edwards et al²⁵ concluded that the use of vismodegib in patients with severe liver disease must include thorough risk-benefit assessment, with caution in using other concomitant hepatotoxic medications.

Rare adverse events also have been reported in the literature, including vismodegib-induced pancreatitis in a 79-year-old patient treated for locally advanced, recurrent BCC that was cleared following cessation of therapy.²⁶ Additionally, atypical fibroxanthoma was observed in an 83-year-old patient after 30 days of treatment with vismodegib for multiple BCCs.²⁷ The development of other secondary malignancies, such as squamous cell carcinoma, melanoma, keratoacanthomas, and pilomatricomas, during or after the long-term use of vismodegib also have been described.^28-35

Use of Vismodegib for Adnexal Skin Tumors

The role of the sonic Hh–PTCH pathway in the pathogenesis of adnexal tumors varies in the literature. Some studies propose the involvement of this pathway in the formation of adnexal tumors such as trichoblastoma, trichoepithelioma, and cylindroma, as in BCC. Various lines of evidence support this involvement. Firstly, in mice, the spontaneous generation of numerous BCCs, trichoblastomas, trichoepitheliomas, and cylindromas has been observed following constitutive activation of the sonic Hh–PTCH pathway.³⁶ Secondly, in trichoepitheliomas, there have been positive results in molecular research into the tumor suppressor gene PTCH homologue 1, PTCH1, whose mutations cause constitutive activation of the sonic Hh–PTCH pathway.³⁷ Thirdly, GLI1³⁸ and SOX9³⁹ transcription factors associated with the signaling pathway of sonic Hh–PTCH appear to have increased levels in adnexal carcinomas.¹⁹ Lepesant et al¹⁹ reported a notable clinical response to vismodegib in trichoblastic carcinoma. Baur et al⁴⁰ reported successful treatment of multiple familial trichoepitheliomas with vismodegib. Nonetheless, more studies are required to assess the efficacy and reliability of vismodegib in the management of adnexal tumors.

Recommended Dose of Vismodegib Therapy

The vismodegib dosage that is approved by the FDA is 150 mg/d until disease progression or the development of intolerable side effects.⁴ Higher dosing regimens were evaluated with 270 mg/d and 540 mg/d. No added therapeutic benefit was noted with the increase in the dose, and no dose-limiting toxic effects were observed.⁴¹

Management of Vismodegib Side Effects

Managing patient expectations is a crucial step in improving dysgeusia. The experience of dysgeusia varies among patients; thus, patients should be instructed to adjust their diets according to their level of dysgeusia, which can be achieved by changing ingredients or dressings used with their diet. This step has been proven to be effective in overcoming vismodegib-related dysgeusia. Also, fluid taste distortion may lead to dehydration and an increase in creatine level. Thus, patients should be encouraged to monitor fluid intake. Moreover, a treatment hiatus of 2 to 8 months results in near-complete improvement of taste distortion.

For muscle spasms, quinine, treatment break for 1 month, gentle exercise of affected areas, or muscle relaxants such as baclofen and temazepam all are effective methods. For vismodegib-related alopecia, managing patient expectations is key; patients should be aware that hair may take 6 to 12 months or even longer to regrow. In addition, shaving less frequently helps improve alopecia.

For gastrointestinal disorders, loperamide with or without codeine phosphate is effective in resolving diarrhea, and metoclopramide is mostly adequate in treating nausea. Another adverse event is weight loss; weight loss of 5% or more of total body weight prompts dietetic referral. If weight loss persists, a treatment break might be needed to regain weight.

Overall, treatment breaks are sufficient to resolve adverse events caused by vismodegib and do not compromise efficacy of treatment. The duration of a treatment break should be considered before initiation. In one clinical trial, a longer treatment break was associated with fewer adverse effects without affecting the efficacy of treatment.⁴²

Conclusion

Vismodegib provides an effective alternative to surgical intervention in the management of BCC. However, patients must be monitored vigilantly, as adverse events are common (>90%).

Practice Gap

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by inflammatory nodules, abscesses, sinus tracts, fistulae, and scarring, mainly in intertriginous areas. The extent of disease—classified using the Hurley staging system (stages I–III)—helps guide treatment, which includes medical management and surgical intervention in later stages.

First-line treatment of HS includes topical or systemic medications, or both. Surgical therapy typically is reserved for refractory HS in moderate to severe disease (Hurley stages II and III) and is combined with pharmacotherapy. Specifically, clinical management guidelines issued by an expert committee of the United States and Canadian Hidradenitis Suppurativa Foundations recommend excision or deroofing for recurrent nodules and tunnels.¹

Surgical options for HS that are available to the outpatient dermatologist include incision and drainage, electrosurgery, CO₂ laser evaporation, excision, and deroofing (also known as unroofing).² Deroofing is a fairly novel therapy; many dermatologists are unfamiliar with the procedure. A PubMed search of articles indexed for MEDLINE related to HS prior to 2010 revealed only 1 article containing the word deroofing and only 4 articles containing unroofing.

The pathophysiology of HS has important implications for successful treatment. Inflammation of the follicular pilosebaceous unit along with follicular occlusion create challenges with treatment.³ It is postulated that a defect in the glassy membrane of the infra-infundibular wall predisposes the pilosebaceous follicle to lose its structural integrality as pressure builds from plugging of the duct,⁴ which can result in the clinical hallmarks of HS including tunneling tracts, bridging nodules, abscesses, and fistulae that form with lateral expansion of the plugged follicle.

Leaking of the contents of these plugged follicles into surrounding tissue produces an inflammatory response in characteristic HS lesions. Because debris within the lesions moves laterally instead of being able to burst to the surface, the lesions have difficulty fully healing. Unroofing the lesions and removing built-up debris allows them to heal more expediently and quiets the underlying immune response by removing the stimulus.⁴

Herein, we describe the benefits, risks, and surgical process of deroofing for HS.

Technique and Tools

Deroofing is performed under local anesthesia, stepwise as follows:

1. Identify sinus tracts and infiltrate the area with lidocaine (Figure, A).

2. Use a blunt probe to define the borders of the area to be unroofed and to evaluate for any communicating sinus tracts (Figure, B).

3. Remove the roof of underlying abscesses and tracts, using a probe as a guide (Figure, C).

4. Enter through the skin or sinus opening using electrocautery or with a scalpel or scissors; perform blunt dissection.

5. Reflect back the entirety of skin overlying the probed areas and remove the skin to expose the base of the lesion (Figure, D).

6. Explore the exposed base and walls of the lesion with the probe again to assess for hidden tracts; take care not to create false tracts.

7. Debride the surgical wound using curettage or rough gauze grattage to remove remaining inflammatory debris or biofilm. To achieve hemostasis, apply aluminum chloride or ferric chloride. Coat the wound with petroleum jelly and gauze and allow it to heal by secondary intention.

8. Educate the patient on wound care—once-daily gentle cleansing with soap and water, followed by application of a moist dressing—which is similar to wound healing by secondary intention from other causes.^2,4

Practice Implications

A deroofing procedure has many benefits compared to other surgical modalities for the treatment of HS. Deroofing requires only a probe, curette, and electrocautery device, making the procedure more cost-effective than excision, which requires a full tray of equipment and sutures. Furthermore, margins do not need to be taken with deroofing, and no undermining or closure is needed, which saves time during the operation and minimizes the risk for complications, including dehiscence and formation of new sinus tracts.⁴ No specialized equipment, such as a CO₂ laser, is required, which makes deroofing accessible to every clinical dermatologist in any demographic or geographic setting.

Evidence of Benefit—Saylor and colleagues⁵ found that deroofing carries a 12.5% complication rate, which includes postoperative bleeding, hypergranulation tissue, and rarely wound infection. This rate is significantly lower than the 26% complication rate associated with local excision, which includes wound dehiscence, infection, and contracture (P<.001). Deroofing also was found to have an HS recurrence rate of 14.5%, which is significantly less than the 30% recurrence rate seen with local excision (P=.015). Saylor et al⁵ also concluded that incision and drainage was recommended only for immediate relief of HS because of its 100% recurrence rate.

van der Zee² reported on 88 lesions from 44 patients that were treated by surgical deroofing, resulting in an average defect of 3.0 cm in length and a mean healing time of 14 days. The typical outcome was cosmetically acceptable scarring; this finding was supported by a postoperative survey (>1 year), to which 37 of 44 patients responded and assigned an average satisfaction score of 8 (of a possible 10) and a recommendation rate of 90%.²

Procedural Coding—Specific Current Procedural Terminology codes (11450-11471) from the International Classification of Diseases, Tenth Revision, exist for HS deroofing procedures; the applicable code for a given case depends on the final length of the surgical defect. Documentation to support these codes is similar to the note for an excision procedure, taking care to include location, depth, and length of the excision; healing by secondary intention; and the diagnosis of HS.

Final Thoughts

Deroofing is a surgical option that can be beneficial to patients with HS. It is a relatively simple procedure available to any dermatologist, regardless of setting. We encourage dermatologists to consider deroofing, even in patients with Hurley stage II lesions, because it can yield cosmetically acceptable and definitive results, given the variety of therapies available for HS. Deroofing also can be superior to standard excision, especially because of the potential complications with standard excision and quicker operative time with deroofing. As more providers become familiar with the deroofing procedure for HS, further studies can be undertaken to add to the paucity of data about deroofing and how it compares to other surgical treatments.

Practice Gap

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by inflammatory nodules, abscesses, sinus tracts, fistulae, and scarring, mainly in intertriginous areas. The extent of disease—classified using the Hurley staging system (stages I–III)—helps guide treatment, which includes medical management and surgical intervention in later stages.

First-line treatment of HS includes topical or systemic medications, or both. Surgical therapy typically is reserved for refractory HS in moderate to severe disease (Hurley stages II and III) and is combined with pharmacotherapy. Specifically, clinical management guidelines issued by an expert committee of the United States and Canadian Hidradenitis Suppurativa Foundations recommend excision or deroofing for recurrent nodules and tunnels.¹

Surgical options for HS that are available to the outpatient dermatologist include incision and drainage, electrosurgery, CO₂ laser evaporation, excision, and deroofing (also known as unroofing).² Deroofing is a fairly novel therapy; many dermatologists are unfamiliar with the procedure. A PubMed search of articles indexed for MEDLINE related to HS prior to 2010 revealed only 1 article containing the word deroofing and only 4 articles containing unroofing.

The pathophysiology of HS has important implications for successful treatment. Inflammation of the follicular pilosebaceous unit along with follicular occlusion create challenges with treatment.³ It is postulated that a defect in the glassy membrane of the infra-infundibular wall predisposes the pilosebaceous follicle to lose its structural integrality as pressure builds from plugging of the duct,⁴ which can result in the clinical hallmarks of HS including tunneling tracts, bridging nodules, abscesses, and fistulae that form with lateral expansion of the plugged follicle.

Leaking of the contents of these plugged follicles into surrounding tissue produces an inflammatory response in characteristic HS lesions. Because debris within the lesions moves laterally instead of being able to burst to the surface, the lesions have difficulty fully healing. Unroofing the lesions and removing built-up debris allows them to heal more expediently and quiets the underlying immune response by removing the stimulus.⁴

Herein, we describe the benefits, risks, and surgical process of deroofing for HS.

Technique and Tools

Deroofing is performed under local anesthesia, stepwise as follows:

1. Identify sinus tracts and infiltrate the area with lidocaine (Figure, A).

2. Use a blunt probe to define the borders of the area to be unroofed and to evaluate for any communicating sinus tracts (Figure, B).

3. Remove the roof of underlying abscesses and tracts, using a probe as a guide (Figure, C).

4. Enter through the skin or sinus opening using electrocautery or with a scalpel or scissors; perform blunt dissection.

5. Reflect back the entirety of skin overlying the probed areas and remove the skin to expose the base of the lesion (Figure, D).

6. Explore the exposed base and walls of the lesion with the probe again to assess for hidden tracts; take care not to create false tracts.

7. Debride the surgical wound using curettage or rough gauze grattage to remove remaining inflammatory debris or biofilm. To achieve hemostasis, apply aluminum chloride or ferric chloride. Coat the wound with petroleum jelly and gauze and allow it to heal by secondary intention.

8. Educate the patient on wound care—once-daily gentle cleansing with soap and water, followed by application of a moist dressing—which is similar to wound healing by secondary intention from other causes.^2,4

Practice Implications

A deroofing procedure has many benefits compared to other surgical modalities for the treatment of HS. Deroofing requires only a probe, curette, and electrocautery device, making the procedure more cost-effective than excision, which requires a full tray of equipment and sutures. Furthermore, margins do not need to be taken with deroofing, and no undermining or closure is needed, which saves time during the operation and minimizes the risk for complications, including dehiscence and formation of new sinus tracts.⁴ No specialized equipment, such as a CO₂ laser, is required, which makes deroofing accessible to every clinical dermatologist in any demographic or geographic setting.

Evidence of Benefit—Saylor and colleagues⁵ found that deroofing carries a 12.5% complication rate, which includes postoperative bleeding, hypergranulation tissue, and rarely wound infection. This rate is significantly lower than the 26% complication rate associated with local excision, which includes wound dehiscence, infection, and contracture (P<.001). Deroofing also was found to have an HS recurrence rate of 14.5%, which is significantly less than the 30% recurrence rate seen with local excision (P=.015). Saylor et al⁵ also concluded that incision and drainage was recommended only for immediate relief of HS because of its 100% recurrence rate.

van der Zee² reported on 88 lesions from 44 patients that were treated by surgical deroofing, resulting in an average defect of 3.0 cm in length and a mean healing time of 14 days. The typical outcome was cosmetically acceptable scarring; this finding was supported by a postoperative survey (>1 year), to which 37 of 44 patients responded and assigned an average satisfaction score of 8 (of a possible 10) and a recommendation rate of 90%.²

Procedural Coding—Specific Current Procedural Terminology codes (11450-11471) from the International Classification of Diseases, Tenth Revision, exist for HS deroofing procedures; the applicable code for a given case depends on the final length of the surgical defect. Documentation to support these codes is similar to the note for an excision procedure, taking care to include location, depth, and length of the excision; healing by secondary intention; and the diagnosis of HS.

Final Thoughts

Deroofing is a surgical option that can be beneficial to patients with HS. It is a relatively simple procedure available to any dermatologist, regardless of setting. We encourage dermatologists to consider deroofing, even in patients with Hurley stage II lesions, because it can yield cosmetically acceptable and definitive results, given the variety of therapies available for HS. Deroofing also can be superior to standard excision, especially because of the potential complications with standard excision and quicker operative time with deroofing. As more providers become familiar with the deroofing procedure for HS, further studies can be undertaken to add to the paucity of data about deroofing and how it compares to other surgical treatments.

Practice Gap

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by inflammatory nodules, abscesses, sinus tracts, fistulae, and scarring, mainly in intertriginous areas. The extent of disease—classified using the Hurley staging system (stages I–III)—helps guide treatment, which includes medical management and surgical intervention in later stages.

First-line treatment of HS includes topical or systemic medications, or both. Surgical therapy typically is reserved for refractory HS in moderate to severe disease (Hurley stages II and III) and is combined with pharmacotherapy. Specifically, clinical management guidelines issued by an expert committee of the United States and Canadian Hidradenitis Suppurativa Foundations recommend excision or deroofing for recurrent nodules and tunnels.¹

Surgical options for HS that are available to the outpatient dermatologist include incision and drainage, electrosurgery, CO₂ laser evaporation, excision, and deroofing (also known as unroofing).² Deroofing is a fairly novel therapy; many dermatologists are unfamiliar with the procedure. A PubMed search of articles indexed for MEDLINE related to HS prior to 2010 revealed only 1 article containing the word deroofing and only 4 articles containing unroofing.

The pathophysiology of HS has important implications for successful treatment. Inflammation of the follicular pilosebaceous unit along with follicular occlusion create challenges with treatment.³ It is postulated that a defect in the glassy membrane of the infra-infundibular wall predisposes the pilosebaceous follicle to lose its structural integrality as pressure builds from plugging of the duct,⁴ which can result in the clinical hallmarks of HS including tunneling tracts, bridging nodules, abscesses, and fistulae that form with lateral expansion of the plugged follicle.

Leaking of the contents of these plugged follicles into surrounding tissue produces an inflammatory response in characteristic HS lesions. Because debris within the lesions moves laterally instead of being able to burst to the surface, the lesions have difficulty fully healing. Unroofing the lesions and removing built-up debris allows them to heal more expediently and quiets the underlying immune response by removing the stimulus.⁴

Herein, we describe the benefits, risks, and surgical process of deroofing for HS.

Technique and Tools

Deroofing is performed under local anesthesia, stepwise as follows:

1. Identify sinus tracts and infiltrate the area with lidocaine (Figure, A).

2. Use a blunt probe to define the borders of the area to be unroofed and to evaluate for any communicating sinus tracts (Figure, B).

3. Remove the roof of underlying abscesses and tracts, using a probe as a guide (Figure, C).

4. Enter through the skin or sinus opening using electrocautery or with a scalpel or scissors; perform blunt dissection.

5. Reflect back the entirety of skin overlying the probed areas and remove the skin to expose the base of the lesion (Figure, D).

6. Explore the exposed base and walls of the lesion with the probe again to assess for hidden tracts; take care not to create false tracts.

7. Debride the surgical wound using curettage or rough gauze grattage to remove remaining inflammatory debris or biofilm. To achieve hemostasis, apply aluminum chloride or ferric chloride. Coat the wound with petroleum jelly and gauze and allow it to heal by secondary intention.

8. Educate the patient on wound care—once-daily gentle cleansing with soap and water, followed by application of a moist dressing—which is similar to wound healing by secondary intention from other causes.^2,4

Practice Implications

A deroofing procedure has many benefits compared to other surgical modalities for the treatment of HS. Deroofing requires only a probe, curette, and electrocautery device, making the procedure more cost-effective than excision, which requires a full tray of equipment and sutures. Furthermore, margins do not need to be taken with deroofing, and no undermining or closure is needed, which saves time during the operation and minimizes the risk for complications, including dehiscence and formation of new sinus tracts.⁴ No specialized equipment, such as a CO₂ laser, is required, which makes deroofing accessible to every clinical dermatologist in any demographic or geographic setting.

Evidence of Benefit—Saylor and colleagues⁵ found that deroofing carries a 12.5% complication rate, which includes postoperative bleeding, hypergranulation tissue, and rarely wound infection. This rate is significantly lower than the 26% complication rate associated with local excision, which includes wound dehiscence, infection, and contracture (P<.001). Deroofing also was found to have an HS recurrence rate of 14.5%, which is significantly less than the 30% recurrence rate seen with local excision (P=.015). Saylor et al⁵ also concluded that incision and drainage was recommended only for immediate relief of HS because of its 100% recurrence rate.

van der Zee² reported on 88 lesions from 44 patients that were treated by surgical deroofing, resulting in an average defect of 3.0 cm in length and a mean healing time of 14 days. The typical outcome was cosmetically acceptable scarring; this finding was supported by a postoperative survey (>1 year), to which 37 of 44 patients responded and assigned an average satisfaction score of 8 (of a possible 10) and a recommendation rate of 90%.²

Procedural Coding—Specific Current Procedural Terminology codes (11450-11471) from the International Classification of Diseases, Tenth Revision, exist for HS deroofing procedures; the applicable code for a given case depends on the final length of the surgical defect. Documentation to support these codes is similar to the note for an excision procedure, taking care to include location, depth, and length of the excision; healing by secondary intention; and the diagnosis of HS.

Final Thoughts

Deroofing is a surgical option that can be beneficial to patients with HS. It is a relatively simple procedure available to any dermatologist, regardless of setting. We encourage dermatologists to consider deroofing, even in patients with Hurley stage II lesions, because it can yield cosmetically acceptable and definitive results, given the variety of therapies available for HS. Deroofing also can be superior to standard excision, especially because of the potential complications with standard excision and quicker operative time with deroofing. As more providers become familiar with the deroofing procedure for HS, further studies can be undertaken to add to the paucity of data about deroofing and how it compares to other surgical treatments.

To the Editor:

Cutaneous myiasis is a skin infestation with dipterous larvae that feed on the host’s tissue and cause a wide range of manifestations depending on the location of infestation. Cutaneous myiasis, which includes furuncular, wound, and migratory types, is the most common clinical form of this condition.¹ It is endemic to tropical and subtropical areas and is not common in the United States, thus it can pose a diagnostic challenge when presenting in nonendemic areas. We present the case of a woman from Michigan who acquired furuncular myiasis without travel history to a tropical or subtropical locale.

A 72-year-old woman presented to our clinic with a chief concern of a burning, pruritic, migratory skin lesion on the left arm of approximately 1 week’s duration. She had a medical history of squamous cell carcinoma, keratoacanthoma, and multiple tick bites. She reported that the lesion started on the distal aspect of the left arm as an eraser-sized, perfectly round, raised bruise with a dark pepperlike bump in the center. The lesion then spread proximally over the course of 1 week, creating 3 more identical lesions. As one lesion resolved, a new lesion appeared approximately 2 to 4 cm proximal to the preceding lesion. The patient had traveled to England, Scotland, and Ireland 2 months prior but otherwise denied leaving the state of Michigan. She reported frequent exposure to gardens, meadows, and wetlands in search of milkweed and monarch butterfly larvae that she raises in northeast Michigan. She denied any recent illness or associated systemic symptoms. Initial evaluation by a primary care physician resulted in a diagnosis of a furuncle or tick bite; she completed a 10-day course of amoxicillin and a methylprednisolone dose pack without improvement.

Physical examination revealed a 1-cm, firm, violaceous nodule with a small distinct central punctum and surrounding erythema on the proximal aspect of the left arm. Dermoscopy revealed a pulsating motion and expulsion of serosanguineous fluid from the central punctum (Figure 1). Further inspection of the patient’s left arm exposed several noninflammatory puncta distal to the primary lesion spaced at 2- to 4-cm intervals.

Gross examination of a 6-mm punch biopsy from the primary inflammatory nodule uncovered a small, motile, gray-white larval organism in the inferior portion of the specimen (Figure 2). Histopathology revealed superficial and deep eosinophil-rich inflammation, fibrosis, and hemorrhage. There was a complex wedge-shaped organism with extensive internal muscle bounded by a thin cuticle bearing rows of chitinous hooklets located at one side within the deep dermis (Figure 3). The findings were consistent with a diagnosis of cutaneous myiasis. No further treatment was required, as the organism was completely excised with the biopsy.

The most common causative agents of furuncular myiasis obtained from travelers returning from Mexico and Central and South America are Dermatobia hominis and Cordylobia anthropophaga. Cases of furuncular myiasis acquired in the United States without recent foreign travel are rare. Most of these cases are caused by larvae of the Cuterebra species (also known as the rabbit botfly or rodent botfly).² In a 2003 literature review by Safdar et al³ on 56 cases of furuncular myiasis in the United States, the median age of patients was 14 years, 87% of cases occurred in August and September, and most involved exposure in rural or suburban settings; 53% of cases presented in the northeastern United States.

Furuncular myiasis occurs when the organism’s ova are deposited on the skin of a human host by the parent organism or a mosquito vector. The heat of the skin causes the eggs to hatch and the dipteran larvae must penetrate the skin within 20 days.¹ Signs of infection typically are seen 6 to 10 days after infestation.³ The larvae then feed on human tissue and burrow deep in the dermis, forming an erythematous furunculoid nodule containing one or multiple maggots. After 5 to 10 weeks, the adult larvae drop to the ground, where they mature into adult organisms in the soil.¹

The most reported symptoms of furuncular myiasis include pruritus, pain, and movement sensation, typically occurring suddenly at night.⁴ The most common presentation is a furunclelike lesion that exudes serosanguineous or purulent fluid,¹ but there have been reports of vesicular, bullous, pustular, erosive, ecchymotic, and ulcerative lesions.⁵Dermatobia hominis usually presents on an exposed site, such as the scalp, face, and extremities. It may present with paroxysmal episodes of lancinating pain. Over time, the lesion usually heals without a scar, though hyperpigmentation and scarring can occur. The most reported complication is secondary bacterial infection.⁴ Local lymphadenopathy or systemic symptoms should raise concern for infection. Staphylococcus aureus and group B Streptococcus have been cultured from lesions.^6,7

The differential diagnosis for myiasis should include furuncle, insect bite, insect prurigo, pyoderma, inflamed cyst, and tungiasis. Myiasis also can present similarly to severe soft tissue infections or cellulitis. If located on the breasts, it can be mistaken for periductal mastitis, a benign mass with microcalcification, or inflammatory carcinoma. Lastly, due to pain, erythema, pruritus, small vesicles, and crusting, it may be confused for herpes simplex virus.¹

Furuncular myiasis typically is diagnosed based on clinical presentation, especially in endemic regions. In nonendemic areas, the patient’s history may reveal recent travel or predisposition to myiasis. In cases where there is uncertainty, dermoscopy may be used to identify the maggot in the lesion, or ultrasonography can be used to confirm myiasis through the detection of larval movement.⁸ Dermoscopy will reveal a furuncular lesion with a central opening surrounded by dilated blood vessels and a yellowish structure with black barblike spines.⁹ Within the dermis is a fibrous cystic sinus tract containing the dipteran larva. Laboratory studies typically are unremarkable. In chronic cases, a complete blood cell count and other laboratory tests may show systemic inflammation, peripheral eosinophilia, and elevated IgE.¹⁰ Biopsies of furuncular myiasis are not necessary for diagnosis. Histopathology reveals an ulcerated epidermis with or without hyperkeratosis and an inflammatory infiltrate composed of lymphocytes and neutrophils with eosinophils, fibroblasts, histiocytes, basophils, mast cells, plasma cells, and Langerhans cells within the dermis and subcutis.¹¹

There are various approaches to treating furuncular myiasis, with the goal of complete removal of the larva and prevention of secondary infection. One treatment option is to apply a toxic substance to the larva, effectively killing it. Another approach is to force the larva to emerge via localized hypoxia, which can be done by occluding the punctum of the lesion for at least 24 hours. A complication of this method is suffocation of the larva without migration, leading to incomplete extraction and secondary infection.¹ A third method is to surgically remove the larva, which allows for debridement of necrotic tissue surrounding the lesion if present.¹² Ultrasonography also can be used therapeutically to aid in the removal of the larvae. The last method is to inject lidocaine into the base of the lesion, forcing the larva out of the punctum via fluid pressure.¹³ Oral treatments such as ivermectin are not recommended because they can result in the death of larvae within the lesion, leading to an inflammatory response.⁸

Furuncular myiasis is a form of cutaneous larvae infestation not commonly seen in individuals who do not live or travel in endemic, tropical, and subtropical regions. Diagnosis is based on clinical presentation, with imaging and laboratory studies available to supplement in unclear or atypical manifestations. Treatment involves complete removal of the larva, typically through forced evacuation via hypoxia or through surgical removal. Most cases resolve without notable scarring or other sequelae; however, in those who do have complications, the most common is secondary bacterial infection. Our patient’s absence of notable travel history and frequent environmental exposure in Michigan led us to believe the organism was from a domestic source. Our case underlines the importance of a thorough history and clinical examination of furuncular lesions including the use of dermoscopy to yield an appropriate diagnosis and treatment plan.

To the Editor:

Cutaneous myiasis is a skin infestation with dipterous larvae that feed on the host’s tissue and cause a wide range of manifestations depending on the location of infestation. Cutaneous myiasis, which includes furuncular, wound, and migratory types, is the most common clinical form of this condition.¹ It is endemic to tropical and subtropical areas and is not common in the United States, thus it can pose a diagnostic challenge when presenting in nonendemic areas. We present the case of a woman from Michigan who acquired furuncular myiasis without travel history to a tropical or subtropical locale.

A 72-year-old woman presented to our clinic with a chief concern of a burning, pruritic, migratory skin lesion on the left arm of approximately 1 week’s duration. She had a medical history of squamous cell carcinoma, keratoacanthoma, and multiple tick bites. She reported that the lesion started on the distal aspect of the left arm as an eraser-sized, perfectly round, raised bruise with a dark pepperlike bump in the center. The lesion then spread proximally over the course of 1 week, creating 3 more identical lesions. As one lesion resolved, a new lesion appeared approximately 2 to 4 cm proximal to the preceding lesion. The patient had traveled to England, Scotland, and Ireland 2 months prior but otherwise denied leaving the state of Michigan. She reported frequent exposure to gardens, meadows, and wetlands in search of milkweed and monarch butterfly larvae that she raises in northeast Michigan. She denied any recent illness or associated systemic symptoms. Initial evaluation by a primary care physician resulted in a diagnosis of a furuncle or tick bite; she completed a 10-day course of amoxicillin and a methylprednisolone dose pack without improvement.

Physical examination revealed a 1-cm, firm, violaceous nodule with a small distinct central punctum and surrounding erythema on the proximal aspect of the left arm. Dermoscopy revealed a pulsating motion and expulsion of serosanguineous fluid from the central punctum (Figure 1). Further inspection of the patient’s left arm exposed several noninflammatory puncta distal to the primary lesion spaced at 2- to 4-cm intervals.

Gross examination of a 6-mm punch biopsy from the primary inflammatory nodule uncovered a small, motile, gray-white larval organism in the inferior portion of the specimen (Figure 2). Histopathology revealed superficial and deep eosinophil-rich inflammation, fibrosis, and hemorrhage. There was a complex wedge-shaped organism with extensive internal muscle bounded by a thin cuticle bearing rows of chitinous hooklets located at one side within the deep dermis (Figure 3). The findings were consistent with a diagnosis of cutaneous myiasis. No further treatment was required, as the organism was completely excised with the biopsy.

The most common causative agents of furuncular myiasis obtained from travelers returning from Mexico and Central and South America are Dermatobia hominis and Cordylobia anthropophaga. Cases of furuncular myiasis acquired in the United States without recent foreign travel are rare. Most of these cases are caused by larvae of the Cuterebra species (also known as the rabbit botfly or rodent botfly).² In a 2003 literature review by Safdar et al³ on 56 cases of furuncular myiasis in the United States, the median age of patients was 14 years, 87% of cases occurred in August and September, and most involved exposure in rural or suburban settings; 53% of cases presented in the northeastern United States.

Furuncular myiasis occurs when the organism’s ova are deposited on the skin of a human host by the parent organism or a mosquito vector. The heat of the skin causes the eggs to hatch and the dipteran larvae must penetrate the skin within 20 days.¹ Signs of infection typically are seen 6 to 10 days after infestation.³ The larvae then feed on human tissue and burrow deep in the dermis, forming an erythematous furunculoid nodule containing one or multiple maggots. After 5 to 10 weeks, the adult larvae drop to the ground, where they mature into adult organisms in the soil.¹

The most reported symptoms of furuncular myiasis include pruritus, pain, and movement sensation, typically occurring suddenly at night.⁴ The most common presentation is a furunclelike lesion that exudes serosanguineous or purulent fluid,¹ but there have been reports of vesicular, bullous, pustular, erosive, ecchymotic, and ulcerative lesions.⁵Dermatobia hominis usually presents on an exposed site, such as the scalp, face, and extremities. It may present with paroxysmal episodes of lancinating pain. Over time, the lesion usually heals without a scar, though hyperpigmentation and scarring can occur. The most reported complication is secondary bacterial infection.⁴ Local lymphadenopathy or systemic symptoms should raise concern for infection. Staphylococcus aureus and group B Streptococcus have been cultured from lesions.^6,7

The differential diagnosis for myiasis should include furuncle, insect bite, insect prurigo, pyoderma, inflamed cyst, and tungiasis. Myiasis also can present similarly to severe soft tissue infections or cellulitis. If located on the breasts, it can be mistaken for periductal mastitis, a benign mass with microcalcification, or inflammatory carcinoma. Lastly, due to pain, erythema, pruritus, small vesicles, and crusting, it may be confused for herpes simplex virus.¹

Furuncular myiasis typically is diagnosed based on clinical presentation, especially in endemic regions. In nonendemic areas, the patient’s history may reveal recent travel or predisposition to myiasis. In cases where there is uncertainty, dermoscopy may be used to identify the maggot in the lesion, or ultrasonography can be used to confirm myiasis through the detection of larval movement.⁸ Dermoscopy will reveal a furuncular lesion with a central opening surrounded by dilated blood vessels and a yellowish structure with black barblike spines.⁹ Within the dermis is a fibrous cystic sinus tract containing the dipteran larva. Laboratory studies typically are unremarkable. In chronic cases, a complete blood cell count and other laboratory tests may show systemic inflammation, peripheral eosinophilia, and elevated IgE.¹⁰ Biopsies of furuncular myiasis are not necessary for diagnosis. Histopathology reveals an ulcerated epidermis with or without hyperkeratosis and an inflammatory infiltrate composed of lymphocytes and neutrophils with eosinophils, fibroblasts, histiocytes, basophils, mast cells, plasma cells, and Langerhans cells within the dermis and subcutis.¹¹

There are various approaches to treating furuncular myiasis, with the goal of complete removal of the larva and prevention of secondary infection. One treatment option is to apply a toxic substance to the larva, effectively killing it. Another approach is to force the larva to emerge via localized hypoxia, which can be done by occluding the punctum of the lesion for at least 24 hours. A complication of this method is suffocation of the larva without migration, leading to incomplete extraction and secondary infection.¹ A third method is to surgically remove the larva, which allows for debridement of necrotic tissue surrounding the lesion if present.¹² Ultrasonography also can be used therapeutically to aid in the removal of the larvae. The last method is to inject lidocaine into the base of the lesion, forcing the larva out of the punctum via fluid pressure.¹³ Oral treatments such as ivermectin are not recommended because they can result in the death of larvae within the lesion, leading to an inflammatory response.⁸

Furuncular myiasis is a form of cutaneous larvae infestation not commonly seen in individuals who do not live or travel in endemic, tropical, and subtropical regions. Diagnosis is based on clinical presentation, with imaging and laboratory studies available to supplement in unclear or atypical manifestations. Treatment involves complete removal of the larva, typically through forced evacuation via hypoxia or through surgical removal. Most cases resolve without notable scarring or other sequelae; however, in those who do have complications, the most common is secondary bacterial infection. Our patient’s absence of notable travel history and frequent environmental exposure in Michigan led us to believe the organism was from a domestic source. Our case underlines the importance of a thorough history and clinical examination of furuncular lesions including the use of dermoscopy to yield an appropriate diagnosis and treatment plan.

To the Editor:

Cutaneous myiasis is a skin infestation with dipterous larvae that feed on the host’s tissue and cause a wide range of manifestations depending on the location of infestation. Cutaneous myiasis, which includes furuncular, wound, and migratory types, is the most common clinical form of this condition.¹ It is endemic to tropical and subtropical areas and is not common in the United States, thus it can pose a diagnostic challenge when presenting in nonendemic areas. We present the case of a woman from Michigan who acquired furuncular myiasis without travel history to a tropical or subtropical locale.

A 72-year-old woman presented to our clinic with a chief concern of a burning, pruritic, migratory skin lesion on the left arm of approximately 1 week’s duration. She had a medical history of squamous cell carcinoma, keratoacanthoma, and multiple tick bites. She reported that the lesion started on the distal aspect of the left arm as an eraser-sized, perfectly round, raised bruise with a dark pepperlike bump in the center. The lesion then spread proximally over the course of 1 week, creating 3 more identical lesions. As one lesion resolved, a new lesion appeared approximately 2 to 4 cm proximal to the preceding lesion. The patient had traveled to England, Scotland, and Ireland 2 months prior but otherwise denied leaving the state of Michigan. She reported frequent exposure to gardens, meadows, and wetlands in search of milkweed and monarch butterfly larvae that she raises in northeast Michigan. She denied any recent illness or associated systemic symptoms. Initial evaluation by a primary care physician resulted in a diagnosis of a furuncle or tick bite; she completed a 10-day course of amoxicillin and a methylprednisolone dose pack without improvement.

Physical examination revealed a 1-cm, firm, violaceous nodule with a small distinct central punctum and surrounding erythema on the proximal aspect of the left arm. Dermoscopy revealed a pulsating motion and expulsion of serosanguineous fluid from the central punctum (Figure 1). Further inspection of the patient’s left arm exposed several noninflammatory puncta distal to the primary lesion spaced at 2- to 4-cm intervals.

Gross examination of a 6-mm punch biopsy from the primary inflammatory nodule uncovered a small, motile, gray-white larval organism in the inferior portion of the specimen (Figure 2). Histopathology revealed superficial and deep eosinophil-rich inflammation, fibrosis, and hemorrhage. There was a complex wedge-shaped organism with extensive internal muscle bounded by a thin cuticle bearing rows of chitinous hooklets located at one side within the deep dermis (Figure 3). The findings were consistent with a diagnosis of cutaneous myiasis. No further treatment was required, as the organism was completely excised with the biopsy.

The most common causative agents of furuncular myiasis obtained from travelers returning from Mexico and Central and South America are Dermatobia hominis and Cordylobia anthropophaga. Cases of furuncular myiasis acquired in the United States without recent foreign travel are rare. Most of these cases are caused by larvae of the Cuterebra species (also known as the rabbit botfly or rodent botfly).² In a 2003 literature review by Safdar et al³ on 56 cases of furuncular myiasis in the United States, the median age of patients was 14 years, 87% of cases occurred in August and September, and most involved exposure in rural or suburban settings; 53% of cases presented in the northeastern United States.

Furuncular myiasis occurs when the organism’s ova are deposited on the skin of a human host by the parent organism or a mosquito vector. The heat of the skin causes the eggs to hatch and the dipteran larvae must penetrate the skin within 20 days.¹ Signs of infection typically are seen 6 to 10 days after infestation.³ The larvae then feed on human tissue and burrow deep in the dermis, forming an erythematous furunculoid nodule containing one or multiple maggots. After 5 to 10 weeks, the adult larvae drop to the ground, where they mature into adult organisms in the soil.¹

The most reported symptoms of furuncular myiasis include pruritus, pain, and movement sensation, typically occurring suddenly at night.⁴ The most common presentation is a furunclelike lesion that exudes serosanguineous or purulent fluid,¹ but there have been reports of vesicular, bullous, pustular, erosive, ecchymotic, and ulcerative lesions.⁵Dermatobia hominis usually presents on an exposed site, such as the scalp, face, and extremities. It may present with paroxysmal episodes of lancinating pain. Over time, the lesion usually heals without a scar, though hyperpigmentation and scarring can occur. The most reported complication is secondary bacterial infection.⁴ Local lymphadenopathy or systemic symptoms should raise concern for infection. Staphylococcus aureus and group B Streptococcus have been cultured from lesions.^6,7

The differential diagnosis for myiasis should include furuncle, insect bite, insect prurigo, pyoderma, inflamed cyst, and tungiasis. Myiasis also can present similarly to severe soft tissue infections or cellulitis. If located on the breasts, it can be mistaken for periductal mastitis, a benign mass with microcalcification, or inflammatory carcinoma. Lastly, due to pain, erythema, pruritus, small vesicles, and crusting, it may be confused for herpes simplex virus.¹

Furuncular myiasis typically is diagnosed based on clinical presentation, especially in endemic regions. In nonendemic areas, the patient’s history may reveal recent travel or predisposition to myiasis. In cases where there is uncertainty, dermoscopy may be used to identify the maggot in the lesion, or ultrasonography can be used to confirm myiasis through the detection of larval movement.⁸ Dermoscopy will reveal a furuncular lesion with a central opening surrounded by dilated blood vessels and a yellowish structure with black barblike spines.⁹ Within the dermis is a fibrous cystic sinus tract containing the dipteran larva. Laboratory studies typically are unremarkable. In chronic cases, a complete blood cell count and other laboratory tests may show systemic inflammation, peripheral eosinophilia, and elevated IgE.¹⁰ Biopsies of furuncular myiasis are not necessary for diagnosis. Histopathology reveals an ulcerated epidermis with or without hyperkeratosis and an inflammatory infiltrate composed of lymphocytes and neutrophils with eosinophils, fibroblasts, histiocytes, basophils, mast cells, plasma cells, and Langerhans cells within the dermis and subcutis.¹¹

There are various approaches to treating furuncular myiasis, with the goal of complete removal of the larva and prevention of secondary infection. One treatment option is to apply a toxic substance to the larva, effectively killing it. Another approach is to force the larva to emerge via localized hypoxia, which can be done by occluding the punctum of the lesion for at least 24 hours. A complication of this method is suffocation of the larva without migration, leading to incomplete extraction and secondary infection.¹ A third method is to surgically remove the larva, which allows for debridement of necrotic tissue surrounding the lesion if present.¹² Ultrasonography also can be used therapeutically to aid in the removal of the larvae. The last method is to inject lidocaine into the base of the lesion, forcing the larva out of the punctum via fluid pressure.¹³ Oral treatments such as ivermectin are not recommended because they can result in the death of larvae within the lesion, leading to an inflammatory response.⁸

Furuncular myiasis is a form of cutaneous larvae infestation not commonly seen in individuals who do not live or travel in endemic, tropical, and subtropical regions. Diagnosis is based on clinical presentation, with imaging and laboratory studies available to supplement in unclear or atypical manifestations. Treatment involves complete removal of the larva, typically through forced evacuation via hypoxia or through surgical removal. Most cases resolve without notable scarring or other sequelae; however, in those who do have complications, the most common is secondary bacterial infection. Our patient’s absence of notable travel history and frequent environmental exposure in Michigan led us to believe the organism was from a domestic source. Our case underlines the importance of a thorough history and clinical examination of furuncular lesions including the use of dermoscopy to yield an appropriate diagnosis and treatment plan.

To the Editor:

Ultra-late melanoma recurrence represents a minority of cases in which the quiescent period lasts longer than 15 years, and epidemiologic studies have reported recurrence rates of 6% to 10% during the ultra-late period.¹ Even more uncommon are cases that span many decades (eg, >30 years), but all are useful in understanding the cellular behavior leading to the reactivation of fully excised melanomas. Few cases have been reported in which recurrence occurs more than 35 years after the original diagnosis of melanoma. Unfortunately, mechanisms underlying this long stable quiescence and subsequent reactivation are poorly understood, which is why it is important to identify and document cases. We present a case of local recurrence of cutaneous melanoma on the patient’s lower back after a 49-year disease-free period.

A 78-year-old White woman presented to a private dermatology office for a full-body skin examination. She had a medical history of a cutaneous melanoma that had been removed on the lower back 49 years prior; Parkinson disease of 10 years’ duration; and an enlarged thyroid nodule with decreased thyrotropin and hyperthyroidism, atrial fibrillation, mitral valve prolapse, osteoarthritis in the knees, and actinic keratoses, all of which were chronic conditions lasting years to decades. She was taking several medications for these medical conditions. Her surgical history included a hysterectomy, hip replacement, hernia repair, cardioversion, and tonsillectomy in childhood. Her family medical history included breast cancer in her paternal grandmother and aunt; hypertension in her father; and sarcoma in her mother at 78 years of age, which initially was identified in the sacrum and metastasized to the lungs causing death. No family history of melanoma or other skin cancers was reported. Prior to the original diagnosis of melanoma at 29 years of age, she had no history of skin cancer or any other medical condition other than acne. The patient did report spending a great deal of time in the sun during high school.

The patient reported developing the original cutaneous melanoma during her second pregnancy at 29 years of age and recalled that it was excised with wide margins. There had been a mole on her back that was present for years but changed in size during pregnancy, prompting the original visit to the primary care physician for evaluation. Remarkably, the original pathology report was obtained from the patient and revealed a specimen consisting of a 3.7×1.7-cm skin ellipse averaging 0.7 cm in thickness. In the center of the specimen was a 0.6-cm, round, raised, pigmented lesion that revealed moderately frequent mitoses on microscopic evaluation. It was determined by the pathologist to be a malignant tumor, and the report stated that the surgical margins appeared clear.

Physical examination at the current presentation 49 years later revealed an even-bordered 2-mm black macule that was located approximately 1 cm from the original melanoma excision scar line (Figure). A biopsy was performed and sent to a dermatopathologist. Microscopic evaluation revealed nests, islands, and sheets of atypical epithelioid melanocytes extending through the dermis between collagen bundles. The melanocytes varied in size and shape with moderate nuclear pleomorphism present. Scattered mitotic figures and necrotic melanocytes were present, which most likely represented cutaneous satellite metastases of melanoma. Subsequent chest radiography, full-body positron emission tomography, and standard laboratory blood tests were unremarkable except for an enlarged right thyroid gland and moderate cardiomegaly. The patient was sent to a surgical oncologist for excision with wide surgical margins, and she elected not to have a sentinel lymph node biopsy. At follow-up 3, 6, 12, and 24 months later, there were no signs of recurrence based on direct clinical examination. The patient subsequently was lost to follow-up.

Recurrence rates of melanoma vary by stage and age at diagnosis, but prior studies have reported a recurrence rate of approximately 6% after 10 or more years following the initial diagnosis.² Ultra-late recurrences of approximately 4 decades or more are extremely rare. A PubMed search of articles indexed for MEDLINE using the terms melanoma and ultra-late recurrence revealed 4 reported cases with a quiescent period of 38 or more years.^3-6 All cases were metastatic melanomas in women; spanned 38, 40, 41, and 45 years from the initial melanoma diagnosis to recurrence; and all of the recurrences except one were regional or distal metastatic lesions (eg, lymph node, brain). In one case, both the original and recurrent lesions occurred on the left elbow.⁶ The original lesions occurred on the legs, elbow, and back of the neck, and there were no notable concomitant medical conditions. The patients were aged 72, 73, 73, and 84 years at recurrence.^3-6 However, generalizations from these cases are limited given the potential for selection bias (eg, men may be less likely to visit a clinic for follow-up and nevi examination) and the likelihood that many cases of ultra-late melanoma recurrence are unrecognized or unreported.

More recently, genomic analyses on melanoma lesions occurring 30 years apart confirmed that the second lesion was indeed a recurrence, although with numerous additional mutations.⁷ The specific mechanisms underlying the dormancy and subsequent reemergence of metastatic lesions are unclear, but there may be aberrations in the skin beyond histopathologic margins that represent an early phase of disease that are histologically unrecognizable and may lay dormant for many years before reemerging in response to external or immunologic changes.⁸ Alternatively, recurrences may be associated with lymphatic or hematogenous emboli, or there may be a tendency for melanomas to metastasize to inflamed or scarred tissue representing a tropism of the malignant melanocytes.⁹

It also is worth highlighting the concomitant diagnosis of Parkinson disease in our patient. In recent years, Parkinson disease has been linked to melanoma in both epidemiologic and genetic studies. For example, one large-scale study found a 50% increased risk for developing Parkinson disease in patients with melanoma (and vice versa), and this finding has been replicated in other studies.¹⁰ Moreover, patients with Parkinson disease have a 2-fold increase in their risk for developing melanoma, demonstrating that it is a bidirectional pathway. Not surprisingly, associations between melanin and neuromelanin pathways have been identified as a potential link between these diseases, and scientists are in the process of understanding the genetic components of both.¹⁰ It is unknown if specific genetic mutations contributed to both diseases in our case, but follow-up genetic testing on the recurrent melanoma specimen currently is being pursued.

The 49-year quiescent period in our case of recurrent cutaneous malignant melanoma potentially represents the longest ultra-late recurrence of melanoma in the literature to date based on a review of indexed publications. Moreover, it is relatively unique compared to other similar cases in that the recurrence was within a centimeter of the original excisional scar. Most metastases occur in locoregional lymph nodes or the lungs³; therefore, it is unusual to find one so close to the original lesion, especially one that occurred decades later. Factors associated with ultra-late recurrences are unknown, primarily because of the rarity of these cases as well as the biases and other factors that limit existing studies. However, genetic sequencing may provide information regarding these factors and related processes. Genetic sequencing specifically points to a small cell group remaining after excision of the primary tumor, which mutates while proliferating. Low antigenicity and tolerance to immunity during the quiescent period may explain the long duration of dormancy.⁶ More recently, there have been efforts to identify immunohistochemical signatures that may predict late recurrences, though the data are preliminary in nature.¹¹

Given the latency period and location of the recurrence, our case demonstrates that even fully excised melanomas may recur locally many decades later, hence patients should be aware of the importance of a lifetime of vigilance after being diagnosed with melanoma.

To the Editor:

Ultra-late melanoma recurrence represents a minority of cases in which the quiescent period lasts longer than 15 years, and epidemiologic studies have reported recurrence rates of 6% to 10% during the ultra-late period.¹ Even more uncommon are cases that span many decades (eg, >30 years), but all are useful in understanding the cellular behavior leading to the reactivation of fully excised melanomas. Few cases have been reported in which recurrence occurs more than 35 years after the original diagnosis of melanoma. Unfortunately, mechanisms underlying this long stable quiescence and subsequent reactivation are poorly understood, which is why it is important to identify and document cases. We present a case of local recurrence of cutaneous melanoma on the patient’s lower back after a 49-year disease-free period.

A 78-year-old White woman presented to a private dermatology office for a full-body skin examination. She had a medical history of a cutaneous melanoma that had been removed on the lower back 49 years prior; Parkinson disease of 10 years’ duration; and an enlarged thyroid nodule with decreased thyrotropin and hyperthyroidism, atrial fibrillation, mitral valve prolapse, osteoarthritis in the knees, and actinic keratoses, all of which were chronic conditions lasting years to decades. She was taking several medications for these medical conditions. Her surgical history included a hysterectomy, hip replacement, hernia repair, cardioversion, and tonsillectomy in childhood. Her family medical history included breast cancer in her paternal grandmother and aunt; hypertension in her father; and sarcoma in her mother at 78 years of age, which initially was identified in the sacrum and metastasized to the lungs causing death. No family history of melanoma or other skin cancers was reported. Prior to the original diagnosis of melanoma at 29 years of age, she had no history of skin cancer or any other medical condition other than acne. The patient did report spending a great deal of time in the sun during high school.

The patient reported developing the original cutaneous melanoma during her second pregnancy at 29 years of age and recalled that it was excised with wide margins. There had been a mole on her back that was present for years but changed in size during pregnancy, prompting the original visit to the primary care physician for evaluation. Remarkably, the original pathology report was obtained from the patient and revealed a specimen consisting of a 3.7×1.7-cm skin ellipse averaging 0.7 cm in thickness. In the center of the specimen was a 0.6-cm, round, raised, pigmented lesion that revealed moderately frequent mitoses on microscopic evaluation. It was determined by the pathologist to be a malignant tumor, and the report stated that the surgical margins appeared clear.

Physical examination at the current presentation 49 years later revealed an even-bordered 2-mm black macule that was located approximately 1 cm from the original melanoma excision scar line (Figure). A biopsy was performed and sent to a dermatopathologist. Microscopic evaluation revealed nests, islands, and sheets of atypical epithelioid melanocytes extending through the dermis between collagen bundles. The melanocytes varied in size and shape with moderate nuclear pleomorphism present. Scattered mitotic figures and necrotic melanocytes were present, which most likely represented cutaneous satellite metastases of melanoma. Subsequent chest radiography, full-body positron emission tomography, and standard laboratory blood tests were unremarkable except for an enlarged right thyroid gland and moderate cardiomegaly. The patient was sent to a surgical oncologist for excision with wide surgical margins, and she elected not to have a sentinel lymph node biopsy. At follow-up 3, 6, 12, and 24 months later, there were no signs of recurrence based on direct clinical examination. The patient subsequently was lost to follow-up.

Recurrence rates of melanoma vary by stage and age at diagnosis, but prior studies have reported a recurrence rate of approximately 6% after 10 or more years following the initial diagnosis.² Ultra-late recurrences of approximately 4 decades or more are extremely rare. A PubMed search of articles indexed for MEDLINE using the terms melanoma and ultra-late recurrence revealed 4 reported cases with a quiescent period of 38 or more years.^3-6 All cases were metastatic melanomas in women; spanned 38, 40, 41, and 45 years from the initial melanoma diagnosis to recurrence; and all of the recurrences except one were regional or distal metastatic lesions (eg, lymph node, brain). In one case, both the original and recurrent lesions occurred on the left elbow.⁶ The original lesions occurred on the legs, elbow, and back of the neck, and there were no notable concomitant medical conditions. The patients were aged 72, 73, 73, and 84 years at recurrence.^3-6 However, generalizations from these cases are limited given the potential for selection bias (eg, men may be less likely to visit a clinic for follow-up and nevi examination) and the likelihood that many cases of ultra-late melanoma recurrence are unrecognized or unreported.

More recently, genomic analyses on melanoma lesions occurring 30 years apart confirmed that the second lesion was indeed a recurrence, although with numerous additional mutations.⁷ The specific mechanisms underlying the dormancy and subsequent reemergence of metastatic lesions are unclear, but there may be aberrations in the skin beyond histopathologic margins that represent an early phase of disease that are histologically unrecognizable and may lay dormant for many years before reemerging in response to external or immunologic changes.⁸ Alternatively, recurrences may be associated with lymphatic or hematogenous emboli, or there may be a tendency for melanomas to metastasize to inflamed or scarred tissue representing a tropism of the malignant melanocytes.⁹

It also is worth highlighting the concomitant diagnosis of Parkinson disease in our patient. In recent years, Parkinson disease has been linked to melanoma in both epidemiologic and genetic studies. For example, one large-scale study found a 50% increased risk for developing Parkinson disease in patients with melanoma (and vice versa), and this finding has been replicated in other studies.¹⁰ Moreover, patients with Parkinson disease have a 2-fold increase in their risk for developing melanoma, demonstrating that it is a bidirectional pathway. Not surprisingly, associations between melanin and neuromelanin pathways have been identified as a potential link between these diseases, and scientists are in the process of understanding the genetic components of both.¹⁰ It is unknown if specific genetic mutations contributed to both diseases in our case, but follow-up genetic testing on the recurrent melanoma specimen currently is being pursued.

The 49-year quiescent period in our case of recurrent cutaneous malignant melanoma potentially represents the longest ultra-late recurrence of melanoma in the literature to date based on a review of indexed publications. Moreover, it is relatively unique compared to other similar cases in that the recurrence was within a centimeter of the original excisional scar. Most metastases occur in locoregional lymph nodes or the lungs³; therefore, it is unusual to find one so close to the original lesion, especially one that occurred decades later. Factors associated with ultra-late recurrences are unknown, primarily because of the rarity of these cases as well as the biases and other factors that limit existing studies. However, genetic sequencing may provide information regarding these factors and related processes. Genetic sequencing specifically points to a small cell group remaining after excision of the primary tumor, which mutates while proliferating. Low antigenicity and tolerance to immunity during the quiescent period may explain the long duration of dormancy.⁶ More recently, there have been efforts to identify immunohistochemical signatures that may predict late recurrences, though the data are preliminary in nature.¹¹

Given the latency period and location of the recurrence, our case demonstrates that even fully excised melanomas may recur locally many decades later, hence patients should be aware of the importance of a lifetime of vigilance after being diagnosed with melanoma.

To the Editor:

Ultra-late melanoma recurrence represents a minority of cases in which the quiescent period lasts longer than 15 years, and epidemiologic studies have reported recurrence rates of 6% to 10% during the ultra-late period.¹ Even more uncommon are cases that span many decades (eg, >30 years), but all are useful in understanding the cellular behavior leading to the reactivation of fully excised melanomas. Few cases have been reported in which recurrence occurs more than 35 years after the original diagnosis of melanoma. Unfortunately, mechanisms underlying this long stable quiescence and subsequent reactivation are poorly understood, which is why it is important to identify and document cases. We present a case of local recurrence of cutaneous melanoma on the patient’s lower back after a 49-year disease-free period.

A 78-year-old White woman presented to a private dermatology office for a full-body skin examination. She had a medical history of a cutaneous melanoma that had been removed on the lower back 49 years prior; Parkinson disease of 10 years’ duration; and an enlarged thyroid nodule with decreased thyrotropin and hyperthyroidism, atrial fibrillation, mitral valve prolapse, osteoarthritis in the knees, and actinic keratoses, all of which were chronic conditions lasting years to decades. She was taking several medications for these medical conditions. Her surgical history included a hysterectomy, hip replacement, hernia repair, cardioversion, and tonsillectomy in childhood. Her family medical history included breast cancer in her paternal grandmother and aunt; hypertension in her father; and sarcoma in her mother at 78 years of age, which initially was identified in the sacrum and metastasized to the lungs causing death. No family history of melanoma or other skin cancers was reported. Prior to the original diagnosis of melanoma at 29 years of age, she had no history of skin cancer or any other medical condition other than acne. The patient did report spending a great deal of time in the sun during high school.

The patient reported developing the original cutaneous melanoma during her second pregnancy at 29 years of age and recalled that it was excised with wide margins. There had been a mole on her back that was present for years but changed in size during pregnancy, prompting the original visit to the primary care physician for evaluation. Remarkably, the original pathology report was obtained from the patient and revealed a specimen consisting of a 3.7×1.7-cm skin ellipse averaging 0.7 cm in thickness. In the center of the specimen was a 0.6-cm, round, raised, pigmented lesion that revealed moderately frequent mitoses on microscopic evaluation. It was determined by the pathologist to be a malignant tumor, and the report stated that the surgical margins appeared clear.

Physical examination at the current presentation 49 years later revealed an even-bordered 2-mm black macule that was located approximately 1 cm from the original melanoma excision scar line (Figure). A biopsy was performed and sent to a dermatopathologist. Microscopic evaluation revealed nests, islands, and sheets of atypical epithelioid melanocytes extending through the dermis between collagen bundles. The melanocytes varied in size and shape with moderate nuclear pleomorphism present. Scattered mitotic figures and necrotic melanocytes were present, which most likely represented cutaneous satellite metastases of melanoma. Subsequent chest radiography, full-body positron emission tomography, and standard laboratory blood tests were unremarkable except for an enlarged right thyroid gland and moderate cardiomegaly. The patient was sent to a surgical oncologist for excision with wide surgical margins, and she elected not to have a sentinel lymph node biopsy. At follow-up 3, 6, 12, and 24 months later, there were no signs of recurrence based on direct clinical examination. The patient subsequently was lost to follow-up.

Recurrence rates of melanoma vary by stage and age at diagnosis, but prior studies have reported a recurrence rate of approximately 6% after 10 or more years following the initial diagnosis.² Ultra-late recurrences of approximately 4 decades or more are extremely rare. A PubMed search of articles indexed for MEDLINE using the terms melanoma and ultra-late recurrence revealed 4 reported cases with a quiescent period of 38 or more years.^3-6 All cases were metastatic melanomas in women; spanned 38, 40, 41, and 45 years from the initial melanoma diagnosis to recurrence; and all of the recurrences except one were regional or distal metastatic lesions (eg, lymph node, brain). In one case, both the original and recurrent lesions occurred on the left elbow.⁶ The original lesions occurred on the legs, elbow, and back of the neck, and there were no notable concomitant medical conditions. The patients were aged 72, 73, 73, and 84 years at recurrence.^3-6 However, generalizations from these cases are limited given the potential for selection bias (eg, men may be less likely to visit a clinic for follow-up and nevi examination) and the likelihood that many cases of ultra-late melanoma recurrence are unrecognized or unreported.

More recently, genomic analyses on melanoma lesions occurring 30 years apart confirmed that the second lesion was indeed a recurrence, although with numerous additional mutations.⁷ The specific mechanisms underlying the dormancy and subsequent reemergence of metastatic lesions are unclear, but there may be aberrations in the skin beyond histopathologic margins that represent an early phase of disease that are histologically unrecognizable and may lay dormant for many years before reemerging in response to external or immunologic changes.⁸ Alternatively, recurrences may be associated with lymphatic or hematogenous emboli, or there may be a tendency for melanomas to metastasize to inflamed or scarred tissue representing a tropism of the malignant melanocytes.⁹

It also is worth highlighting the concomitant diagnosis of Parkinson disease in our patient. In recent years, Parkinson disease has been linked to melanoma in both epidemiologic and genetic studies. For example, one large-scale study found a 50% increased risk for developing Parkinson disease in patients with melanoma (and vice versa), and this finding has been replicated in other studies.¹⁰ Moreover, patients with Parkinson disease have a 2-fold increase in their risk for developing melanoma, demonstrating that it is a bidirectional pathway. Not surprisingly, associations between melanin and neuromelanin pathways have been identified as a potential link between these diseases, and scientists are in the process of understanding the genetic components of both.¹⁰ It is unknown if specific genetic mutations contributed to both diseases in our case, but follow-up genetic testing on the recurrent melanoma specimen currently is being pursued.

The 49-year quiescent period in our case of recurrent cutaneous malignant melanoma potentially represents the longest ultra-late recurrence of melanoma in the literature to date based on a review of indexed publications. Moreover, it is relatively unique compared to other similar cases in that the recurrence was within a centimeter of the original excisional scar. Most metastases occur in locoregional lymph nodes or the lungs³; therefore, it is unusual to find one so close to the original lesion, especially one that occurred decades later. Factors associated with ultra-late recurrences are unknown, primarily because of the rarity of these cases as well as the biases and other factors that limit existing studies. However, genetic sequencing may provide information regarding these factors and related processes. Genetic sequencing specifically points to a small cell group remaining after excision of the primary tumor, which mutates while proliferating. Low antigenicity and tolerance to immunity during the quiescent period may explain the long duration of dormancy.⁶ More recently, there have been efforts to identify immunohistochemical signatures that may predict late recurrences, though the data are preliminary in nature.¹¹

Given the latency period and location of the recurrence, our case demonstrates that even fully excised melanomas may recur locally many decades later, hence patients should be aware of the importance of a lifetime of vigilance after being diagnosed with melanoma.

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

Cutaneous Manifestations

Contact dermatitis is a common problem for individuals who work in the floral industry. Hand dermatitis has been reported in as many as 26% of floral employees.¹Tulipa species have been identified as one of the most common causes of hand dermatitis. Tulipalin A (α-methylene-γ-butyrolactone) is the main sensitizer in tulips (Figure 1) and its precursor tuliposide A also occurs both in tulips and the Peruvian lily (Alstroemeria).

In a 1996 study, 18% (9/51) of tulip workers were found to be allergic to tulipalin A.² In a more recent study of 164 tulip workers, 48 (29.3%) had clinical evidence of contact dermatitis and subsequently underwent patch testing; 17 (35.4%) showed a positive reaction to either tulipalin A or to tulip-bulb extract.³ Itching was the most common symptom (39 workers [81.3%]) and hand eczema at the tip of the thumb and index finger was the most common finding. In 9 (18.8%) workers, eczema had spread to other body parts including the forearm, face, legs, and abdomen.³

Peruvian lily is widely used in floral arrangements and has become a leading cause of hand dermatitis in florists (Figure 2). Large amounts of free tulipalin A are present in bulb scales of tulips, along with a small amount of tuliposide A. In young developing shoots, the situation is reversed: Both compounds are found in all parts of the plant to some degree, though tulipalin A is the major allergen, and more mature parts of the plant and bulb are most allergenic.

Cultural Considerations

In traditional Kurdish cuisine, raw herbs are part of snacking or are served as a side dish (sawza). Snacks often are consumed raw on the spot. Tulipa montana, Tulipa armena, and possibly other Tulipa species are consumed as a snack.⁴ Traditionally, Tulipa systola is consumed by the Kurds as an anti-inflammatory medicine and for pain relief. It also has been proposed that T systola has antioxidant properties.⁵ Cooked tulip also has been consumed in time of famine in Europe, though none of these dietary practices are recommended.⁴

Clinical Presentation

“Tulip fingers” describes the most common presentation of contact dermatitis caused by tulip bulbs. Erythematous scaling plaques are seen in the periungual skin and first and second fingertips of the dominant hand. Other manifestations include diffuse dry dermatitis of the hand; paronychia; pulpitis; and secondary spread to the face, neck, arms, and genitalia, with eczematous papules and plaques.⁶ Clinical signs include erythema, vesicles, hyperkeratosis, and exfoliation of the fingertips. The allergen also can cause airborne contact dermatitis and manifest as conjunctivitis, rhinitis, and asthma.² A considerable number of tulip workers develop paresthesia and tenderness in the fingertips within several hours after working with tulip bulbs, known as “tulip fire.”⁷

Plant Facts

There are approximately 250 genera of bulbous plants. Tulips are members of the genus Tulipa and family Liliaceae. Tulips often are thought of as native to southwest central Asia and Turkey⁸; however, Tulipa sylvestris is native to Portugal, Spain, and North Africa.

Etymology and Symbolism—The word tulip is derived from the Turkish word türbent meaning a turban, possibly because the flower is compared to turbans worn by men of the Ottoman Empire in the 16th century. In Turkish culture, the tulip is a symbol of paradise on earth and can have divine status. In the Netherlands, on the other hand, the tulip represents the briefness of life.

History—By 1562, tulip bulbs had already been introduced to Holland by merchants. However, the first shipment of tulip bulbs was mistaken by the Dutch for onions and were either roasted over a fire or perished when planted in gardens with vegetables. Carolus Clusius—botanist, director of the imperial medical garden in Vienna and recipient of many plants through diplomatic channels—was particularly fond of flower bulbs and contributed to the popularity of the tulip in Europe by sending bulbs and seeds to other European countries.

In the early 17th century, the tulip craze began in France, fueled by a viral disease of tulips that produced variegated color patterns on the petals; entire properties were sold in exchange for a single tulip bulb. The tulip craze drifted from France to Holland in 1634 for 3 years before the tulip market collapsed.

More recently, in 2003 investors started a multimillion-euro tulip fund in the Netherlands to develop new varieties of tulip. Tulip bulbs were used to create money with high percentages over the selling price. With exorbitant pricing and ever-changing ownership of bulbs—bulbs were bought and sold as many as 10 times—the tulip fund collapsed 1 year later and investors lost their money. Bulb speculators then took their profit abroad. In 2006, bulb owners were charged with fraud; the tulip craze often is cited as one of the early major stock market collapses.

Tulips continue to grow in popularity. Today, nearly 6000 cultivars are registered, with 40 new cultivars registered every 5 years.⁹

Identifying Features

At the base of the erect tulip plant is a cluster of 2 or 3 thick bluish-green leaves. Three petals and 3 sepals make up the solitary bell-shaped flower. Many tulips can propagate only by means of their scaly bulbs. The flowers arise from the tips of stems in different solid colors, except true blue—from pure white to all shades of yellow, red, and a deep purple that is almost black. Solid-color tulips are called “self-colored.” So-called broken tulips are individual flowers with multiple colors, a condition caused by a viral disease transmitted by aphids.¹⁰

Tulip Allergen

Tuliposide A is found in many species of the genera Tulipa, Alstroemeria, and Erythronium.⁶ So far, 7 analogs have been identified: 1-tuliposide A and B; 6-tuliposide A and B; and tuliposides D, E, and F. 6-Tuliposide A and B are the principal tuliposides found in tulip cultivars.¹¹ With trauma and maturation, tuliposides A and B are hydrolyzed to tulipalin A and tulipalin B, respectively.

Tulipalin A and tulipalin B have antimicrobial properties against bacteria and fungi; tulipalin A is mostly an antifungal agent, and tulipalin B has mostly bacteriostatic characteristics.¹² The highest concentration of tulipalin A is found in the outer layer of the bulb, followed by (in descending order) the stem, leaves, and petals.¹³

The prevalence of tulipalin A allergy led the German Federal Institute for Risk Assessment to assign tuliposide A and tulipalin A to category B, which is a “solid-based indication for contact allergenic effects”; both chemicals also are considered skin sensitizers, defined by the Globally Harmonized System of Classification and Labelling of Chemicals of the United Nations as a substance that will induce an allergic response following skin contact.¹⁴ Patients who are allergic to tulips have cross-sensitivity to Alstroemeria because tuliposide A and its metabolites are found in both plants.¹⁵

Symptoms of an allergic response to tulipalin A can be immediate or delayed.¹⁴ The most common allergic contact dermatitis caused by tulip bulbs is type IV hypersensitivity, though type I reactions can occur. Symptoms of a type I reaction including contact urticaria, rhinitis, hoarseness, and dyspnea have been reported.¹⁴

The variety of tulip handled also contributes to the severity of dermatitis. Handling bulbs of Rose Copeland variety tulips and cutting the flowers of Preludium tulips have been associated with more severe allergic dermatitis presentations, whereas the Red Emperor tulip was found to have less tuliposide A and thus provoke a weaker patch-test reaction.⁷

A Word About Garlic—Garlic is in the subfamily Allioideae (formerly Alliaceae) taxonomically related to the tulip family (Liliaceae). Garlic also can cause hand dermatitis in cooks, with a similar clinical appearance as tulip fingers. Gas chromatography has shown that garlic contains predominantly tuliposide B, which has been found to be much less allergenic than tuliposide A.^7,16

Prevention of Tulipa Dermatitis

Tuliposide A and its metabolites can be found in storehouses and trucks used to transport tulips, in clothing, and in any other place where dust containing the allergen has settled. The best prevention against contact dermatitis is to avoid the inciting plants. Gloves may prevent contact dermatitis due to tuliposide A, which penetrates vinyl but not nitrile gloves. Barrier creams have been proposed, but data are scant.¹

Occupational sun exposure is a well-known risk factor for the development of melanoma and nonmelanoma skin cancer (NMSC). In addition to sun exposure, US military personnel may face other risk factors such as lack of access to adequate sun protection, work in equatorial latitudes, and increased exposure to carcinogens. In one study, fewer than 30% of surveyed soldiers reported regular sunscreen use during deployment and reported the face, neck, and upper extremities were unprotected at least 70% of the time.¹ Skin cancer risk factors that are more common in military service members include inadequate sunscreen access, insufficient sun protection, harsh weather conditions, more immediate safety concerns than sun protection, and male gender. A higher incidence of melanoma and NMSC has been correlated with the more common demographics of US veterans such as male sex, older age, and White race.²

Although not uncommon in both civilian and military populations, we present the case of a military service member who developed skin cancer at an early age potentially due to occupational sun exposure. We also provide a review of the literature to examine the risk factors and incidence of melanoma and NMSC in US military personnel and veterans and provide recommendations for skin cancer prevention, screening, and intervention in the military population.

Case Report

A 37-year-old White active-duty male service member in the US Navy (USN) presented with a nonhealing lesion on the nose of 2 years’ duration that had been gradually growing and bleeding for several weeks. He participated in several sea deployments while onboard a naval destroyer over his 10-year military career. He did not routinely use sunscreen during his deployments. His personal and family medical history lacked risk factors for skin cancer other than his skin tone and frequent sun exposure.

Physical examination revealed a 1-cm ulcerated plaque with rolled borders and prominent telangiectases on the mid nasal dorsum. A shave biopsy was performed to confirm the diagnosis of nodular basal cell carcinoma (BCC). The patient underwent Mohs micrographic surgery, which required repair with an advancement flap. He currently continues his active-duty service and is preparing for his next overseas deployment.

Literature Review

We conducted a review of PubMed articles indexed for MEDLINE using the search terms skin cancer, melanoma, nonmelanoma skin cancer, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, Merkel cell carcinoma, dermatofibrosarcoma protuberans, or sebaceous carcinoma along with military, Army, Navy, Air Force, or veterans. Studies from January 1984 to April 2020 were included in our qualitative review. All articles were reviewed, and those that did not examine skin cancer and the military population in the United States were excluded. Relevant data, such as results of skin cancer incidence or risk factors or insights about developing skin cancer in this affected population, were extracted from the selected publications.

Several studies showed overall increased age-adjusted incidence rates of melanoma and NMSC among military service personnel compared to age-matched controls in the general population.² A survey of draft-age men during World War II found a slightly higher percentage of respondents with history of melanoma compared to the control group (83% [74/89] vs 76% [49/65]). Of those who had a history of melanoma, 34% (30/89) served in the tropics compared to 6% (4/65) in the control group.³ A tumor registry review found the age-adjusted melanoma incidence rates per 100,000 person-years for White individuals in the military vs the general population was 33.6 vs 27.5 among those aged 45 to 49 years, 49.8 vs 32.2 among those aged 50 to 54 years, and 178.5 vs 39.2 among those aged 55 to 59 years.⁴ Among published literature reviews, members of the US Air Force (USAF) had the highest rates of melanoma compared to other military branches, with an incidence rate of 7.6 vs 6.3 among USAF males vs Army males and 9.0 vs 5.5 among USAF females vs Army females.⁴ These findings were further supported by another study showing a higher incidence rate of melanoma in USAF members compared to Army personnel (17.8 vs 9.5) and a 62% greater melanoma incidence in active-duty military personnel compared to the general population when adjusted for age, race, sex, and year of diagnosis.⁵ Additionally, a meta-analysis reported a standardized incidence ratio of 1.4 (95% CI, 1.1-1.9) for malignant melanoma and 1.8 (95% CI, 1.3-2.8) for NMSC among military pilots compared to the general population.⁶ It is important to note that these data are limited to published peer-reviewed studies within PubMed and may not reflect the true skin cancer incidence.

More comprehensive studies are needed to compare NMSC incidence rates in nonpilot military populations compared to the general population. From 2005 to 2014, the average annual NMSC incidence rate in the USAF was 64.4 per 100,000 person-years, with the highest rate at 97.4 per 100,000 person-years in 2007.⁷ However, this study did not directly compare military service members to the general population. Service in tropical environments among World War II veterans was associated with an increased risk for NMSC. Sixty-six percent of patients with BCC (n=197) and 68% with squamous cell carcinoma (SCC)(n=41) were stationed in the Pacific, despite the number and demographics of soldiers deployed to the Pacific and Europe being approximately equal.⁸ During a 6-month period in 2008, a Combat Dermatology Clinic in Iraq showed 5% (n=129) of visits were for treatment of actinic keratoses (AKs), while 8% of visits (n=205) were related to skin cancer, including BCC, SCC, mycosis fungoides, and melanoma.⁹ Overall, these studies confirm a higher rate of melanoma in military service members vs the general population and indicate USAF members may be at the greatest risk for developing melanoma and NMSC among the service branches. Further studies are needed to elucidate why this might be the case and should concentrate on demographics, service locations, uniform wear and personal protective equipment standards, and use of sun-protective measures across each service branch.

Our search yielded no aggregate studies to determine if there is an increased rate of other types of skin cancer in military service members such as Merkel cell carcinoma, dermatofibrosarcoma protuberans, and microcystic adnexal carcinoma (MAC). Gerall et al¹⁰ described a case of MAC in a 43-year-old USAF U-2 pilot with a 15-year history of a slow-growing soft-tissue nodule on the cheek. The patient’s young age differed from the typical age of MAC occurrence (ie, 60–70 years), which led to the possibility that his profession contributed to the development of MAC and the relatively young age of onset.¹⁰

Etiology of Disease

The results of our literature review indicated that skin cancers are more prevalent among active-duty military personnel and veterans than in the general population; they also suggest that frequent sun exposure and lack of sun protection may be key etiologic factors. In 2015, only 23% of veterans (n=49) reported receiving skin cancer awareness education from the US Military.¹ Among soldiers returning from Iraq and Afghanistan (n=212), only 13% reported routine sunscreen use, and less than 30% reported having routine access to sunscreen while working more than 4 hours per day in direct sunlight or 75% of the day working in direct sunlight. Of these, the majority reported sustaining at least 1 sunburn, while 43% had at least 2 sunburns and 20% reported a history of a blistering sunburn during deployment.¹ The intermittent exposure hypothesis—defined as the theory that intense periods of exposure to UV radiation increase the risk for melanoma more than chronic cumulative UV radiation exposure—may explain how occupational exposure in the military may lead to increased skin cancer incidence. Individuals exposed to brief periods of intense, inconsistent, or unpredictable UV radiation may lack protective adaptive mechanisms compared to those who are chronically exposed.²

Exposure to UV radiation at higher altitudes (with corresponding higher UV energy) and altered sleep-wake cycles (with resulting altered immune defenses) may contribute to higher rates of melanoma and NMSC among USAF pilots.¹¹ During a 57-minute flight at 30,000-ft altitude, a pilot is exposed to a UVA dose equivalent to 20 minutes inside a tanning booth.¹² Although UVB transmission through plastic and glass windshields was reported to be less than 1%, UVA transmission ranged from 0.4% to 53.5%. The UVA dose for a pilot flying a light aircraft in Las Vegas, Nevada, was reported to be 127 μW/cm² at ground level vs 242 μW/cm² at a 30,000-ft altitude.¹² Therefore, cosmic radiation exposure for military pilots is higher than for commercial pilots, as they fly at higher altitudes. U-2 pilots are exposed to 20 times the cosmic radiation dose at sea level and 10 times the exposure of commercial pilots.¹⁰

It currently is unknown why service in the USAF would increase skin cancer risk compared to service in other branches; however, there are some differences between military branches that require further research, including ethnic demographics, uniform wear and personal protective equipment standards, duty assignment locations, and the hours the military members are asked to work outside with direct sunlight exposure for each branch of service. Environmental exposures may differ based on the military branch gear requirements; for example, when on the flight line or flight deck, USN aircrews are required to wear cranials (helmets), eyewear (visor or goggles), and long-sleeved shirts. When at sea, USN flight crews wear gloves, headgear, goggles, pants, and long-sleeved shirts to identify their duty onboard. All of these measures offer good sun protection and are carried over to the land-based flight lines in the USN and Marine Corps. Neither the Army nor the USAF commonly utilize these practices. Conversely, the USAF does not allow flight line workers including fuelers, maintainers, and aircrew to wear coveralls due to the risk of being blown off, becoming foreign object debris, and being sucked into jet engines. However, in-flight protective gear such as goggles, gloves, and coveralls are worn.¹² Perhaps the USAF may attract, recruit, or commission people with inherently more risk for skin cancer (eg, White individuals). How racial and ethnic factors may affect skin cancer incidence in military branches is an area for future research efforts.

Recommendations

Given the considerable increase in risk factors, efforts are needed to reduce the disparity in skin cancer rates between US military personnel and their civilian counterparts through appropriate prevention, screening, and intervention programs.

Prevention—In wartime settings as well as in training and other peacetime activities, active-duty military members cannot avoid harmful midday sun exposure. Additionally, application and reapplication of sunscreen can be challenging. Sunscreen, broad-spectrum lip balm, and wide-brimmed “boonie” hats can be ordered by supply personnel.¹³ We recommend that a standard sunscreen supply be available to all active-duty military service members. The long-sleeved, tightly woven fabric of military uniforms also can provide protection from the sun but can be difficult to tolerate for extended periods of time in warm climates. Breathable, lightweight, sun-protective clothing is commercially available and could be incorporated into military uniforms.

All service members should be educated about skin cancer risks while addressing common myths and inaccuracies. Fifty percent (n=50) of surveyed veterans thought discussions of skin cancer prevention and safety during basic training could help prevent skin cancer in service members.¹⁴ Suggestions from respondents included education about sun exposure consequences, use of graphic images of skin cancer in teaching, providing protective clothing and sunscreen to active-duty military service members, and discussion about sun protection with physicians during annual physicals. When veterans with a history of skin cancer were surveyed about their personal risk for skin cancer, most believed they were at little risk (average perceived risk response score, 2.2 out of 5 [1=no risk; 5=high risk]).¹⁴ The majority explained that they did not seek sun protection after warnings of skin cancer risk because they did not think skin cancer would happen to them,¹⁴ though the incidence of NMSC in the United States at the time of these surveys was estimated to be 3.5 million per year.^14,15 Another study found that only 13% of veterans knew the back is the most common site of melanoma in men.¹ The Army Public Health Center has informational fact sheets available online or in dermatologists’ offices that detail correct sunscreen application techniques and how to reduce sun exposure.^16,17 However, military service members reported that they prefer physicians to communicate with them directly about skin cancer risks vs reading brochures in physician offices or gaining information from television, radio, military training, or the Internet (4.4 out 5 rating for communication methods of risks associated with skin cancer [1=ineffective; 5=very effective]).¹⁴ However, only 27% of nondermatologist physicians counseled or screened their patients on skin cancer or sunscreen yearly, 49% even less frequently, with 24% never counseling or screening at all. Because not all service members may be able to regularly see a dermatologist, efforts should be focused on increasing primary care physician awareness on counseling and screening.¹⁸

Early Detection—Military service members should be educated on how to perform skin self-examinations to alert their providers earlier to concerning lesions. The American Academy of Dermatology publishes infographics regarding the ABCDEs of melanoma and how to perform skin self-examinations.^19,20 Although the US Preventive Services Task Force concluded there was insufficient evidence to recommend skin self-examination for all adults, the increased risk that military service members and veterans have requires further studies to examine the utility of self-screening in this population.²⁰ Given the evidence of a higher incidence of melanoma in military service members vs the general population after 45 years of age,⁴ we recommend starting yearly in-person screenings performed by primary care physicians or dermatologists at this age. Ensuring every service member has routine in-office skin examinations can be difficult given the limited number of active-duty military dermatologists. Civilian dermatologists also could be helpful in this respect.

Teleconsultation, teledermoscopy, or store-and-forward imaging services for concerning lesions could be utilized when in-person consultations with a dermatologist are not feasible or cannot be performed in a timely manner. From 2004 to 2012, 40% of 10,817 teleconsultations were dermatology consultations from deployed or remote environments.²¹ Teleconsultation can be performed via email through the global military teleconsultation portal.²² These methods can lead to earlier detection of skin cancer rather than delaying evaluation for an in-person consultation.²³

Intervention—High-risk patients who have been diagnosed with NMSC or many AKs should consider oral, procedural, or topical chemoprevention to reduce the risk for additional skin cancers as both primary and secondary prevention. In a double-blind, randomized, controlled trial of 386 individuals with a history of 2 or more NMSCs, participants were randomly assigned to receive either 500 mg of nicotinamide twice daily or placebo for 12 months. Compared to the placebo group, the nicotinamide group had a 23% lower rate of new NMSCs and an 11% lower rate of new AKs at 12 months.²⁴ The use of acitretin also has been studied in transplant recipients for the chemoprevention of NMSC. In a double-blind, randomized, controlled trial of renal transplant recipients with more than 10 AKs randomized to receive either 30 mg/d of acitretin or placebo for 6 months, 11% of the acitretin group reported a new NMSC compared to 47% in the placebo group.²⁵ An open-label study of 27 renal transplant recipients treated with methyl-esterified aminolevulinic acid–photodynamic therapy and red light demonstrated an increased mean time to occurrence of an AK, SCC, BCC, keratoacanthoma, or wart from 6.8 months in untreated areas compared to 9.6 months in treated areas.²⁵ In active-duty locations where access to red and blue light sources is unavailable, the use of daylight photodynamic therapy can be considered, as it does not require any special equipment. Topical treatments such as 5-fluorouracil and imiquimod can be used for treatment and chemoprevention of NMSC. In a follow-up study from the Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial, patients who applied 5-fluorouracil cream 5% twice daily to the face and ears for 4 weeks had a 75% risk reduction in developing SCC requiring surgery compared to the control group for the first year after treatment.^26,27

Final Thoughts

Focusing on the efforts we propose can help the US Military expand their prevention, screening, and intervention programs for skin cancer in service members. Further research can then be performed to determine which programs have the greatest impact on rates of skin cancer among military and veteran personnel. Given these higher incidences and risk of exposure for skin cancer among service members, the various services may consider mandating sunscreen use as part of the uniform to prevent skin cancer. To maximize effectiveness, these efforts to prevent the development of skin cancer among military and veteran personnel should be adopted nationally.

Occupational sun exposure is a well-known risk factor for the development of melanoma and nonmelanoma skin cancer (NMSC). In addition to sun exposure, US military personnel may face other risk factors such as lack of access to adequate sun protection, work in equatorial latitudes, and increased exposure to carcinogens. In one study, fewer than 30% of surveyed soldiers reported regular sunscreen use during deployment and reported the face, neck, and upper extremities were unprotected at least 70% of the time.¹ Skin cancer risk factors that are more common in military service members include inadequate sunscreen access, insufficient sun protection, harsh weather conditions, more immediate safety concerns than sun protection, and male gender. A higher incidence of melanoma and NMSC has been correlated with the more common demographics of US veterans such as male sex, older age, and White race.²

Although not uncommon in both civilian and military populations, we present the case of a military service member who developed skin cancer at an early age potentially due to occupational sun exposure. We also provide a review of the literature to examine the risk factors and incidence of melanoma and NMSC in US military personnel and veterans and provide recommendations for skin cancer prevention, screening, and intervention in the military population.

Case Report

A 37-year-old White active-duty male service member in the US Navy (USN) presented with a nonhealing lesion on the nose of 2 years’ duration that had been gradually growing and bleeding for several weeks. He participated in several sea deployments while onboard a naval destroyer over his 10-year military career. He did not routinely use sunscreen during his deployments. His personal and family medical history lacked risk factors for skin cancer other than his skin tone and frequent sun exposure.

Physical examination revealed a 1-cm ulcerated plaque with rolled borders and prominent telangiectases on the mid nasal dorsum. A shave biopsy was performed to confirm the diagnosis of nodular basal cell carcinoma (BCC). The patient underwent Mohs micrographic surgery, which required repair with an advancement flap. He currently continues his active-duty service and is preparing for his next overseas deployment.

Literature Review

We conducted a review of PubMed articles indexed for MEDLINE using the search terms skin cancer, melanoma, nonmelanoma skin cancer, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, Merkel cell carcinoma, dermatofibrosarcoma protuberans, or sebaceous carcinoma along with military, Army, Navy, Air Force, or veterans. Studies from January 1984 to April 2020 were included in our qualitative review. All articles were reviewed, and those that did not examine skin cancer and the military population in the United States were excluded. Relevant data, such as results of skin cancer incidence or risk factors or insights about developing skin cancer in this affected population, were extracted from the selected publications.

Several studies showed overall increased age-adjusted incidence rates of melanoma and NMSC among military service personnel compared to age-matched controls in the general population.² A survey of draft-age men during World War II found a slightly higher percentage of respondents with history of melanoma compared to the control group (83% [74/89] vs 76% [49/65]). Of those who had a history of melanoma, 34% (30/89) served in the tropics compared to 6% (4/65) in the control group.³ A tumor registry review found the age-adjusted melanoma incidence rates per 100,000 person-years for White individuals in the military vs the general population was 33.6 vs 27.5 among those aged 45 to 49 years, 49.8 vs 32.2 among those aged 50 to 54 years, and 178.5 vs 39.2 among those aged 55 to 59 years.⁴ Among published literature reviews, members of the US Air Force (USAF) had the highest rates of melanoma compared to other military branches, with an incidence rate of 7.6 vs 6.3 among USAF males vs Army males and 9.0 vs 5.5 among USAF females vs Army females.⁴ These findings were further supported by another study showing a higher incidence rate of melanoma in USAF members compared to Army personnel (17.8 vs 9.5) and a 62% greater melanoma incidence in active-duty military personnel compared to the general population when adjusted for age, race, sex, and year of diagnosis.⁵ Additionally, a meta-analysis reported a standardized incidence ratio of 1.4 (95% CI, 1.1-1.9) for malignant melanoma and 1.8 (95% CI, 1.3-2.8) for NMSC among military pilots compared to the general population.⁶ It is important to note that these data are limited to published peer-reviewed studies within PubMed and may not reflect the true skin cancer incidence.

More comprehensive studies are needed to compare NMSC incidence rates in nonpilot military populations compared to the general population. From 2005 to 2014, the average annual NMSC incidence rate in the USAF was 64.4 per 100,000 person-years, with the highest rate at 97.4 per 100,000 person-years in 2007.⁷ However, this study did not directly compare military service members to the general population. Service in tropical environments among World War II veterans was associated with an increased risk for NMSC. Sixty-six percent of patients with BCC (n=197) and 68% with squamous cell carcinoma (SCC)(n=41) were stationed in the Pacific, despite the number and demographics of soldiers deployed to the Pacific and Europe being approximately equal.⁸ During a 6-month period in 2008, a Combat Dermatology Clinic in Iraq showed 5% (n=129) of visits were for treatment of actinic keratoses (AKs), while 8% of visits (n=205) were related to skin cancer, including BCC, SCC, mycosis fungoides, and melanoma.⁹ Overall, these studies confirm a higher rate of melanoma in military service members vs the general population and indicate USAF members may be at the greatest risk for developing melanoma and NMSC among the service branches. Further studies are needed to elucidate why this might be the case and should concentrate on demographics, service locations, uniform wear and personal protective equipment standards, and use of sun-protective measures across each service branch.

Our search yielded no aggregate studies to determine if there is an increased rate of other types of skin cancer in military service members such as Merkel cell carcinoma, dermatofibrosarcoma protuberans, and microcystic adnexal carcinoma (MAC). Gerall et al¹⁰ described a case of MAC in a 43-year-old USAF U-2 pilot with a 15-year history of a slow-growing soft-tissue nodule on the cheek. The patient’s young age differed from the typical age of MAC occurrence (ie, 60–70 years), which led to the possibility that his profession contributed to the development of MAC and the relatively young age of onset.¹⁰

Etiology of Disease

The results of our literature review indicated that skin cancers are more prevalent among active-duty military personnel and veterans than in the general population; they also suggest that frequent sun exposure and lack of sun protection may be key etiologic factors. In 2015, only 23% of veterans (n=49) reported receiving skin cancer awareness education from the US Military.¹ Among soldiers returning from Iraq and Afghanistan (n=212), only 13% reported routine sunscreen use, and less than 30% reported having routine access to sunscreen while working more than 4 hours per day in direct sunlight or 75% of the day working in direct sunlight. Of these, the majority reported sustaining at least 1 sunburn, while 43% had at least 2 sunburns and 20% reported a history of a blistering sunburn during deployment.¹ The intermittent exposure hypothesis—defined as the theory that intense periods of exposure to UV radiation increase the risk for melanoma more than chronic cumulative UV radiation exposure—may explain how occupational exposure in the military may lead to increased skin cancer incidence. Individuals exposed to brief periods of intense, inconsistent, or unpredictable UV radiation may lack protective adaptive mechanisms compared to those who are chronically exposed.²

Exposure to UV radiation at higher altitudes (with corresponding higher UV energy) and altered sleep-wake cycles (with resulting altered immune defenses) may contribute to higher rates of melanoma and NMSC among USAF pilots.¹¹ During a 57-minute flight at 30,000-ft altitude, a pilot is exposed to a UVA dose equivalent to 20 minutes inside a tanning booth.¹² Although UVB transmission through plastic and glass windshields was reported to be less than 1%, UVA transmission ranged from 0.4% to 53.5%. The UVA dose for a pilot flying a light aircraft in Las Vegas, Nevada, was reported to be 127 μW/cm² at ground level vs 242 μW/cm² at a 30,000-ft altitude.¹² Therefore, cosmic radiation exposure for military pilots is higher than for commercial pilots, as they fly at higher altitudes. U-2 pilots are exposed to 20 times the cosmic radiation dose at sea level and 10 times the exposure of commercial pilots.¹⁰

It currently is unknown why service in the USAF would increase skin cancer risk compared to service in other branches; however, there are some differences between military branches that require further research, including ethnic demographics, uniform wear and personal protective equipment standards, duty assignment locations, and the hours the military members are asked to work outside with direct sunlight exposure for each branch of service. Environmental exposures may differ based on the military branch gear requirements; for example, when on the flight line or flight deck, USN aircrews are required to wear cranials (helmets), eyewear (visor or goggles), and long-sleeved shirts. When at sea, USN flight crews wear gloves, headgear, goggles, pants, and long-sleeved shirts to identify their duty onboard. All of these measures offer good sun protection and are carried over to the land-based flight lines in the USN and Marine Corps. Neither the Army nor the USAF commonly utilize these practices. Conversely, the USAF does not allow flight line workers including fuelers, maintainers, and aircrew to wear coveralls due to the risk of being blown off, becoming foreign object debris, and being sucked into jet engines. However, in-flight protective gear such as goggles, gloves, and coveralls are worn.¹² Perhaps the USAF may attract, recruit, or commission people with inherently more risk for skin cancer (eg, White individuals). How racial and ethnic factors may affect skin cancer incidence in military branches is an area for future research efforts.

Recommendations

Given the considerable increase in risk factors, efforts are needed to reduce the disparity in skin cancer rates between US military personnel and their civilian counterparts through appropriate prevention, screening, and intervention programs.

Prevention—In wartime settings as well as in training and other peacetime activities, active-duty military members cannot avoid harmful midday sun exposure. Additionally, application and reapplication of sunscreen can be challenging. Sunscreen, broad-spectrum lip balm, and wide-brimmed “boonie” hats can be ordered by supply personnel.¹³ We recommend that a standard sunscreen supply be available to all active-duty military service members. The long-sleeved, tightly woven fabric of military uniforms also can provide protection from the sun but can be difficult to tolerate for extended periods of time in warm climates. Breathable, lightweight, sun-protective clothing is commercially available and could be incorporated into military uniforms.

All service members should be educated about skin cancer risks while addressing common myths and inaccuracies. Fifty percent (n=50) of surveyed veterans thought discussions of skin cancer prevention and safety during basic training could help prevent skin cancer in service members.¹⁴ Suggestions from respondents included education about sun exposure consequences, use of graphic images of skin cancer in teaching, providing protective clothing and sunscreen to active-duty military service members, and discussion about sun protection with physicians during annual physicals. When veterans with a history of skin cancer were surveyed about their personal risk for skin cancer, most believed they were at little risk (average perceived risk response score, 2.2 out of 5 [1=no risk; 5=high risk]).¹⁴ The majority explained that they did not seek sun protection after warnings of skin cancer risk because they did not think skin cancer would happen to them,¹⁴ though the incidence of NMSC in the United States at the time of these surveys was estimated to be 3.5 million per year.^14,15 Another study found that only 13% of veterans knew the back is the most common site of melanoma in men.¹ The Army Public Health Center has informational fact sheets available online or in dermatologists’ offices that detail correct sunscreen application techniques and how to reduce sun exposure.^16,17 However, military service members reported that they prefer physicians to communicate with them directly about skin cancer risks vs reading brochures in physician offices or gaining information from television, radio, military training, or the Internet (4.4 out 5 rating for communication methods of risks associated with skin cancer [1=ineffective; 5=very effective]).¹⁴ However, only 27% of nondermatologist physicians counseled or screened their patients on skin cancer or sunscreen yearly, 49% even less frequently, with 24% never counseling or screening at all. Because not all service members may be able to regularly see a dermatologist, efforts should be focused on increasing primary care physician awareness on counseling and screening.¹⁸

Early Detection—Military service members should be educated on how to perform skin self-examinations to alert their providers earlier to concerning lesions. The American Academy of Dermatology publishes infographics regarding the ABCDEs of melanoma and how to perform skin self-examinations.^19,20 Although the US Preventive Services Task Force concluded there was insufficient evidence to recommend skin self-examination for all adults, the increased risk that military service members and veterans have requires further studies to examine the utility of self-screening in this population.²⁰ Given the evidence of a higher incidence of melanoma in military service members vs the general population after 45 years of age,⁴ we recommend starting yearly in-person screenings performed by primary care physicians or dermatologists at this age. Ensuring every service member has routine in-office skin examinations can be difficult given the limited number of active-duty military dermatologists. Civilian dermatologists also could be helpful in this respect.

Teleconsultation, teledermoscopy, or store-and-forward imaging services for concerning lesions could be utilized when in-person consultations with a dermatologist are not feasible or cannot be performed in a timely manner. From 2004 to 2012, 40% of 10,817 teleconsultations were dermatology consultations from deployed or remote environments.²¹ Teleconsultation can be performed via email through the global military teleconsultation portal.²² These methods can lead to earlier detection of skin cancer rather than delaying evaluation for an in-person consultation.²³

Intervention—High-risk patients who have been diagnosed with NMSC or many AKs should consider oral, procedural, or topical chemoprevention to reduce the risk for additional skin cancers as both primary and secondary prevention. In a double-blind, randomized, controlled trial of 386 individuals with a history of 2 or more NMSCs, participants were randomly assigned to receive either 500 mg of nicotinamide twice daily or placebo for 12 months. Compared to the placebo group, the nicotinamide group had a 23% lower rate of new NMSCs and an 11% lower rate of new AKs at 12 months.²⁴ The use of acitretin also has been studied in transplant recipients for the chemoprevention of NMSC. In a double-blind, randomized, controlled trial of renal transplant recipients with more than 10 AKs randomized to receive either 30 mg/d of acitretin or placebo for 6 months, 11% of the acitretin group reported a new NMSC compared to 47% in the placebo group.²⁵ An open-label study of 27 renal transplant recipients treated with methyl-esterified aminolevulinic acid–photodynamic therapy and red light demonstrated an increased mean time to occurrence of an AK, SCC, BCC, keratoacanthoma, or wart from 6.8 months in untreated areas compared to 9.6 months in treated areas.²⁵ In active-duty locations where access to red and blue light sources is unavailable, the use of daylight photodynamic therapy can be considered, as it does not require any special equipment. Topical treatments such as 5-fluorouracil and imiquimod can be used for treatment and chemoprevention of NMSC. In a follow-up study from the Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial, patients who applied 5-fluorouracil cream 5% twice daily to the face and ears for 4 weeks had a 75% risk reduction in developing SCC requiring surgery compared to the control group for the first year after treatment.^26,27

Final Thoughts

Focusing on the efforts we propose can help the US Military expand their prevention, screening, and intervention programs for skin cancer in service members. Further research can then be performed to determine which programs have the greatest impact on rates of skin cancer among military and veteran personnel. Given these higher incidences and risk of exposure for skin cancer among service members, the various services may consider mandating sunscreen use as part of the uniform to prevent skin cancer. To maximize effectiveness, these efforts to prevent the development of skin cancer among military and veteran personnel should be adopted nationally.

Occupational sun exposure is a well-known risk factor for the development of melanoma and nonmelanoma skin cancer (NMSC). In addition to sun exposure, US military personnel may face other risk factors such as lack of access to adequate sun protection, work in equatorial latitudes, and increased exposure to carcinogens. In one study, fewer than 30% of surveyed soldiers reported regular sunscreen use during deployment and reported the face, neck, and upper extremities were unprotected at least 70% of the time.¹ Skin cancer risk factors that are more common in military service members include inadequate sunscreen access, insufficient sun protection, harsh weather conditions, more immediate safety concerns than sun protection, and male gender. A higher incidence of melanoma and NMSC has been correlated with the more common demographics of US veterans such as male sex, older age, and White race.²

Although not uncommon in both civilian and military populations, we present the case of a military service member who developed skin cancer at an early age potentially due to occupational sun exposure. We also provide a review of the literature to examine the risk factors and incidence of melanoma and NMSC in US military personnel and veterans and provide recommendations for skin cancer prevention, screening, and intervention in the military population.

Case Report

A 37-year-old White active-duty male service member in the US Navy (USN) presented with a nonhealing lesion on the nose of 2 years’ duration that had been gradually growing and bleeding for several weeks. He participated in several sea deployments while onboard a naval destroyer over his 10-year military career. He did not routinely use sunscreen during his deployments. His personal and family medical history lacked risk factors for skin cancer other than his skin tone and frequent sun exposure.

Physical examination revealed a 1-cm ulcerated plaque with rolled borders and prominent telangiectases on the mid nasal dorsum. A shave biopsy was performed to confirm the diagnosis of nodular basal cell carcinoma (BCC). The patient underwent Mohs micrographic surgery, which required repair with an advancement flap. He currently continues his active-duty service and is preparing for his next overseas deployment.

Literature Review

We conducted a review of PubMed articles indexed for MEDLINE using the search terms skin cancer, melanoma, nonmelanoma skin cancer, basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, Merkel cell carcinoma, dermatofibrosarcoma protuberans, or sebaceous carcinoma along with military, Army, Navy, Air Force, or veterans. Studies from January 1984 to April 2020 were included in our qualitative review. All articles were reviewed, and those that did not examine skin cancer and the military population in the United States were excluded. Relevant data, such as results of skin cancer incidence or risk factors or insights about developing skin cancer in this affected population, were extracted from the selected publications.

Several studies showed overall increased age-adjusted incidence rates of melanoma and NMSC among military service personnel compared to age-matched controls in the general population.² A survey of draft-age men during World War II found a slightly higher percentage of respondents with history of melanoma compared to the control group (83% [74/89] vs 76% [49/65]). Of those who had a history of melanoma, 34% (30/89) served in the tropics compared to 6% (4/65) in the control group.³ A tumor registry review found the age-adjusted melanoma incidence rates per 100,000 person-years for White individuals in the military vs the general population was 33.6 vs 27.5 among those aged 45 to 49 years, 49.8 vs 32.2 among those aged 50 to 54 years, and 178.5 vs 39.2 among those aged 55 to 59 years.⁴ Among published literature reviews, members of the US Air Force (USAF) had the highest rates of melanoma compared to other military branches, with an incidence rate of 7.6 vs 6.3 among USAF males vs Army males and 9.0 vs 5.5 among USAF females vs Army females.⁴ These findings were further supported by another study showing a higher incidence rate of melanoma in USAF members compared to Army personnel (17.8 vs 9.5) and a 62% greater melanoma incidence in active-duty military personnel compared to the general population when adjusted for age, race, sex, and year of diagnosis.⁵ Additionally, a meta-analysis reported a standardized incidence ratio of 1.4 (95% CI, 1.1-1.9) for malignant melanoma and 1.8 (95% CI, 1.3-2.8) for NMSC among military pilots compared to the general population.⁶ It is important to note that these data are limited to published peer-reviewed studies within PubMed and may not reflect the true skin cancer incidence.

More comprehensive studies are needed to compare NMSC incidence rates in nonpilot military populations compared to the general population. From 2005 to 2014, the average annual NMSC incidence rate in the USAF was 64.4 per 100,000 person-years, with the highest rate at 97.4 per 100,000 person-years in 2007.⁷ However, this study did not directly compare military service members to the general population. Service in tropical environments among World War II veterans was associated with an increased risk for NMSC. Sixty-six percent of patients with BCC (n=197) and 68% with squamous cell carcinoma (SCC)(n=41) were stationed in the Pacific, despite the number and demographics of soldiers deployed to the Pacific and Europe being approximately equal.⁸ During a 6-month period in 2008, a Combat Dermatology Clinic in Iraq showed 5% (n=129) of visits were for treatment of actinic keratoses (AKs), while 8% of visits (n=205) were related to skin cancer, including BCC, SCC, mycosis fungoides, and melanoma.⁹ Overall, these studies confirm a higher rate of melanoma in military service members vs the general population and indicate USAF members may be at the greatest risk for developing melanoma and NMSC among the service branches. Further studies are needed to elucidate why this might be the case and should concentrate on demographics, service locations, uniform wear and personal protective equipment standards, and use of sun-protective measures across each service branch.

Our search yielded no aggregate studies to determine if there is an increased rate of other types of skin cancer in military service members such as Merkel cell carcinoma, dermatofibrosarcoma protuberans, and microcystic adnexal carcinoma (MAC). Gerall et al¹⁰ described a case of MAC in a 43-year-old USAF U-2 pilot with a 15-year history of a slow-growing soft-tissue nodule on the cheek. The patient’s young age differed from the typical age of MAC occurrence (ie, 60–70 years), which led to the possibility that his profession contributed to the development of MAC and the relatively young age of onset.¹⁰

Etiology of Disease

The results of our literature review indicated that skin cancers are more prevalent among active-duty military personnel and veterans than in the general population; they also suggest that frequent sun exposure and lack of sun protection may be key etiologic factors. In 2015, only 23% of veterans (n=49) reported receiving skin cancer awareness education from the US Military.¹ Among soldiers returning from Iraq and Afghanistan (n=212), only 13% reported routine sunscreen use, and less than 30% reported having routine access to sunscreen while working more than 4 hours per day in direct sunlight or 75% of the day working in direct sunlight. Of these, the majority reported sustaining at least 1 sunburn, while 43% had at least 2 sunburns and 20% reported a history of a blistering sunburn during deployment.¹ The intermittent exposure hypothesis—defined as the theory that intense periods of exposure to UV radiation increase the risk for melanoma more than chronic cumulative UV radiation exposure—may explain how occupational exposure in the military may lead to increased skin cancer incidence. Individuals exposed to brief periods of intense, inconsistent, or unpredictable UV radiation may lack protective adaptive mechanisms compared to those who are chronically exposed.²

Exposure to UV radiation at higher altitudes (with corresponding higher UV energy) and altered sleep-wake cycles (with resulting altered immune defenses) may contribute to higher rates of melanoma and NMSC among USAF pilots.¹¹ During a 57-minute flight at 30,000-ft altitude, a pilot is exposed to a UVA dose equivalent to 20 minutes inside a tanning booth.¹² Although UVB transmission through plastic and glass windshields was reported to be less than 1%, UVA transmission ranged from 0.4% to 53.5%. The UVA dose for a pilot flying a light aircraft in Las Vegas, Nevada, was reported to be 127 μW/cm² at ground level vs 242 μW/cm² at a 30,000-ft altitude.¹² Therefore, cosmic radiation exposure for military pilots is higher than for commercial pilots, as they fly at higher altitudes. U-2 pilots are exposed to 20 times the cosmic radiation dose at sea level and 10 times the exposure of commercial pilots.¹⁰

It currently is unknown why service in the USAF would increase skin cancer risk compared to service in other branches; however, there are some differences between military branches that require further research, including ethnic demographics, uniform wear and personal protective equipment standards, duty assignment locations, and the hours the military members are asked to work outside with direct sunlight exposure for each branch of service. Environmental exposures may differ based on the military branch gear requirements; for example, when on the flight line or flight deck, USN aircrews are required to wear cranials (helmets), eyewear (visor or goggles), and long-sleeved shirts. When at sea, USN flight crews wear gloves, headgear, goggles, pants, and long-sleeved shirts to identify their duty onboard. All of these measures offer good sun protection and are carried over to the land-based flight lines in the USN and Marine Corps. Neither the Army nor the USAF commonly utilize these practices. Conversely, the USAF does not allow flight line workers including fuelers, maintainers, and aircrew to wear coveralls due to the risk of being blown off, becoming foreign object debris, and being sucked into jet engines. However, in-flight protective gear such as goggles, gloves, and coveralls are worn.¹² Perhaps the USAF may attract, recruit, or commission people with inherently more risk for skin cancer (eg, White individuals). How racial and ethnic factors may affect skin cancer incidence in military branches is an area for future research efforts.

Recommendations

Given the considerable increase in risk factors, efforts are needed to reduce the disparity in skin cancer rates between US military personnel and their civilian counterparts through appropriate prevention, screening, and intervention programs.

Prevention—In wartime settings as well as in training and other peacetime activities, active-duty military members cannot avoid harmful midday sun exposure. Additionally, application and reapplication of sunscreen can be challenging. Sunscreen, broad-spectrum lip balm, and wide-brimmed “boonie” hats can be ordered by supply personnel.¹³ We recommend that a standard sunscreen supply be available to all active-duty military service members. The long-sleeved, tightly woven fabric of military uniforms also can provide protection from the sun but can be difficult to tolerate for extended periods of time in warm climates. Breathable, lightweight, sun-protective clothing is commercially available and could be incorporated into military uniforms.

All service members should be educated about skin cancer risks while addressing common myths and inaccuracies. Fifty percent (n=50) of surveyed veterans thought discussions of skin cancer prevention and safety during basic training could help prevent skin cancer in service members.¹⁴ Suggestions from respondents included education about sun exposure consequences, use of graphic images of skin cancer in teaching, providing protective clothing and sunscreen to active-duty military service members, and discussion about sun protection with physicians during annual physicals. When veterans with a history of skin cancer were surveyed about their personal risk for skin cancer, most believed they were at little risk (average perceived risk response score, 2.2 out of 5 [1=no risk; 5=high risk]).¹⁴ The majority explained that they did not seek sun protection after warnings of skin cancer risk because they did not think skin cancer would happen to them,¹⁴ though the incidence of NMSC in the United States at the time of these surveys was estimated to be 3.5 million per year.^14,15 Another study found that only 13% of veterans knew the back is the most common site of melanoma in men.¹ The Army Public Health Center has informational fact sheets available online or in dermatologists’ offices that detail correct sunscreen application techniques and how to reduce sun exposure.^16,17 However, military service members reported that they prefer physicians to communicate with them directly about skin cancer risks vs reading brochures in physician offices or gaining information from television, radio, military training, or the Internet (4.4 out 5 rating for communication methods of risks associated with skin cancer [1=ineffective; 5=very effective]).¹⁴ However, only 27% of nondermatologist physicians counseled or screened their patients on skin cancer or sunscreen yearly, 49% even less frequently, with 24% never counseling or screening at all. Because not all service members may be able to regularly see a dermatologist, efforts should be focused on increasing primary care physician awareness on counseling and screening.¹⁸

Early Detection—Military service members should be educated on how to perform skin self-examinations to alert their providers earlier to concerning lesions. The American Academy of Dermatology publishes infographics regarding the ABCDEs of melanoma and how to perform skin self-examinations.^19,20 Although the US Preventive Services Task Force concluded there was insufficient evidence to recommend skin self-examination for all adults, the increased risk that military service members and veterans have requires further studies to examine the utility of self-screening in this population.²⁰ Given the evidence of a higher incidence of melanoma in military service members vs the general population after 45 years of age,⁴ we recommend starting yearly in-person screenings performed by primary care physicians or dermatologists at this age. Ensuring every service member has routine in-office skin examinations can be difficult given the limited number of active-duty military dermatologists. Civilian dermatologists also could be helpful in this respect.

Teleconsultation, teledermoscopy, or store-and-forward imaging services for concerning lesions could be utilized when in-person consultations with a dermatologist are not feasible or cannot be performed in a timely manner. From 2004 to 2012, 40% of 10,817 teleconsultations were dermatology consultations from deployed or remote environments.²¹ Teleconsultation can be performed via email through the global military teleconsultation portal.²² These methods can lead to earlier detection of skin cancer rather than delaying evaluation for an in-person consultation.²³

Intervention—High-risk patients who have been diagnosed with NMSC or many AKs should consider oral, procedural, or topical chemoprevention to reduce the risk for additional skin cancers as both primary and secondary prevention. In a double-blind, randomized, controlled trial of 386 individuals with a history of 2 or more NMSCs, participants were randomly assigned to receive either 500 mg of nicotinamide twice daily or placebo for 12 months. Compared to the placebo group, the nicotinamide group had a 23% lower rate of new NMSCs and an 11% lower rate of new AKs at 12 months.²⁴ The use of acitretin also has been studied in transplant recipients for the chemoprevention of NMSC. In a double-blind, randomized, controlled trial of renal transplant recipients with more than 10 AKs randomized to receive either 30 mg/d of acitretin or placebo for 6 months, 11% of the acitretin group reported a new NMSC compared to 47% in the placebo group.²⁵ An open-label study of 27 renal transplant recipients treated with methyl-esterified aminolevulinic acid–photodynamic therapy and red light demonstrated an increased mean time to occurrence of an AK, SCC, BCC, keratoacanthoma, or wart from 6.8 months in untreated areas compared to 9.6 months in treated areas.²⁵ In active-duty locations where access to red and blue light sources is unavailable, the use of daylight photodynamic therapy can be considered, as it does not require any special equipment. Topical treatments such as 5-fluorouracil and imiquimod can be used for treatment and chemoprevention of NMSC. In a follow-up study from the Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial, patients who applied 5-fluorouracil cream 5% twice daily to the face and ears for 4 weeks had a 75% risk reduction in developing SCC requiring surgery compared to the control group for the first year after treatment.^26,27

Final Thoughts

Focusing on the efforts we propose can help the US Military expand their prevention, screening, and intervention programs for skin cancer in service members. Further research can then be performed to determine which programs have the greatest impact on rates of skin cancer among military and veteran personnel. Given these higher incidences and risk of exposure for skin cancer among service members, the various services may consider mandating sunscreen use as part of the uniform to prevent skin cancer. To maximize effectiveness, these efforts to prevent the development of skin cancer among military and veteran personnel should be adopted nationally.