Dermatopathology

Plasma cell cheilitis (PCC), also known as plasmocytosis circumorificialis and plasmocytosis mucosae,¹ is a poorly understood, uncommon inflammatory condition characterized by dense infiltration of mature plasma cells in the mucosal dermis of the lip.^2-5 The etiology of PCC is unknown but is thought to be a reactive immune process triggered by infection, mechanical friction, trauma, or solar damage.^1,5,6

The most common presentation of PCC is a slowly evolving, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 Secondary changes with disease progression can include erosion, ulceration, fissures, edema, bleeding, or crusting.⁵ The diagnosis of PCC is challenging because it can mimic neoplastic, infectious, and inflammatory conditions.^8,9

Treatment strategies for PCC described in the literature vary, as does therapeutic response. Resolution of PCC has been documented after systemic steroids, intralesional steroids, systemic griseofulvin, and topical calcineurin inhibitors, among other agents.^6,7,10-16

We present the case of a patient with a lip lesion who ultimately was diagnosed with PCC after it progressed to an advanced necrotic stage.

Case Report

An 80-year-old male veteran of the Armed Services initially presented to our institution via teledermatology with redness and crusting of the lower lip (Figure 1). He had a history of myelodysplastic syndrome and anemia requiring iron transfusion. The process appeared to be consistent with actinic cheilitis vs squamous cell carcinoma. In-person dermatology consultation was recommended; however, the patient did not follow through with that appointment.

Five months later, additional photographs of the lesion were taken by the patient's primary care physician and sent through teledermatology, revealing progression to an erythematous, yellow-crusted erosion (Figure 2). The medical record indicated that a punch biopsy performed by the patient’s primary care physician showed hyperkeratosis and fungal organisms on periodic acid–Schiff staining. He subsequently applied ketoconazole and terbinafine cream to the lower lip without improvement. Prompt in-person evaluation by dermatology was again recommended.

Comment

The diagnosis and management of PCC is difficult because the condition is uncommon (though its true incidence is unknown) and the presentation is nonspecific, invoking a wide differential diagnosis. In the literature, PCC presents as a slowly progressive, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 The lesion can progress to become eroded, ulcerated, fissured, or edematous.⁵

Differential Diagnosis
The clinical differential diagnosis of PCC is broad and includes inflammatory, infectious, and neoplastic causes, such as actinic cheilitis, allergic contact cheilitis, exfoliative cheilitis, granulomatous cheilitis, lichen planus, candidiasis, syphilis, and squamous cell carcinoma of the lip.^7,9 The histologic differential diagnosis includes allergic contact cheilitis, secondary syphilis, actinic cheilitis, squamous cell carcinoma, cheilitis granulomatosa, and plasmacytoma.^17-19

Histopathology
On biopsy, PCC usually is characterized by plasma cells in a bandlike pattern in the upper submucosa or even more diffusely throughout the submucosa.²⁰ In earlier studies, polyclonality of plasma cells with kappa and lambda light chains has been demonstrated⁵; in this case, such polyclonality militated against a plasma cell dyscrasia. There have been reports of a various number of eosinophils in PCC,^5,20 but eosinophils were not a prominent feature in our case.

Treatment
As reported in the literature, treatment of PCC has been attempted using a broad range of strategies; however, the optimal regimen has yet to be elucidated.¹⁵ Numerous therapies, including excision, radiation, electrocauterization, cryotherapy, steroids, systemic griseofulvin, topical fusidic acid, and topical calcineurin inhibitors, have yielded variable success.^6,7,10-16

The success of topical corticosteroids, as demonstrated in our case, has been unpredictable; the reported response has ranged from complete resolution to failure.⁹ This variability is thought to be related to epithelial width and the degree of acanthosis, with ulcerative lesions demonstrating a superior response to topical corticosteroids.⁹

Conclusion

Our case highlights the challenges of diagnosing and managing PCC, especially through teledermatology. Initial photographs of the lesion (Figure 1) that were submitted demonstrated a nonspecific erosion, which was concerning for any of several infectious, inflammatory, and malignant causes. Prompt in-person evaluation was warranted; regrettably, the patient’s condition worsened rapidly in the 10 days it took for him to be seen in-person by dermatology.

Furthermore, this case necessitated 3 separate biopsies because the pathology on the first 2 biopsies initially was equivocal, demonstrating ulceration and granulation tissue. The diagnosis was finally made after a third biopsy was recommended by a dermatopathologist, who eventually identified a bandlike distribution of polyclonal plasma cells in the upper submucosa, consistent with a diagnosis of PCC. Our patient’s final disease presentation (Figure 3) was exuberant and may represent the end point of untreated PCC.

Plasma cell cheilitis (PCC), also known as plasmocytosis circumorificialis and plasmocytosis mucosae,¹ is a poorly understood, uncommon inflammatory condition characterized by dense infiltration of mature plasma cells in the mucosal dermis of the lip.^2-5 The etiology of PCC is unknown but is thought to be a reactive immune process triggered by infection, mechanical friction, trauma, or solar damage.^1,5,6

The most common presentation of PCC is a slowly evolving, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 Secondary changes with disease progression can include erosion, ulceration, fissures, edema, bleeding, or crusting.⁵ The diagnosis of PCC is challenging because it can mimic neoplastic, infectious, and inflammatory conditions.^8,9

Treatment strategies for PCC described in the literature vary, as does therapeutic response. Resolution of PCC has been documented after systemic steroids, intralesional steroids, systemic griseofulvin, and topical calcineurin inhibitors, among other agents.^6,7,10-16

We present the case of a patient with a lip lesion who ultimately was diagnosed with PCC after it progressed to an advanced necrotic stage.

Case Report

An 80-year-old male veteran of the Armed Services initially presented to our institution via teledermatology with redness and crusting of the lower lip (Figure 1). He had a history of myelodysplastic syndrome and anemia requiring iron transfusion. The process appeared to be consistent with actinic cheilitis vs squamous cell carcinoma. In-person dermatology consultation was recommended; however, the patient did not follow through with that appointment.

Five months later, additional photographs of the lesion were taken by the patient's primary care physician and sent through teledermatology, revealing progression to an erythematous, yellow-crusted erosion (Figure 2). The medical record indicated that a punch biopsy performed by the patient’s primary care physician showed hyperkeratosis and fungal organisms on periodic acid–Schiff staining. He subsequently applied ketoconazole and terbinafine cream to the lower lip without improvement. Prompt in-person evaluation by dermatology was again recommended.

Comment

The diagnosis and management of PCC is difficult because the condition is uncommon (though its true incidence is unknown) and the presentation is nonspecific, invoking a wide differential diagnosis. In the literature, PCC presents as a slowly progressive, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 The lesion can progress to become eroded, ulcerated, fissured, or edematous.⁵

Differential Diagnosis
The clinical differential diagnosis of PCC is broad and includes inflammatory, infectious, and neoplastic causes, such as actinic cheilitis, allergic contact cheilitis, exfoliative cheilitis, granulomatous cheilitis, lichen planus, candidiasis, syphilis, and squamous cell carcinoma of the lip.^7,9 The histologic differential diagnosis includes allergic contact cheilitis, secondary syphilis, actinic cheilitis, squamous cell carcinoma, cheilitis granulomatosa, and plasmacytoma.^17-19

Histopathology
On biopsy, PCC usually is characterized by plasma cells in a bandlike pattern in the upper submucosa or even more diffusely throughout the submucosa.²⁰ In earlier studies, polyclonality of plasma cells with kappa and lambda light chains has been demonstrated⁵; in this case, such polyclonality militated against a plasma cell dyscrasia. There have been reports of a various number of eosinophils in PCC,^5,20 but eosinophils were not a prominent feature in our case.

Treatment
As reported in the literature, treatment of PCC has been attempted using a broad range of strategies; however, the optimal regimen has yet to be elucidated.¹⁵ Numerous therapies, including excision, radiation, electrocauterization, cryotherapy, steroids, systemic griseofulvin, topical fusidic acid, and topical calcineurin inhibitors, have yielded variable success.^6,7,10-16

The success of topical corticosteroids, as demonstrated in our case, has been unpredictable; the reported response has ranged from complete resolution to failure.⁹ This variability is thought to be related to epithelial width and the degree of acanthosis, with ulcerative lesions demonstrating a superior response to topical corticosteroids.⁹

Conclusion

Our case highlights the challenges of diagnosing and managing PCC, especially through teledermatology. Initial photographs of the lesion (Figure 1) that were submitted demonstrated a nonspecific erosion, which was concerning for any of several infectious, inflammatory, and malignant causes. Prompt in-person evaluation was warranted; regrettably, the patient’s condition worsened rapidly in the 10 days it took for him to be seen in-person by dermatology.

Furthermore, this case necessitated 3 separate biopsies because the pathology on the first 2 biopsies initially was equivocal, demonstrating ulceration and granulation tissue. The diagnosis was finally made after a third biopsy was recommended by a dermatopathologist, who eventually identified a bandlike distribution of polyclonal plasma cells in the upper submucosa, consistent with a diagnosis of PCC. Our patient’s final disease presentation (Figure 3) was exuberant and may represent the end point of untreated PCC.

Plasma cell cheilitis (PCC), also known as plasmocytosis circumorificialis and plasmocytosis mucosae,¹ is a poorly understood, uncommon inflammatory condition characterized by dense infiltration of mature plasma cells in the mucosal dermis of the lip.^2-5 The etiology of PCC is unknown but is thought to be a reactive immune process triggered by infection, mechanical friction, trauma, or solar damage.^1,5,6

The most common presentation of PCC is a slowly evolving, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 Secondary changes with disease progression can include erosion, ulceration, fissures, edema, bleeding, or crusting.⁵ The diagnosis of PCC is challenging because it can mimic neoplastic, infectious, and inflammatory conditions.^8,9

Treatment strategies for PCC described in the literature vary, as does therapeutic response. Resolution of PCC has been documented after systemic steroids, intralesional steroids, systemic griseofulvin, and topical calcineurin inhibitors, among other agents.^6,7,10-16

We present the case of a patient with a lip lesion who ultimately was diagnosed with PCC after it progressed to an advanced necrotic stage.

Case Report

An 80-year-old male veteran of the Armed Services initially presented to our institution via teledermatology with redness and crusting of the lower lip (Figure 1). He had a history of myelodysplastic syndrome and anemia requiring iron transfusion. The process appeared to be consistent with actinic cheilitis vs squamous cell carcinoma. In-person dermatology consultation was recommended; however, the patient did not follow through with that appointment.

Five months later, additional photographs of the lesion were taken by the patient's primary care physician and sent through teledermatology, revealing progression to an erythematous, yellow-crusted erosion (Figure 2). The medical record indicated that a punch biopsy performed by the patient’s primary care physician showed hyperkeratosis and fungal organisms on periodic acid–Schiff staining. He subsequently applied ketoconazole and terbinafine cream to the lower lip without improvement. Prompt in-person evaluation by dermatology was again recommended.

Comment

The diagnosis and management of PCC is difficult because the condition is uncommon (though its true incidence is unknown) and the presentation is nonspecific, invoking a wide differential diagnosis. In the literature, PCC presents as a slowly progressive, red-brown patch or plaque on the lower lip in older individuals.^2,3,5,7 The lesion can progress to become eroded, ulcerated, fissured, or edematous.⁵

Differential Diagnosis
The clinical differential diagnosis of PCC is broad and includes inflammatory, infectious, and neoplastic causes, such as actinic cheilitis, allergic contact cheilitis, exfoliative cheilitis, granulomatous cheilitis, lichen planus, candidiasis, syphilis, and squamous cell carcinoma of the lip.^7,9 The histologic differential diagnosis includes allergic contact cheilitis, secondary syphilis, actinic cheilitis, squamous cell carcinoma, cheilitis granulomatosa, and plasmacytoma.^17-19

Histopathology
On biopsy, PCC usually is characterized by plasma cells in a bandlike pattern in the upper submucosa or even more diffusely throughout the submucosa.²⁰ In earlier studies, polyclonality of plasma cells with kappa and lambda light chains has been demonstrated⁵; in this case, such polyclonality militated against a plasma cell dyscrasia. There have been reports of a various number of eosinophils in PCC,^5,20 but eosinophils were not a prominent feature in our case.

Treatment
As reported in the literature, treatment of PCC has been attempted using a broad range of strategies; however, the optimal regimen has yet to be elucidated.¹⁵ Numerous therapies, including excision, radiation, electrocauterization, cryotherapy, steroids, systemic griseofulvin, topical fusidic acid, and topical calcineurin inhibitors, have yielded variable success.^6,7,10-16

The success of topical corticosteroids, as demonstrated in our case, has been unpredictable; the reported response has ranged from complete resolution to failure.⁹ This variability is thought to be related to epithelial width and the degree of acanthosis, with ulcerative lesions demonstrating a superior response to topical corticosteroids.⁹

Conclusion

Our case highlights the challenges of diagnosing and managing PCC, especially through teledermatology. Initial photographs of the lesion (Figure 1) that were submitted demonstrated a nonspecific erosion, which was concerning for any of several infectious, inflammatory, and malignant causes. Prompt in-person evaluation was warranted; regrettably, the patient’s condition worsened rapidly in the 10 days it took for him to be seen in-person by dermatology.

Furthermore, this case necessitated 3 separate biopsies because the pathology on the first 2 biopsies initially was equivocal, demonstrating ulceration and granulation tissue. The diagnosis was finally made after a third biopsy was recommended by a dermatopathologist, who eventually identified a bandlike distribution of polyclonal plasma cells in the upper submucosa, consistent with a diagnosis of PCC. Our patient’s final disease presentation (Figure 3) was exuberant and may represent the end point of untreated PCC.

To the Editor:

The art of tattooing continues to gain popularity in the 21st century, albeit with accompanying hazards.¹ Reported adverse reactions to tattoos include infections, tumors, and hypersensitivity and granulomatous reactions.² Various infectious agents may involve tattoos, including human papillomavirus (HPV), molluscum contagiosum, herpes simplex virus, hepatitis C virus, tuberculoid and nontuberculoid mycobacteria, and Staphylococcus aureus.² Verruca vulgaris infrequently has been reported to develop in tattoos.^3,4 Previously reported cases of verruca in tattoos suggest a predilection for blue or black pigment.^1-5 We report a case of verruca vulgaris occurring within the red-inked areas of a tattoo that first appeared approximately 18 years after the initial tattoo placement.

A 44-year-old woman presented with erythema, induration, and irritation of a tattoo on the left leg of 2 years’ duration. The tattoo initially was inscribed more than 20 years prior. The patient had a history of type 2 diabetes mellitus and chronic obstructive pulmonary disease. She reported no prior trauma to the area, prior rash or irritation, or similar changes to her other tattoos, including those with red ink. The affected tattoo was inscribed at a separate time from the other tattoos. Physical examination of the irritated tattoo revealed hyperkeratotic papules with firm scaling in the zone of dermal red pigment (Figure 1). Notable nodularity or deep induration was not present. The clinical differential diagnosis included a hypersensitivity reaction to red tattoo ink, sarcoidosis, and an infectious process, such as an atypical mycobacterial infection. A punch biopsy demonstrated papillomatous epidermal hyperplasia with hyperkeratosis, focal parakeratosis, and frequent vacuolization of keratinocytes with enlarged keratohyalin granules, diagnostic of verruca vulgaris (Figure 2). Of note, the patient did not have clinically apparent viral warts elsewhere on physical examination. The patient was successfully managedwith a combination of 2 treatments of intralesional Candida antigen and 3 treatments of cryotherapy with resolution of most lesions over the course of 8 months. Over the following several months, the patient applied topical salicylic acid, which led to the resolution of the remaining lesions. The verrucae had not recurred 19 months after the initial presentation.

The development of verruca vulgaris within a tattoo may occur secondary to various mechanisms of HPV inoculation, including introduction of the virus through contaminated ink, the tattoo artist’s saliva, autoinoculation, or koebnerization of a pre-existing verruca vulgaris.⁴ Local immune system dysregulation secondary to tattoo ink also has been proposed as a mechanism for HPV infection in this setting.^1,5 The contents of darker tattoo pigments may promote formation of reactive oxygen species inducing local immunocompromise.⁵

The pathogenic mechanism was elusive in our patient. Although the localization of verruca vulgaris to the zones of red pigment may be merely coincidental, this phenomenon raised suspicion for direct inoculation via contaminated red ink. The patient’s other red ink–containing tattoos that were inscribed separately were spared, compatible with contamination of the red ink used for the affected tattoo. However, the delayed onset of nearly 2 decades was exceptional, given the shorter previously reported latencies ranging from months to 10 years.⁴ Autoinoculation or koebnerization is plausible, though greater involvement of nonred pigments would be expected as well as a briefer latency. Finally, the possibility of local immune dysregulation seemed feasible, given the slow evolution of the lesions largely restricted to one pigment type.

We report a case of verruca vulgaris within the red area of a multicolored tattoo that occurred approximately 18 years after tattoo placement. This case highlights a rare presentation of an infectious agent that may complicate tattoos. Both predilection for red pigment rather than black or blue pigment and the long latency period raised interesting questions regarding pathogenesis. Confirmatory biopsy enables effective management of this tattoo complication.

To the Editor:

The art of tattooing continues to gain popularity in the 21st century, albeit with accompanying hazards.¹ Reported adverse reactions to tattoos include infections, tumors, and hypersensitivity and granulomatous reactions.² Various infectious agents may involve tattoos, including human papillomavirus (HPV), molluscum contagiosum, herpes simplex virus, hepatitis C virus, tuberculoid and nontuberculoid mycobacteria, and Staphylococcus aureus.² Verruca vulgaris infrequently has been reported to develop in tattoos.^3,4 Previously reported cases of verruca in tattoos suggest a predilection for blue or black pigment.^1-5 We report a case of verruca vulgaris occurring within the red-inked areas of a tattoo that first appeared approximately 18 years after the initial tattoo placement.

A 44-year-old woman presented with erythema, induration, and irritation of a tattoo on the left leg of 2 years’ duration. The tattoo initially was inscribed more than 20 years prior. The patient had a history of type 2 diabetes mellitus and chronic obstructive pulmonary disease. She reported no prior trauma to the area, prior rash or irritation, or similar changes to her other tattoos, including those with red ink. The affected tattoo was inscribed at a separate time from the other tattoos. Physical examination of the irritated tattoo revealed hyperkeratotic papules with firm scaling in the zone of dermal red pigment (Figure 1). Notable nodularity or deep induration was not present. The clinical differential diagnosis included a hypersensitivity reaction to red tattoo ink, sarcoidosis, and an infectious process, such as an atypical mycobacterial infection. A punch biopsy demonstrated papillomatous epidermal hyperplasia with hyperkeratosis, focal parakeratosis, and frequent vacuolization of keratinocytes with enlarged keratohyalin granules, diagnostic of verruca vulgaris (Figure 2). Of note, the patient did not have clinically apparent viral warts elsewhere on physical examination. The patient was successfully managedwith a combination of 2 treatments of intralesional Candida antigen and 3 treatments of cryotherapy with resolution of most lesions over the course of 8 months. Over the following several months, the patient applied topical salicylic acid, which led to the resolution of the remaining lesions. The verrucae had not recurred 19 months after the initial presentation.

The development of verruca vulgaris within a tattoo may occur secondary to various mechanisms of HPV inoculation, including introduction of the virus through contaminated ink, the tattoo artist’s saliva, autoinoculation, or koebnerization of a pre-existing verruca vulgaris.⁴ Local immune system dysregulation secondary to tattoo ink also has been proposed as a mechanism for HPV infection in this setting.^1,5 The contents of darker tattoo pigments may promote formation of reactive oxygen species inducing local immunocompromise.⁵

The pathogenic mechanism was elusive in our patient. Although the localization of verruca vulgaris to the zones of red pigment may be merely coincidental, this phenomenon raised suspicion for direct inoculation via contaminated red ink. The patient’s other red ink–containing tattoos that were inscribed separately were spared, compatible with contamination of the red ink used for the affected tattoo. However, the delayed onset of nearly 2 decades was exceptional, given the shorter previously reported latencies ranging from months to 10 years.⁴ Autoinoculation or koebnerization is plausible, though greater involvement of nonred pigments would be expected as well as a briefer latency. Finally, the possibility of local immune dysregulation seemed feasible, given the slow evolution of the lesions largely restricted to one pigment type.

We report a case of verruca vulgaris within the red area of a multicolored tattoo that occurred approximately 18 years after tattoo placement. This case highlights a rare presentation of an infectious agent that may complicate tattoos. Both predilection for red pigment rather than black or blue pigment and the long latency period raised interesting questions regarding pathogenesis. Confirmatory biopsy enables effective management of this tattoo complication.

To the Editor:

The art of tattooing continues to gain popularity in the 21st century, albeit with accompanying hazards.¹ Reported adverse reactions to tattoos include infections, tumors, and hypersensitivity and granulomatous reactions.² Various infectious agents may involve tattoos, including human papillomavirus (HPV), molluscum contagiosum, herpes simplex virus, hepatitis C virus, tuberculoid and nontuberculoid mycobacteria, and Staphylococcus aureus.² Verruca vulgaris infrequently has been reported to develop in tattoos.^3,4 Previously reported cases of verruca in tattoos suggest a predilection for blue or black pigment.^1-5 We report a case of verruca vulgaris occurring within the red-inked areas of a tattoo that first appeared approximately 18 years after the initial tattoo placement.

A 44-year-old woman presented with erythema, induration, and irritation of a tattoo on the left leg of 2 years’ duration. The tattoo initially was inscribed more than 20 years prior. The patient had a history of type 2 diabetes mellitus and chronic obstructive pulmonary disease. She reported no prior trauma to the area, prior rash or irritation, or similar changes to her other tattoos, including those with red ink. The affected tattoo was inscribed at a separate time from the other tattoos. Physical examination of the irritated tattoo revealed hyperkeratotic papules with firm scaling in the zone of dermal red pigment (Figure 1). Notable nodularity or deep induration was not present. The clinical differential diagnosis included a hypersensitivity reaction to red tattoo ink, sarcoidosis, and an infectious process, such as an atypical mycobacterial infection. A punch biopsy demonstrated papillomatous epidermal hyperplasia with hyperkeratosis, focal parakeratosis, and frequent vacuolization of keratinocytes with enlarged keratohyalin granules, diagnostic of verruca vulgaris (Figure 2). Of note, the patient did not have clinically apparent viral warts elsewhere on physical examination. The patient was successfully managedwith a combination of 2 treatments of intralesional Candida antigen and 3 treatments of cryotherapy with resolution of most lesions over the course of 8 months. Over the following several months, the patient applied topical salicylic acid, which led to the resolution of the remaining lesions. The verrucae had not recurred 19 months after the initial presentation.

The development of verruca vulgaris within a tattoo may occur secondary to various mechanisms of HPV inoculation, including introduction of the virus through contaminated ink, the tattoo artist’s saliva, autoinoculation, or koebnerization of a pre-existing verruca vulgaris.⁴ Local immune system dysregulation secondary to tattoo ink also has been proposed as a mechanism for HPV infection in this setting.^1,5 The contents of darker tattoo pigments may promote formation of reactive oxygen species inducing local immunocompromise.⁵

The pathogenic mechanism was elusive in our patient. Although the localization of verruca vulgaris to the zones of red pigment may be merely coincidental, this phenomenon raised suspicion for direct inoculation via contaminated red ink. The patient’s other red ink–containing tattoos that were inscribed separately were spared, compatible with contamination of the red ink used for the affected tattoo. However, the delayed onset of nearly 2 decades was exceptional, given the shorter previously reported latencies ranging from months to 10 years.⁴ Autoinoculation or koebnerization is plausible, though greater involvement of nonred pigments would be expected as well as a briefer latency. Finally, the possibility of local immune dysregulation seemed feasible, given the slow evolution of the lesions largely restricted to one pigment type.

We report a case of verruca vulgaris within the red area of a multicolored tattoo that occurred approximately 18 years after tattoo placement. This case highlights a rare presentation of an infectious agent that may complicate tattoos. Both predilection for red pigment rather than black or blue pigment and the long latency period raised interesting questions regarding pathogenesis. Confirmatory biopsy enables effective management of this tattoo complication.

The Diagnosis: Pemphigus Foliaceous

Laboratory workup including a complete blood cell count with differential, comprehensive metabolic panel, antinuclear antibodies, Sjögren syndrome A and B antibodies, hepatitis profile, rapid plasma reagin, HIV screen, aldolase, anti–Jo-1, T-Spot TB test (Quest Diagnostics), and tissue cultures was unremarkable. Two 4-mm punch biopsies were obtained from the left cheek and upper back, both of which demonstrated intragranular acantholysis suggestive of pemphigus foliaceous (Figure 1A). A subsequent punch biopsy from the right lower abdomen sent for direct immunofluorescence demonstrated netlike positivity of IgG and C3 in the upper epidermis (Figure 1B), and serum sent for indirect immunofluorescence demonstrated intercellular IgG antibodies to desmoglein (Dsg) 1 on monkey esophagus and positive Dsg-1 antibodies on enzyme-linked immunosorbent assay, confirming the diagnosis.

The patient was started on a 60-mg prednisone taper as well as dapsone 50 mg daily; the dapsone was titrated up to 100 mg daily. After tapering down to 10 mg daily of prednisone over 2 months and continuing dapsone with minimal improvement, he was given 2 infusions of rituximab 1000 mg 2 weeks apart. The scalp plaque was dramatically improved at 3-month follow-up (Figure 2), with partial improvement of the cheek plaques (Figure 3). Dapsone was increased to 150 mg daily, and he was encouraged to use triamcinolone acetonide ointment 0.1% twice daily, which led to further improvement.

Pemphigus foliaceus is an autoimmune blistering disease that most commonly occurs in middle-aged adults. It generally is less common than pemphigus vulgaris, except in Finland, Tunisia, and Brazil, where there is an endemic condition with an identical clinical and histological presentation known as fogo selvagem.¹

The pathogenesis of pemphigus foliaceous is characterized by IgG autoantibodies against Dsg-1, a transmembrane glycoprotein involved in the cellular adhesion of keratinocytes, which is preferentially expressed in the superficial epidermis.^2-7 Dysfunction of Dsg-1 results in the separation of superficial epidermal cells, resulting in intraepidermal blisters.^2,7 In contrast to pemphigus vulgaris, there typically is a lack of oral mucosal involvement due to compensation by Dsg-3 in the mucosa.⁴ Potential triggers for pemphigus foliaceous include exposure to UV radiation; radiotherapy; pregnancy; physiologic stress; and drugs, most commonly captopril, penicillamine, and thiols.⁸

Pemphigus foliaceous lesions clinically appear as eroded and crusted lesions on an erythematous base, commonly in a seborrheic distribution on the face, scalp, and trunk with sparing of the oral mucosa,^2,6 but lesions can progress to a widespread and more severe exfoliative dermatitis.⁷ Lesions also can appear as psoriasiform plaques and often are initially misdiagnosed as psoriasis, particularly in patients with skin of color.^9,10

Diagnosis of pemphigus foliaceous typically is made using a combination of histology as well as both direct and indirect immunofluorescence. Histologically, pemphigus foliaceus presents with subcorneal acantholysis, which is most prominent in the granular layer and occasionally the presence of neutrophils and eosinophils in the blister cavity.⁷ Direct immunofluorescence demonstrates netlike intercellular IgG and C3 in the upper portion of the epidermis.¹¹ Indirect immunofluorescence can help detect circulating IgG antibodies to Dsg-1, with guinea pig esophagus being the ideal substrate.^11,12

First-line treatment of pemphigus foliaceus consists of systemic glucocorticoid therapy, often administered with azathioprine, methotrexate, or mycophenolate mofetil.^2,6,13 Although first-line treatment is effective in 60% to 80% of patients,² relapsing cases can be treated with cyclophosphamide, intravenous immunoglobulin, immunoadsorption, plasmapheresis, or rituximab.²

Rituximab is a chimeric monoclonal antibody targeting CD20⁺ B cells, leading to decreased antibody production, which has been shown to be effective in treating severe and refractory cases of pemphigus foliaceus.^6,13Rituximab with short-course prednisone has been found to be more effective in achieving complete remission at 24 months than prednisone alone.¹⁴ In patients with contraindications to systemic glucocorticoid therapy, rituximab has been shown as an effective first-line therapy.¹⁵ One-quarter of patients treated with rituximab relapsed within 2 years of treatment⁶ (average time to relapse, 6–26 months).¹⁶ High-dose rituximab regimens, along with a higher number of rituximab treatment cycles, have been shown to prolong time to relapse.⁶ Further, higher baseline levels of Dsg-1 antibody have been correlated to earlier relapse and can be used following rituximab therapy to monitor disease progression.^6,16

The differential diagnosis for pemphigus foliaceous includes disseminated blastomycosis, hypertrophic lupus erythematosus, sebopsoriasis, and secondary syphilis. Disseminated blastomycosis presents with cutaneous manifestations such as nodules, papules, or pustules evolving over weeks to months into ulcers with subsequent scarring.¹⁷ Hypertrophic lupus erythematosus presents with papules and nodules with associated keratotic scaling on the face, palms, and extensor surfaces of the limbs.¹⁸ Sebopsoriasis is characterized by well-defined lesions with an overlying scale distributed on the scalp, face, and chest.¹⁹ Secondary syphilis presents as early hyperpigmented macules transitioning to acral papulosquamous lesions involving the palms and soles.²⁰

The Diagnosis: Pemphigus Foliaceous

Laboratory workup including a complete blood cell count with differential, comprehensive metabolic panel, antinuclear antibodies, Sjögren syndrome A and B antibodies, hepatitis profile, rapid plasma reagin, HIV screen, aldolase, anti–Jo-1, T-Spot TB test (Quest Diagnostics), and tissue cultures was unremarkable. Two 4-mm punch biopsies were obtained from the left cheek and upper back, both of which demonstrated intragranular acantholysis suggestive of pemphigus foliaceous (Figure 1A). A subsequent punch biopsy from the right lower abdomen sent for direct immunofluorescence demonstrated netlike positivity of IgG and C3 in the upper epidermis (Figure 1B), and serum sent for indirect immunofluorescence demonstrated intercellular IgG antibodies to desmoglein (Dsg) 1 on monkey esophagus and positive Dsg-1 antibodies on enzyme-linked immunosorbent assay, confirming the diagnosis.

The patient was started on a 60-mg prednisone taper as well as dapsone 50 mg daily; the dapsone was titrated up to 100 mg daily. After tapering down to 10 mg daily of prednisone over 2 months and continuing dapsone with minimal improvement, he was given 2 infusions of rituximab 1000 mg 2 weeks apart. The scalp plaque was dramatically improved at 3-month follow-up (Figure 2), with partial improvement of the cheek plaques (Figure 3). Dapsone was increased to 150 mg daily, and he was encouraged to use triamcinolone acetonide ointment 0.1% twice daily, which led to further improvement.

Pemphigus foliaceus is an autoimmune blistering disease that most commonly occurs in middle-aged adults. It generally is less common than pemphigus vulgaris, except in Finland, Tunisia, and Brazil, where there is an endemic condition with an identical clinical and histological presentation known as fogo selvagem.¹

The pathogenesis of pemphigus foliaceous is characterized by IgG autoantibodies against Dsg-1, a transmembrane glycoprotein involved in the cellular adhesion of keratinocytes, which is preferentially expressed in the superficial epidermis.^2-7 Dysfunction of Dsg-1 results in the separation of superficial epidermal cells, resulting in intraepidermal blisters.^2,7 In contrast to pemphigus vulgaris, there typically is a lack of oral mucosal involvement due to compensation by Dsg-3 in the mucosa.⁴ Potential triggers for pemphigus foliaceous include exposure to UV radiation; radiotherapy; pregnancy; physiologic stress; and drugs, most commonly captopril, penicillamine, and thiols.⁸

Pemphigus foliaceous lesions clinically appear as eroded and crusted lesions on an erythematous base, commonly in a seborrheic distribution on the face, scalp, and trunk with sparing of the oral mucosa,^2,6 but lesions can progress to a widespread and more severe exfoliative dermatitis.⁷ Lesions also can appear as psoriasiform plaques and often are initially misdiagnosed as psoriasis, particularly in patients with skin of color.^9,10

Diagnosis of pemphigus foliaceous typically is made using a combination of histology as well as both direct and indirect immunofluorescence. Histologically, pemphigus foliaceus presents with subcorneal acantholysis, which is most prominent in the granular layer and occasionally the presence of neutrophils and eosinophils in the blister cavity.⁷ Direct immunofluorescence demonstrates netlike intercellular IgG and C3 in the upper portion of the epidermis.¹¹ Indirect immunofluorescence can help detect circulating IgG antibodies to Dsg-1, with guinea pig esophagus being the ideal substrate.^11,12

First-line treatment of pemphigus foliaceus consists of systemic glucocorticoid therapy, often administered with azathioprine, methotrexate, or mycophenolate mofetil.^2,6,13 Although first-line treatment is effective in 60% to 80% of patients,² relapsing cases can be treated with cyclophosphamide, intravenous immunoglobulin, immunoadsorption, plasmapheresis, or rituximab.²

Rituximab is a chimeric monoclonal antibody targeting CD20⁺ B cells, leading to decreased antibody production, which has been shown to be effective in treating severe and refractory cases of pemphigus foliaceus.^6,13Rituximab with short-course prednisone has been found to be more effective in achieving complete remission at 24 months than prednisone alone.¹⁴ In patients with contraindications to systemic glucocorticoid therapy, rituximab has been shown as an effective first-line therapy.¹⁵ One-quarter of patients treated with rituximab relapsed within 2 years of treatment⁶ (average time to relapse, 6–26 months).¹⁶ High-dose rituximab regimens, along with a higher number of rituximab treatment cycles, have been shown to prolong time to relapse.⁶ Further, higher baseline levels of Dsg-1 antibody have been correlated to earlier relapse and can be used following rituximab therapy to monitor disease progression.^6,16

The differential diagnosis for pemphigus foliaceous includes disseminated blastomycosis, hypertrophic lupus erythematosus, sebopsoriasis, and secondary syphilis. Disseminated blastomycosis presents with cutaneous manifestations such as nodules, papules, or pustules evolving over weeks to months into ulcers with subsequent scarring.¹⁷ Hypertrophic lupus erythematosus presents with papules and nodules with associated keratotic scaling on the face, palms, and extensor surfaces of the limbs.¹⁸ Sebopsoriasis is characterized by well-defined lesions with an overlying scale distributed on the scalp, face, and chest.¹⁹ Secondary syphilis presents as early hyperpigmented macules transitioning to acral papulosquamous lesions involving the palms and soles.²⁰

The Diagnosis: Pemphigus Foliaceous

Laboratory workup including a complete blood cell count with differential, comprehensive metabolic panel, antinuclear antibodies, Sjögren syndrome A and B antibodies, hepatitis profile, rapid plasma reagin, HIV screen, aldolase, anti–Jo-1, T-Spot TB test (Quest Diagnostics), and tissue cultures was unremarkable. Two 4-mm punch biopsies were obtained from the left cheek and upper back, both of which demonstrated intragranular acantholysis suggestive of pemphigus foliaceous (Figure 1A). A subsequent punch biopsy from the right lower abdomen sent for direct immunofluorescence demonstrated netlike positivity of IgG and C3 in the upper epidermis (Figure 1B), and serum sent for indirect immunofluorescence demonstrated intercellular IgG antibodies to desmoglein (Dsg) 1 on monkey esophagus and positive Dsg-1 antibodies on enzyme-linked immunosorbent assay, confirming the diagnosis.

The patient was started on a 60-mg prednisone taper as well as dapsone 50 mg daily; the dapsone was titrated up to 100 mg daily. After tapering down to 10 mg daily of prednisone over 2 months and continuing dapsone with minimal improvement, he was given 2 infusions of rituximab 1000 mg 2 weeks apart. The scalp plaque was dramatically improved at 3-month follow-up (Figure 2), with partial improvement of the cheek plaques (Figure 3). Dapsone was increased to 150 mg daily, and he was encouraged to use triamcinolone acetonide ointment 0.1% twice daily, which led to further improvement.

Pemphigus foliaceus is an autoimmune blistering disease that most commonly occurs in middle-aged adults. It generally is less common than pemphigus vulgaris, except in Finland, Tunisia, and Brazil, where there is an endemic condition with an identical clinical and histological presentation known as fogo selvagem.¹

The pathogenesis of pemphigus foliaceous is characterized by IgG autoantibodies against Dsg-1, a transmembrane glycoprotein involved in the cellular adhesion of keratinocytes, which is preferentially expressed in the superficial epidermis.^2-7 Dysfunction of Dsg-1 results in the separation of superficial epidermal cells, resulting in intraepidermal blisters.^2,7 In contrast to pemphigus vulgaris, there typically is a lack of oral mucosal involvement due to compensation by Dsg-3 in the mucosa.⁴ Potential triggers for pemphigus foliaceous include exposure to UV radiation; radiotherapy; pregnancy; physiologic stress; and drugs, most commonly captopril, penicillamine, and thiols.⁸

Pemphigus foliaceous lesions clinically appear as eroded and crusted lesions on an erythematous base, commonly in a seborrheic distribution on the face, scalp, and trunk with sparing of the oral mucosa,^2,6 but lesions can progress to a widespread and more severe exfoliative dermatitis.⁷ Lesions also can appear as psoriasiform plaques and often are initially misdiagnosed as psoriasis, particularly in patients with skin of color.^9,10

Diagnosis of pemphigus foliaceous typically is made using a combination of histology as well as both direct and indirect immunofluorescence. Histologically, pemphigus foliaceus presents with subcorneal acantholysis, which is most prominent in the granular layer and occasionally the presence of neutrophils and eosinophils in the blister cavity.⁷ Direct immunofluorescence demonstrates netlike intercellular IgG and C3 in the upper portion of the epidermis.¹¹ Indirect immunofluorescence can help detect circulating IgG antibodies to Dsg-1, with guinea pig esophagus being the ideal substrate.^11,12

First-line treatment of pemphigus foliaceus consists of systemic glucocorticoid therapy, often administered with azathioprine, methotrexate, or mycophenolate mofetil.^2,6,13 Although first-line treatment is effective in 60% to 80% of patients,² relapsing cases can be treated with cyclophosphamide, intravenous immunoglobulin, immunoadsorption, plasmapheresis, or rituximab.²

Rituximab is a chimeric monoclonal antibody targeting CD20⁺ B cells, leading to decreased antibody production, which has been shown to be effective in treating severe and refractory cases of pemphigus foliaceus.^6,13Rituximab with short-course prednisone has been found to be more effective in achieving complete remission at 24 months than prednisone alone.¹⁴ In patients with contraindications to systemic glucocorticoid therapy, rituximab has been shown as an effective first-line therapy.¹⁵ One-quarter of patients treated with rituximab relapsed within 2 years of treatment⁶ (average time to relapse, 6–26 months).¹⁶ High-dose rituximab regimens, along with a higher number of rituximab treatment cycles, have been shown to prolong time to relapse.⁶ Further, higher baseline levels of Dsg-1 antibody have been correlated to earlier relapse and can be used following rituximab therapy to monitor disease progression.^6,16

The differential diagnosis for pemphigus foliaceous includes disseminated blastomycosis, hypertrophic lupus erythematosus, sebopsoriasis, and secondary syphilis. Disseminated blastomycosis presents with cutaneous manifestations such as nodules, papules, or pustules evolving over weeks to months into ulcers with subsequent scarring.¹⁷ Hypertrophic lupus erythematosus presents with papules and nodules with associated keratotic scaling on the face, palms, and extensor surfaces of the limbs.¹⁸ Sebopsoriasis is characterized by well-defined lesions with an overlying scale distributed on the scalp, face, and chest.¹⁹ Secondary syphilis presents as early hyperpigmented macules transitioning to acral papulosquamous lesions involving the palms and soles.²⁰

To the Editor:

Protothecosis infections are caused by an achlorophyllic algae of the species Prototheca. Prototheca organisms are found mostly in soil and water.¹ Human infections are rare and involve 2 species, Prototheca wickerhamii and Prototheca zopfii. The former most commonly is responsible for human infections, though P zopfii results in more serious systemic infections with a poor prognosis. There are various types of Prototheca infection presentations, with a 2007 review of 117 cases reporting that cutaneous infections are most common (66%), followed by systemic infections (19%), and olecranon bursitis (15%).² Skin lesions most commonly occur on the extremities and face, and they present as vesiculobullous and ulcerative lesions with purulent drainage. The skin lesions also may appear as erythematous plaques or nodules, subcutaneous papules, verrucous or herpetiformis lesions, or pyogenic granuloma–like lesions.³ Protothecosis typically affects immunocompromised individuals, especially those with a history of chronic corticosteroid use, malignancy, diabetes mellitus, AIDS, and/or organ transplant.¹ We present a case of cutaneous protothecosis on the dorsal distal extremity of a 94-year-old woman. History of exposure to soil while gardening was elicited from the patient, and no immunosuppressive history was present aside from the patient’s age. This case may prompt workup for malignancy or immunosuppression in this patient subset.

A 94-year-old woman with a medical history of cutaneous squamous cell carcinoma (SCC) presented with a growing lesion on the dorsal surface of the left fourth digit of 2 months’ duration. The patient reported the lesion was painful, and she noted preceding trauma to the area that was suspected to have occurred while gardening. Physical examination revealed an ulcerated, hypertrophic, erythematous nodule on the dorsal surface of the left fourth metacarpophalangeal joint. The differential diagnosis included SCC, inflamed cyst, verruca vulgaris, and orf virus due to the clinical presentation. A shave biopsy was performed, and the lesion subsequently was treated with electrodesiccation and curettage.

Histopathologic evaluation revealed pseudoepitheliomatous hyperplasia with a mixed inflammatory infiltrate including lymphocytes and histiocytes. A morula within the dermis was characteristic of a protothecosis infection (Figure 1). On follow-up visit 6 weeks later, the lesion had grown back to its original size and morphology (Figure 2). At this time, the lesion was again treated with shave removal, followed by electrodesiccation and curettage, and the patient was placed on oral fluconazole 200 mg daily for 1 month. When the lesion did not resolve with fluconazole, she was referred to infectious disease as well as general surgery for surgical removal and debridement of the lesion. Unfortunately, the patient was lost to follow-up.

Protothecosis is an infectious disease comprised of achlorophyllic algae found in soil and water that rarely affects humans. When it does affect humans, cutaneous infections are most common. All human cases in which organisms were identified to species level have been caused by P wickerhamii or P zopfii species.² Inoculation is suspected to occur through trauma to affected skin, especially when in the context of contaminated water. Our patient reported history of trauma to the hand, with soil from gardening as the potential aquagenic source of the infection.

The clinical presentation of protothecosis ranges from localized cutaneous to disseminated systemic infections, with most reported cases of systemic disease occurring in immunocompromised individuals. The cutaneous lesions of protothecosis vary greatly in clinical appearance including ulcerative nodules (as in our case), papules, plaques, pustules, and vesicles with erosion or crusting.⁴

Cutaneous protothecosis has the potential to mimic many other skin diseases and lesions, and, given its rarity, it may not be on the radar of dermatologists. Our patient’s lesion was presumed to be a skin cancer and was treated as such because of the history of SCC and clinical presentation. Although excision of individual lesions of protothecosis can be curative, electrodesiccation and curettage does not appear to be an adequate treatment, as the lesion subsequently recurred. It also is possible that this case represents P zopfii infection, as it did not respond to treatment with oral fluconazole, though in vitro studies with fluconazole to both P zopfii and P wickerhamii had variable treatment success.² Also, the histopathologic findings were most consistent with P wickerhamii, revealing small, round, symmetrical morula, compared to P zopfii, which typically will display oval or cylindrical, asymmetrical, random internal segmentation.⁵ This case may warrant determination of species, which can be accomplished by a culture on Sabouraud dextrose agar, carbohydrate and alcohol assimilation test, yeast biochemical card, serological typing by immunoblotting, immunofluorescence study using species-specific antibodies, or amplification by polymerase chain reaction for small subunit ribosomal DNA sequences.^2,6-8

The natural history of isolated skin disease is an indolent progressive course; however, reports do exist noting spontaneous resolution.^4,9 Treatment options for Prototheca infections can be disappointing and consist of both surgical and medical management, or a combination of the 2 approaches. Reports in the literature support the use of antifungals including ketoconazole, voriconazole, itraconazole, fluconazole, and amphotericin B, with the latter displaying the best activity against Prototheca species.² Tetracycline has been used in combination with oral or topical amphotericin B and was found to be synergistic in vitro and in case reports at successfully treating cutaneous protothecosis infections. It is possible that our patient was not treated with fluconazole long enough for it to become therapeutic, as most reported treatment regimens are weeks to months in length. Conversely, it may have been of benefit to transition the patient to topical amphotericin B and tetracycline, as fluconazole failed in this patient. However, treatment successes and failures are limited to case reports/case series and in vitro studies, with prospective studies lacking. Due to the variability with in vitro susceptibility profiles for Prototheca species, it generally is not recommended to pursue in vitro susceptibility testing in the management of Prototheca skin infections due to the inconsistency demonstrated between in vitro activity and clinical response to therapy.²

To the Editor:

Protothecosis infections are caused by an achlorophyllic algae of the species Prototheca. Prototheca organisms are found mostly in soil and water.¹ Human infections are rare and involve 2 species, Prototheca wickerhamii and Prototheca zopfii. The former most commonly is responsible for human infections, though P zopfii results in more serious systemic infections with a poor prognosis. There are various types of Prototheca infection presentations, with a 2007 review of 117 cases reporting that cutaneous infections are most common (66%), followed by systemic infections (19%), and olecranon bursitis (15%).² Skin lesions most commonly occur on the extremities and face, and they present as vesiculobullous and ulcerative lesions with purulent drainage. The skin lesions also may appear as erythematous plaques or nodules, subcutaneous papules, verrucous or herpetiformis lesions, or pyogenic granuloma–like lesions.³ Protothecosis typically affects immunocompromised individuals, especially those with a history of chronic corticosteroid use, malignancy, diabetes mellitus, AIDS, and/or organ transplant.¹ We present a case of cutaneous protothecosis on the dorsal distal extremity of a 94-year-old woman. History of exposure to soil while gardening was elicited from the patient, and no immunosuppressive history was present aside from the patient’s age. This case may prompt workup for malignancy or immunosuppression in this patient subset.

A 94-year-old woman with a medical history of cutaneous squamous cell carcinoma (SCC) presented with a growing lesion on the dorsal surface of the left fourth digit of 2 months’ duration. The patient reported the lesion was painful, and she noted preceding trauma to the area that was suspected to have occurred while gardening. Physical examination revealed an ulcerated, hypertrophic, erythematous nodule on the dorsal surface of the left fourth metacarpophalangeal joint. The differential diagnosis included SCC, inflamed cyst, verruca vulgaris, and orf virus due to the clinical presentation. A shave biopsy was performed, and the lesion subsequently was treated with electrodesiccation and curettage.

Histopathologic evaluation revealed pseudoepitheliomatous hyperplasia with a mixed inflammatory infiltrate including lymphocytes and histiocytes. A morula within the dermis was characteristic of a protothecosis infection (Figure 1). On follow-up visit 6 weeks later, the lesion had grown back to its original size and morphology (Figure 2). At this time, the lesion was again treated with shave removal, followed by electrodesiccation and curettage, and the patient was placed on oral fluconazole 200 mg daily for 1 month. When the lesion did not resolve with fluconazole, she was referred to infectious disease as well as general surgery for surgical removal and debridement of the lesion. Unfortunately, the patient was lost to follow-up.

Protothecosis is an infectious disease comprised of achlorophyllic algae found in soil and water that rarely affects humans. When it does affect humans, cutaneous infections are most common. All human cases in which organisms were identified to species level have been caused by P wickerhamii or P zopfii species.² Inoculation is suspected to occur through trauma to affected skin, especially when in the context of contaminated water. Our patient reported history of trauma to the hand, with soil from gardening as the potential aquagenic source of the infection.

The clinical presentation of protothecosis ranges from localized cutaneous to disseminated systemic infections, with most reported cases of systemic disease occurring in immunocompromised individuals. The cutaneous lesions of protothecosis vary greatly in clinical appearance including ulcerative nodules (as in our case), papules, plaques, pustules, and vesicles with erosion or crusting.⁴

Cutaneous protothecosis has the potential to mimic many other skin diseases and lesions, and, given its rarity, it may not be on the radar of dermatologists. Our patient’s lesion was presumed to be a skin cancer and was treated as such because of the history of SCC and clinical presentation. Although excision of individual lesions of protothecosis can be curative, electrodesiccation and curettage does not appear to be an adequate treatment, as the lesion subsequently recurred. It also is possible that this case represents P zopfii infection, as it did not respond to treatment with oral fluconazole, though in vitro studies with fluconazole to both P zopfii and P wickerhamii had variable treatment success.² Also, the histopathologic findings were most consistent with P wickerhamii, revealing small, round, symmetrical morula, compared to P zopfii, which typically will display oval or cylindrical, asymmetrical, random internal segmentation.⁵ This case may warrant determination of species, which can be accomplished by a culture on Sabouraud dextrose agar, carbohydrate and alcohol assimilation test, yeast biochemical card, serological typing by immunoblotting, immunofluorescence study using species-specific antibodies, or amplification by polymerase chain reaction for small subunit ribosomal DNA sequences.^2,6-8

The natural history of isolated skin disease is an indolent progressive course; however, reports do exist noting spontaneous resolution.^4,9 Treatment options for Prototheca infections can be disappointing and consist of both surgical and medical management, or a combination of the 2 approaches. Reports in the literature support the use of antifungals including ketoconazole, voriconazole, itraconazole, fluconazole, and amphotericin B, with the latter displaying the best activity against Prototheca species.² Tetracycline has been used in combination with oral or topical amphotericin B and was found to be synergistic in vitro and in case reports at successfully treating cutaneous protothecosis infections. It is possible that our patient was not treated with fluconazole long enough for it to become therapeutic, as most reported treatment regimens are weeks to months in length. Conversely, it may have been of benefit to transition the patient to topical amphotericin B and tetracycline, as fluconazole failed in this patient. However, treatment successes and failures are limited to case reports/case series and in vitro studies, with prospective studies lacking. Due to the variability with in vitro susceptibility profiles for Prototheca species, it generally is not recommended to pursue in vitro susceptibility testing in the management of Prototheca skin infections due to the inconsistency demonstrated between in vitro activity and clinical response to therapy.²

To the Editor:

Protothecosis infections are caused by an achlorophyllic algae of the species Prototheca. Prototheca organisms are found mostly in soil and water.¹ Human infections are rare and involve 2 species, Prototheca wickerhamii and Prototheca zopfii. The former most commonly is responsible for human infections, though P zopfii results in more serious systemic infections with a poor prognosis. There are various types of Prototheca infection presentations, with a 2007 review of 117 cases reporting that cutaneous infections are most common (66%), followed by systemic infections (19%), and olecranon bursitis (15%).² Skin lesions most commonly occur on the extremities and face, and they present as vesiculobullous and ulcerative lesions with purulent drainage. The skin lesions also may appear as erythematous plaques or nodules, subcutaneous papules, verrucous or herpetiformis lesions, or pyogenic granuloma–like lesions.³ Protothecosis typically affects immunocompromised individuals, especially those with a history of chronic corticosteroid use, malignancy, diabetes mellitus, AIDS, and/or organ transplant.¹ We present a case of cutaneous protothecosis on the dorsal distal extremity of a 94-year-old woman. History of exposure to soil while gardening was elicited from the patient, and no immunosuppressive history was present aside from the patient’s age. This case may prompt workup for malignancy or immunosuppression in this patient subset.

A 94-year-old woman with a medical history of cutaneous squamous cell carcinoma (SCC) presented with a growing lesion on the dorsal surface of the left fourth digit of 2 months’ duration. The patient reported the lesion was painful, and she noted preceding trauma to the area that was suspected to have occurred while gardening. Physical examination revealed an ulcerated, hypertrophic, erythematous nodule on the dorsal surface of the left fourth metacarpophalangeal joint. The differential diagnosis included SCC, inflamed cyst, verruca vulgaris, and orf virus due to the clinical presentation. A shave biopsy was performed, and the lesion subsequently was treated with electrodesiccation and curettage.

Histopathologic evaluation revealed pseudoepitheliomatous hyperplasia with a mixed inflammatory infiltrate including lymphocytes and histiocytes. A morula within the dermis was characteristic of a protothecosis infection (Figure 1). On follow-up visit 6 weeks later, the lesion had grown back to its original size and morphology (Figure 2). At this time, the lesion was again treated with shave removal, followed by electrodesiccation and curettage, and the patient was placed on oral fluconazole 200 mg daily for 1 month. When the lesion did not resolve with fluconazole, she was referred to infectious disease as well as general surgery for surgical removal and debridement of the lesion. Unfortunately, the patient was lost to follow-up.

Protothecosis is an infectious disease comprised of achlorophyllic algae found in soil and water that rarely affects humans. When it does affect humans, cutaneous infections are most common. All human cases in which organisms were identified to species level have been caused by P wickerhamii or P zopfii species.² Inoculation is suspected to occur through trauma to affected skin, especially when in the context of contaminated water. Our patient reported history of trauma to the hand, with soil from gardening as the potential aquagenic source of the infection.

The clinical presentation of protothecosis ranges from localized cutaneous to disseminated systemic infections, with most reported cases of systemic disease occurring in immunocompromised individuals. The cutaneous lesions of protothecosis vary greatly in clinical appearance including ulcerative nodules (as in our case), papules, plaques, pustules, and vesicles with erosion or crusting.⁴

Cutaneous protothecosis has the potential to mimic many other skin diseases and lesions, and, given its rarity, it may not be on the radar of dermatologists. Our patient’s lesion was presumed to be a skin cancer and was treated as such because of the history of SCC and clinical presentation. Although excision of individual lesions of protothecosis can be curative, electrodesiccation and curettage does not appear to be an adequate treatment, as the lesion subsequently recurred. It also is possible that this case represents P zopfii infection, as it did not respond to treatment with oral fluconazole, though in vitro studies with fluconazole to both P zopfii and P wickerhamii had variable treatment success.² Also, the histopathologic findings were most consistent with P wickerhamii, revealing small, round, symmetrical morula, compared to P zopfii, which typically will display oval or cylindrical, asymmetrical, random internal segmentation.⁵ This case may warrant determination of species, which can be accomplished by a culture on Sabouraud dextrose agar, carbohydrate and alcohol assimilation test, yeast biochemical card, serological typing by immunoblotting, immunofluorescence study using species-specific antibodies, or amplification by polymerase chain reaction for small subunit ribosomal DNA sequences.^2,6-8

The natural history of isolated skin disease is an indolent progressive course; however, reports do exist noting spontaneous resolution.^4,9 Treatment options for Prototheca infections can be disappointing and consist of both surgical and medical management, or a combination of the 2 approaches. Reports in the literature support the use of antifungals including ketoconazole, voriconazole, itraconazole, fluconazole, and amphotericin B, with the latter displaying the best activity against Prototheca species.² Tetracycline has been used in combination with oral or topical amphotericin B and was found to be synergistic in vitro and in case reports at successfully treating cutaneous protothecosis infections. It is possible that our patient was not treated with fluconazole long enough for it to become therapeutic, as most reported treatment regimens are weeks to months in length. Conversely, it may have been of benefit to transition the patient to topical amphotericin B and tetracycline, as fluconazole failed in this patient. However, treatment successes and failures are limited to case reports/case series and in vitro studies, with prospective studies lacking. Due to the variability with in vitro susceptibility profiles for Prototheca species, it generally is not recommended to pursue in vitro susceptibility testing in the management of Prototheca skin infections due to the inconsistency demonstrated between in vitro activity and clinical response to therapy.²

To the Editor:

Verrucous carcinoma is a rare, well-differentiated, locally aggressive squamous cell carcinoma first described by Ackerman in 1948.¹ There are 4 main clinicopathologic types: oral florid papillomatosis or Ackerman tumor, giant condyloma acuminatum or Buschke-Lowenstein tumor, plantar verrucous carcinoma, and cutaneous verrucous carcinoma.^2,3 Historically, most patients are older white men. The lesion commonly occurs in sites of inflammation⁴ or chronic irritation/trauma. Clinically, patients present with a slowly enlarging, exophytic, verrucous plaque violating the skin, fascia, and occasionally bone. Although these lesions have little tendency to metastasize, substantial morbidity can be seen due to local invasion. Despite surgical excision, recurrence is not uncommon and is associated with a poor prognosis and higher infiltrative potential.⁵

A 45-year-old male veteran initially presented to our dermatology clinic with a 4-cm, macerated, verrucous plaque on the left lateral ankle in the area of a skin graft placed during a prior limb salvage surgery (Figure 1). The patient experienced a traumatic blast injury while deployed 7 years prior with a subsequent right-sided below-the-knee amputation and left lower limb salvage. The lesion was clinically diagnosed as verruca vulgaris and treated with daily salicylic acid. Six weeks after the initial presentation, the lesion remained largely unchanged. A biopsy subsequently was obtained to confirm the diagnosis. At that time, the histopathology was consistent with verruca vulgaris without evidence of carcinoma. Due to the persistence of the lesion, lack of improvement with topical treatment, and overall size, the patient opted for surgical excision.

Verrucous carcinoma can represent a diagnostic dilemma, as histologic sections may mimic benign entities. The features of a well-differentiated squamous epithelium with hyperkeratosis, papillomatosis, and acanthosis can be mistaken for verruca vulgaris, keratoacanthoma, and pseudoepitheliomatous hyperplasia,⁶ which are characteristic of verrucous hyperplasia. Accurate diagnosis can be difficult with a superficial biopsy because of the mature appearance of the epithelium,⁷ prompting the need for multiple and deeper biopsies⁸ to include sampling of the base of the hyperplastic epithelium in which the characteristic bulbous pushing growth pattern of the rete ridges is visualized. Precise histologic diagnosis can be further confounded by external mechanical factors, such as pressure, which can distort the classic histopathology.⁷ The histopathologic features leading to the diagnosis of verrucous carcinoma in our specimen were minimal squamous atypia present in a predominantly exophytic squamous proliferation with human papillomavirus cytopathic effect and focal endophytic pushing borders by rounded bulbous rete ridges into the mid and deep dermis (Figure 2).

To the Editor:

Verrucous carcinoma is a rare, well-differentiated, locally aggressive squamous cell carcinoma first described by Ackerman in 1948.¹ There are 4 main clinicopathologic types: oral florid papillomatosis or Ackerman tumor, giant condyloma acuminatum or Buschke-Lowenstein tumor, plantar verrucous carcinoma, and cutaneous verrucous carcinoma.^2,3 Historically, most patients are older white men. The lesion commonly occurs in sites of inflammation⁴ or chronic irritation/trauma. Clinically, patients present with a slowly enlarging, exophytic, verrucous plaque violating the skin, fascia, and occasionally bone. Although these lesions have little tendency to metastasize, substantial morbidity can be seen due to local invasion. Despite surgical excision, recurrence is not uncommon and is associated with a poor prognosis and higher infiltrative potential.⁵

A 45-year-old male veteran initially presented to our dermatology clinic with a 4-cm, macerated, verrucous plaque on the left lateral ankle in the area of a skin graft placed during a prior limb salvage surgery (Figure 1). The patient experienced a traumatic blast injury while deployed 7 years prior with a subsequent right-sided below-the-knee amputation and left lower limb salvage. The lesion was clinically diagnosed as verruca vulgaris and treated with daily salicylic acid. Six weeks after the initial presentation, the lesion remained largely unchanged. A biopsy subsequently was obtained to confirm the diagnosis. At that time, the histopathology was consistent with verruca vulgaris without evidence of carcinoma. Due to the persistence of the lesion, lack of improvement with topical treatment, and overall size, the patient opted for surgical excision.

Verrucous carcinoma can represent a diagnostic dilemma, as histologic sections may mimic benign entities. The features of a well-differentiated squamous epithelium with hyperkeratosis, papillomatosis, and acanthosis can be mistaken for verruca vulgaris, keratoacanthoma, and pseudoepitheliomatous hyperplasia,⁶ which are characteristic of verrucous hyperplasia. Accurate diagnosis can be difficult with a superficial biopsy because of the mature appearance of the epithelium,⁷ prompting the need for multiple and deeper biopsies⁸ to include sampling of the base of the hyperplastic epithelium in which the characteristic bulbous pushing growth pattern of the rete ridges is visualized. Precise histologic diagnosis can be further confounded by external mechanical factors, such as pressure, which can distort the classic histopathology.⁷ The histopathologic features leading to the diagnosis of verrucous carcinoma in our specimen were minimal squamous atypia present in a predominantly exophytic squamous proliferation with human papillomavirus cytopathic effect and focal endophytic pushing borders by rounded bulbous rete ridges into the mid and deep dermis (Figure 2).

To the Editor:

Verrucous carcinoma is a rare, well-differentiated, locally aggressive squamous cell carcinoma first described by Ackerman in 1948.¹ There are 4 main clinicopathologic types: oral florid papillomatosis or Ackerman tumor, giant condyloma acuminatum or Buschke-Lowenstein tumor, plantar verrucous carcinoma, and cutaneous verrucous carcinoma.^2,3 Historically, most patients are older white men. The lesion commonly occurs in sites of inflammation⁴ or chronic irritation/trauma. Clinically, patients present with a slowly enlarging, exophytic, verrucous plaque violating the skin, fascia, and occasionally bone. Although these lesions have little tendency to metastasize, substantial morbidity can be seen due to local invasion. Despite surgical excision, recurrence is not uncommon and is associated with a poor prognosis and higher infiltrative potential.⁵

A 45-year-old male veteran initially presented to our dermatology clinic with a 4-cm, macerated, verrucous plaque on the left lateral ankle in the area of a skin graft placed during a prior limb salvage surgery (Figure 1). The patient experienced a traumatic blast injury while deployed 7 years prior with a subsequent right-sided below-the-knee amputation and left lower limb salvage. The lesion was clinically diagnosed as verruca vulgaris and treated with daily salicylic acid. Six weeks after the initial presentation, the lesion remained largely unchanged. A biopsy subsequently was obtained to confirm the diagnosis. At that time, the histopathology was consistent with verruca vulgaris without evidence of carcinoma. Due to the persistence of the lesion, lack of improvement with topical treatment, and overall size, the patient opted for surgical excision.

Verrucous carcinoma can represent a diagnostic dilemma, as histologic sections may mimic benign entities. The features of a well-differentiated squamous epithelium with hyperkeratosis, papillomatosis, and acanthosis can be mistaken for verruca vulgaris, keratoacanthoma, and pseudoepitheliomatous hyperplasia,⁶ which are characteristic of verrucous hyperplasia. Accurate diagnosis can be difficult with a superficial biopsy because of the mature appearance of the epithelium,⁷ prompting the need for multiple and deeper biopsies⁸ to include sampling of the base of the hyperplastic epithelium in which the characteristic bulbous pushing growth pattern of the rete ridges is visualized. Precise histologic diagnosis can be further confounded by external mechanical factors, such as pressure, which can distort the classic histopathology.⁷ The histopathologic features leading to the diagnosis of verrucous carcinoma in our specimen were minimal squamous atypia present in a predominantly exophytic squamous proliferation with human papillomavirus cytopathic effect and focal endophytic pushing borders by rounded bulbous rete ridges into the mid and deep dermis (Figure 2).

The Diagnosis: Levamisole-Induced Vasculopathy

Biopsy of one of the bullous retiform purpura on the leg (Figure 1) revealed a combined leukocytoclastic vasculitis and thrombotic vasculopathy (quiz images). Periodic acid-Schiff and Gram stains, with adequate controls, were negative for pathogenic fungal and bacterial organisms. Although this reaction pattern has an extensive differential, in this clinical setting with associated cocaine-positive urine toxicologic analysis, perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), and leukopenia, the histopathologic findings were consistent with levamisole-induced vasculopathy (LIV).^1,2 Although not specific, leukocytoclastic vasculitis and thrombotic vasculopathy have been reported as the classic histopathologic findings of LIV. In addition, interstitial and perivascular neovascularization have been reported as a potential histopathologic finding associated with this entity but was not seen in our case.³  

Levamisole is an anthelminthic agent used to adulterate cocaine, a practice first noted in 2003 with increasing incidence.¹ Both levamisole and cocaine stimulate the sympathetic nervous system by increasing dopamine in the euphoric areas of the brain.^1,3 By combining the 2 substances, preparation costs are reduced and stimulant effects are enhanced. It is estimated that 69% to 80% of cocaine in the United States is contaminated with levamisole.^2,4,5 The constellation of findings seen in patients abusing levamisole-contaminated cocaine include agranulocytosis; p-ANCA; and a tender, vasculitic, retiform purpura presentation. The most common sites for the purpura include the cheeks and ears. The purpura can progress to bullous lesions, as seen in our patient, followed by necrosis.^4,6 Recurrent use of levamisole-contaminated cocaine is associated with recurrent agranulocytosis and classic skin findings, which is suggestive of a causal relationship.⁶  

Serologic testing for levamisole exposure presents a challenge. The half-life of levamisole is relatively short (estimated at 5.6 hours) and is found in urine samples approximately 3% of the time.^1,3,6 The volatile diagnostic characteristics of levamisole make concrete laboratory confirmation difficult. Although a skin biopsy can be helpful to rule out other causes of vasculitislike presentations, it is not specific for LIV. Therefore, clinical suspicion for LIV should remain high in patients who present with the cutaneous findings described as well as agranulocytosis, positive p-ANCA, and a history of cocaine use with a skin biopsy showing leukocytoclastic vasculitis and thrombotic vasculopathy.  

The differential diagnosis for LIV with retiform bullous lesions includes several other vasculitides and vesiculobullous diseases. Eosinophilic granulomatosis with polyangiitis (EGPA) is a multisystem vasculitis that is characterized by eosinophilia, asthma, and rhinosinusitis. Eosinophilic granulomatosis with polyangiitis primarily affects small and medium arteries in the skin and respiratory tract and occurs in 3 stages: prodromal, eosinophilic, and vasculitic. These stages are characterized by mild asthma or rhinitis, eosinophilia with multiorgan infiltration, and vasculitis with extravascular granulomatosis, respectively. Diagnosis often is clinical based on these findings and laboratory evaluation. Eosinophilic granulomatosis with polyangiitis presents with positive p-ANCA in 40% to 60% of patients.⁷ The vasculitis stage of EGPA presents with cutaneous findings in 60% of cases, including palpable purpura, infiltrated papules and plaques, urticaria, necrotizing lesions, and rarely vesicles and bullae.⁸ Classic histopathologic features include leukocytoclastic or eosinophilic vasculitis, an eosinophilic infiltrate, granuloma formation, and eosinophilic granule deposition onto collagen fibrils (otherwise known as flame figures)(Figure 2). Biopsy of these lesions with the aforementioned findings, in constellation with the described systemic signs and symptoms, can aid in diagnosis of EGPA.  

Polyarteritis nodosa (PAN) is a vasculitis that can be either multisystem or limited to one organ. Classic PAN affects the small- to medium-sized vessels. When there is multisystem involvement, it most often affects the skin, gastrointestinal tract, and kidneys. It presents with subcutaneous or dermal nodules, necrotic lesions, livedo reticularis, hypertension, abdominal pain, and an acute abdomen.⁹ When PAN is in its limited form, it most commonly occurs in the skin. The cutaneous manifestations of skin-limited PAN are identical to classic PAN, most commonly occurring on the legs and arms and less often on the trunk, head, and neck.¹⁰ To aid in diagnosis, biopsies of cutaneous lesions are beneficial. Dermatopathologic examination of PAN reveals fibrinoid necrosis of small and medium vessels with a perivascular mononuclear inflammatory infiltrate (Figure 3). Cutaneous PAN rarely progresses to multisystem classic PAN and carries a more favorable prognosis.  

Microvascular occlusion syndromes can result in clinical presentations that resemble LIV. Idiopathic thrombocytopenic purpura is a hematologic autoimmune condition resulting in destruction of platelets and subsequent thrombocytopenia. Idiopathic thrombocytopenic purpura can be either primary or secondary to infections, drugs, malignancy, or other autoimmune conditions. Clinically, it presents as mucosal or cutaneous bleeding, epistaxis, hematochezia, or hematuria and can result in substantial hemorrhage. On the skin, it can appear as petechiae and ecchymoses in dependent areas and rarely hemorrhagic bullae of the skin and mucous membranes in cases of severe thrombocytopenia.^11,12 Biopsies of these lesions will show notable extravasation of red blood cells with incipient hemorrhagic bullae formation (Figure 4). Recognition of hemorrhagic bullae as a presentation of idiopathic thrombocytopenic purpura is critical to identifying severe underlying disease.  

Beyond other vasculitides and microvascular occlusion syndromes, vessel-invasive microorganisms can result in similar histopathologic and clinical presentations to LIV. Ecthyma gangrenosum (EG) is a septic vasculitis, often caused by Pseudomonas aeruginosa, usually affecting immunocompromised patients. Ecthyma gangrenosum presents with vesiculobullous lesions with erythematous violaceous borders that develop into hemorrhagic bullae with necrotic centers.¹³ Biopsy of EG will show vascular occlusion and basophilic granular material within or around vessels, suggestive of bacterial sepsis (Figure 5). The detection of an infectious agent on histopathology allows one to easily distinguish between EG and LIV.  

The Diagnosis: Levamisole-Induced Vasculopathy

Biopsy of one of the bullous retiform purpura on the leg (Figure 1) revealed a combined leukocytoclastic vasculitis and thrombotic vasculopathy (quiz images). Periodic acid-Schiff and Gram stains, with adequate controls, were negative for pathogenic fungal and bacterial organisms. Although this reaction pattern has an extensive differential, in this clinical setting with associated cocaine-positive urine toxicologic analysis, perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), and leukopenia, the histopathologic findings were consistent with levamisole-induced vasculopathy (LIV).^1,2 Although not specific, leukocytoclastic vasculitis and thrombotic vasculopathy have been reported as the classic histopathologic findings of LIV. In addition, interstitial and perivascular neovascularization have been reported as a potential histopathologic finding associated with this entity but was not seen in our case.³  

Levamisole is an anthelminthic agent used to adulterate cocaine, a practice first noted in 2003 with increasing incidence.¹ Both levamisole and cocaine stimulate the sympathetic nervous system by increasing dopamine in the euphoric areas of the brain.^1,3 By combining the 2 substances, preparation costs are reduced and stimulant effects are enhanced. It is estimated that 69% to 80% of cocaine in the United States is contaminated with levamisole.^2,4,5 The constellation of findings seen in patients abusing levamisole-contaminated cocaine include agranulocytosis; p-ANCA; and a tender, vasculitic, retiform purpura presentation. The most common sites for the purpura include the cheeks and ears. The purpura can progress to bullous lesions, as seen in our patient, followed by necrosis.^4,6 Recurrent use of levamisole-contaminated cocaine is associated with recurrent agranulocytosis and classic skin findings, which is suggestive of a causal relationship.⁶  

Serologic testing for levamisole exposure presents a challenge. The half-life of levamisole is relatively short (estimated at 5.6 hours) and is found in urine samples approximately 3% of the time.^1,3,6 The volatile diagnostic characteristics of levamisole make concrete laboratory confirmation difficult. Although a skin biopsy can be helpful to rule out other causes of vasculitislike presentations, it is not specific for LIV. Therefore, clinical suspicion for LIV should remain high in patients who present with the cutaneous findings described as well as agranulocytosis, positive p-ANCA, and a history of cocaine use with a skin biopsy showing leukocytoclastic vasculitis and thrombotic vasculopathy.  

The differential diagnosis for LIV with retiform bullous lesions includes several other vasculitides and vesiculobullous diseases. Eosinophilic granulomatosis with polyangiitis (EGPA) is a multisystem vasculitis that is characterized by eosinophilia, asthma, and rhinosinusitis. Eosinophilic granulomatosis with polyangiitis primarily affects small and medium arteries in the skin and respiratory tract and occurs in 3 stages: prodromal, eosinophilic, and vasculitic. These stages are characterized by mild asthma or rhinitis, eosinophilia with multiorgan infiltration, and vasculitis with extravascular granulomatosis, respectively. Diagnosis often is clinical based on these findings and laboratory evaluation. Eosinophilic granulomatosis with polyangiitis presents with positive p-ANCA in 40% to 60% of patients.⁷ The vasculitis stage of EGPA presents with cutaneous findings in 60% of cases, including palpable purpura, infiltrated papules and plaques, urticaria, necrotizing lesions, and rarely vesicles and bullae.⁸ Classic histopathologic features include leukocytoclastic or eosinophilic vasculitis, an eosinophilic infiltrate, granuloma formation, and eosinophilic granule deposition onto collagen fibrils (otherwise known as flame figures)(Figure 2). Biopsy of these lesions with the aforementioned findings, in constellation with the described systemic signs and symptoms, can aid in diagnosis of EGPA.  

Polyarteritis nodosa (PAN) is a vasculitis that can be either multisystem or limited to one organ. Classic PAN affects the small- to medium-sized vessels. When there is multisystem involvement, it most often affects the skin, gastrointestinal tract, and kidneys. It presents with subcutaneous or dermal nodules, necrotic lesions, livedo reticularis, hypertension, abdominal pain, and an acute abdomen.⁹ When PAN is in its limited form, it most commonly occurs in the skin. The cutaneous manifestations of skin-limited PAN are identical to classic PAN, most commonly occurring on the legs and arms and less often on the trunk, head, and neck.¹⁰ To aid in diagnosis, biopsies of cutaneous lesions are beneficial. Dermatopathologic examination of PAN reveals fibrinoid necrosis of small and medium vessels with a perivascular mononuclear inflammatory infiltrate (Figure 3). Cutaneous PAN rarely progresses to multisystem classic PAN and carries a more favorable prognosis.  

Microvascular occlusion syndromes can result in clinical presentations that resemble LIV. Idiopathic thrombocytopenic purpura is a hematologic autoimmune condition resulting in destruction of platelets and subsequent thrombocytopenia. Idiopathic thrombocytopenic purpura can be either primary or secondary to infections, drugs, malignancy, or other autoimmune conditions. Clinically, it presents as mucosal or cutaneous bleeding, epistaxis, hematochezia, or hematuria and can result in substantial hemorrhage. On the skin, it can appear as petechiae and ecchymoses in dependent areas and rarely hemorrhagic bullae of the skin and mucous membranes in cases of severe thrombocytopenia.^11,12 Biopsies of these lesions will show notable extravasation of red blood cells with incipient hemorrhagic bullae formation (Figure 4). Recognition of hemorrhagic bullae as a presentation of idiopathic thrombocytopenic purpura is critical to identifying severe underlying disease.  

Beyond other vasculitides and microvascular occlusion syndromes, vessel-invasive microorganisms can result in similar histopathologic and clinical presentations to LIV. Ecthyma gangrenosum (EG) is a septic vasculitis, often caused by Pseudomonas aeruginosa, usually affecting immunocompromised patients. Ecthyma gangrenosum presents with vesiculobullous lesions with erythematous violaceous borders that develop into hemorrhagic bullae with necrotic centers.¹³ Biopsy of EG will show vascular occlusion and basophilic granular material within or around vessels, suggestive of bacterial sepsis (Figure 5). The detection of an infectious agent on histopathology allows one to easily distinguish between EG and LIV.  

The Diagnosis: Levamisole-Induced Vasculopathy

Biopsy of one of the bullous retiform purpura on the leg (Figure 1) revealed a combined leukocytoclastic vasculitis and thrombotic vasculopathy (quiz images). Periodic acid-Schiff and Gram stains, with adequate controls, were negative for pathogenic fungal and bacterial organisms. Although this reaction pattern has an extensive differential, in this clinical setting with associated cocaine-positive urine toxicologic analysis, perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), and leukopenia, the histopathologic findings were consistent with levamisole-induced vasculopathy (LIV).^1,2 Although not specific, leukocytoclastic vasculitis and thrombotic vasculopathy have been reported as the classic histopathologic findings of LIV. In addition, interstitial and perivascular neovascularization have been reported as a potential histopathologic finding associated with this entity but was not seen in our case.³  

Levamisole is an anthelminthic agent used to adulterate cocaine, a practice first noted in 2003 with increasing incidence.¹ Both levamisole and cocaine stimulate the sympathetic nervous system by increasing dopamine in the euphoric areas of the brain.^1,3 By combining the 2 substances, preparation costs are reduced and stimulant effects are enhanced. It is estimated that 69% to 80% of cocaine in the United States is contaminated with levamisole.^2,4,5 The constellation of findings seen in patients abusing levamisole-contaminated cocaine include agranulocytosis; p-ANCA; and a tender, vasculitic, retiform purpura presentation. The most common sites for the purpura include the cheeks and ears. The purpura can progress to bullous lesions, as seen in our patient, followed by necrosis.^4,6 Recurrent use of levamisole-contaminated cocaine is associated with recurrent agranulocytosis and classic skin findings, which is suggestive of a causal relationship.⁶  

Serologic testing for levamisole exposure presents a challenge. The half-life of levamisole is relatively short (estimated at 5.6 hours) and is found in urine samples approximately 3% of the time.^1,3,6 The volatile diagnostic characteristics of levamisole make concrete laboratory confirmation difficult. Although a skin biopsy can be helpful to rule out other causes of vasculitislike presentations, it is not specific for LIV. Therefore, clinical suspicion for LIV should remain high in patients who present with the cutaneous findings described as well as agranulocytosis, positive p-ANCA, and a history of cocaine use with a skin biopsy showing leukocytoclastic vasculitis and thrombotic vasculopathy.  

The differential diagnosis for LIV with retiform bullous lesions includes several other vasculitides and vesiculobullous diseases. Eosinophilic granulomatosis with polyangiitis (EGPA) is a multisystem vasculitis that is characterized by eosinophilia, asthma, and rhinosinusitis. Eosinophilic granulomatosis with polyangiitis primarily affects small and medium arteries in the skin and respiratory tract and occurs in 3 stages: prodromal, eosinophilic, and vasculitic. These stages are characterized by mild asthma or rhinitis, eosinophilia with multiorgan infiltration, and vasculitis with extravascular granulomatosis, respectively. Diagnosis often is clinical based on these findings and laboratory evaluation. Eosinophilic granulomatosis with polyangiitis presents with positive p-ANCA in 40% to 60% of patients.⁷ The vasculitis stage of EGPA presents with cutaneous findings in 60% of cases, including palpable purpura, infiltrated papules and plaques, urticaria, necrotizing lesions, and rarely vesicles and bullae.⁸ Classic histopathologic features include leukocytoclastic or eosinophilic vasculitis, an eosinophilic infiltrate, granuloma formation, and eosinophilic granule deposition onto collagen fibrils (otherwise known as flame figures)(Figure 2). Biopsy of these lesions with the aforementioned findings, in constellation with the described systemic signs and symptoms, can aid in diagnosis of EGPA.  

Polyarteritis nodosa (PAN) is a vasculitis that can be either multisystem or limited to one organ. Classic PAN affects the small- to medium-sized vessels. When there is multisystem involvement, it most often affects the skin, gastrointestinal tract, and kidneys. It presents with subcutaneous or dermal nodules, necrotic lesions, livedo reticularis, hypertension, abdominal pain, and an acute abdomen.⁹ When PAN is in its limited form, it most commonly occurs in the skin. The cutaneous manifestations of skin-limited PAN are identical to classic PAN, most commonly occurring on the legs and arms and less often on the trunk, head, and neck.¹⁰ To aid in diagnosis, biopsies of cutaneous lesions are beneficial. Dermatopathologic examination of PAN reveals fibrinoid necrosis of small and medium vessels with a perivascular mononuclear inflammatory infiltrate (Figure 3). Cutaneous PAN rarely progresses to multisystem classic PAN and carries a more favorable prognosis.  

Microvascular occlusion syndromes can result in clinical presentations that resemble LIV. Idiopathic thrombocytopenic purpura is a hematologic autoimmune condition resulting in destruction of platelets and subsequent thrombocytopenia. Idiopathic thrombocytopenic purpura can be either primary or secondary to infections, drugs, malignancy, or other autoimmune conditions. Clinically, it presents as mucosal or cutaneous bleeding, epistaxis, hematochezia, or hematuria and can result in substantial hemorrhage. On the skin, it can appear as petechiae and ecchymoses in dependent areas and rarely hemorrhagic bullae of the skin and mucous membranes in cases of severe thrombocytopenia.^11,12 Biopsies of these lesions will show notable extravasation of red blood cells with incipient hemorrhagic bullae formation (Figure 4). Recognition of hemorrhagic bullae as a presentation of idiopathic thrombocytopenic purpura is critical to identifying severe underlying disease.  

Beyond other vasculitides and microvascular occlusion syndromes, vessel-invasive microorganisms can result in similar histopathologic and clinical presentations to LIV. Ecthyma gangrenosum (EG) is a septic vasculitis, often caused by Pseudomonas aeruginosa, usually affecting immunocompromised patients. Ecthyma gangrenosum presents with vesiculobullous lesions with erythematous violaceous borders that develop into hemorrhagic bullae with necrotic centers.¹³ Biopsy of EG will show vascular occlusion and basophilic granular material within or around vessels, suggestive of bacterial sepsis (Figure 5). The detection of an infectious agent on histopathology allows one to easily distinguish between EG and LIV.  

The Diagnosis: Cystic Panfolliculoma 

Panfolliculoma is a rare tumor of follicular origin.¹ Clinical examination can reveal a papule, nodule, or tumor that typically is mistaken for an epidermal inclusion cyst, trichoepithelioma, or basal cell carcinoma (BCC).² As with other benign follicular neoplasms, it often exhibits a protracted growth pattern.^3,4 Most cases reported in the literature have been shown to occur in the head or neck region. One hypothesis is that separation into the various components of the hair follicle occurs at a higher frequency in areas with a higher hair density such as the face and scalp.⁴ The lesion typically presents in patients aged 20 to 70 years, as in our patient, with cases equally distributed among males and females.^4,5 Neill et al1 reported a rare case of cystic panfolliculoma occurring on the right forearm of a 64-year-old woman. 

As its name suggests, panfolliculoma is exceptional in that it displays features of all segments of the hair follicle, including the infundibulum, isthmus, stem, and bulb.⁶ Although not necessary for diagnosis, immunohistochemical staining can be utilized to identify each hair follicle component on histopathologic examination. Panfolliculoma stains positive for 34βE12 and cytokeratin 5/6, highlighting infundibular and isthmus keratinocytes and the outer root sheath, respectively. Additionally, Ber-EP4 labels germinative cells, while CD34 highlights contiguous fibrotic stroma and trichilemmal areas.^3,4 

In our patient, histopathology revealed a cystic structure that was lined by an infundibular epithelium with a prominent granular layer. Solid collections of basaloid germinative cells that demonstrated peripheral palisading were observed (quiz image [top]). Cells with trichohyalin granules, indicative of inner root sheath differentiation, were encased by matrical cells (quiz image [bottom]).  

Historically, panfolliculomas characteristically have been known to reside in the dermis, with only focal connection to the epidermis, if at all present. Nevertheless, Harris et al⁷ detailed 2 cases that displayed predominant epidermal involvement, defined by the term epidermal panfolliculoma. In a study performed by Shan and Guo,² an additional 9 cases (19 panfolliculomas) were found to have similar findings, for which the term superficial panfolliculoma was suggested. In cases that display a primary epidermal component, common mimickers include tumor of the follicular infundibulum and the reactive process of follicular induction.⁷ 

Cystic panfolliculoma is a rare subtype further characterized as a lesion with distinctive features of a panfolliculoma that arises from a cyst wall composed of the follicular infundibulum.^2,6 The origin of cystic panfolliculoma has not been fully elucidated. It has been hypothesized that the formation of such lesions may arise due to epithelial-mesenchymal interactions. One explanation is that basal cells with stem cell capability may progress into hair follicle structures after communication with underlying dermal cells during invagination of the epidermis, while the epithelial cells not in close proximity to dermal cells maintain stem cell capability.⁸ 

The histologic differential diagnosis of cystic panfolliculoma includes dilated pore of Winer, epidermal inclusion cyst, pilar cyst, trichofolliculoma, folliculosebaceous cystic hamartoma, cystic trichoblastoma, and BCC.⁵ Panfolliculoma can mimic both trichoblastoma and trichoepithelioma on a low-power field; however, the latter follicular tumors lack differentiation to the infundibulum, isthmus, outer root sheath, or hair shaft, as in a panfolliculoma.⁴ Trichoblastoma is composed of germinative hair follicle cells, with differentiation limited to the hair germ and papilla (Figure 1).⁹ Panfolliculoma additionally differs from trichoblastoma by having a more prevalent epithelial factor compared to a more pronounced stromal factor in trichoblastoma.¹ The cystic subtype of trichoblastoma differs from cystic panfolliculoma in that the cyst wall develops from the infundibulum only and has germinative cells protruding outwards from the cyst wall.  

Although BCCs may arise in cystic structures, panfolliculomas can be discerned from this entity by their sharp demarcation, lack of peritumoral clefting, and presence of cytokeratin 20-positive Merkel cells.⁵ Unlike panfolliculoma, the tumor islands in BCC commonly display peripheral palisading of nuclei with a surrounding fibromyxoid stroma (Figure 2). Additionally, BCCs can exhibit crowding of nuclei, atypia, and mitoses.⁶ 

Folliculosebaceous cystic hamartomas and cystic panfolliculomas both contain a cystic structure with differentiation of the cyst wall to the hair follicle. However, folliculosebaceous cystic hamartomas are dilated infundibulocystic configurations that contain sebaceous glands emanating from the cyst wall (Figure 3). Kimura et al¹⁰ described defining features of the mesenchymal component of this follicular tumor, including an increase in fibroplasia, vascularity, and adipose tissue. In addition, the epithelial aspect exhibits clefting among the stroma and uninvolved dermis.⁶

Dilated pore of Winer consists of a cystic opening with connection to the epidermis. The cyst wall resembles the follicular infundibulum, and the cavity is filled with lamellar orthokeratosis (Figure 4).^5,11 Epidermal inclusion cysts also contain a cyst wall that resembles the infundibular epithelium, without differentiation to all segments of the hair follicle. They are lined by a stratified squamous epithelium, retain a granular layer, and contain lamellar keratin within the cyst cavity.^5,12 

In summary, panfolliculoma is a rare benign neoplasm that demonstrates differentiation to each component of the hair follicle structure. Our case demonstrates a unique subtype showcasing cystic changes that infrequently has been described in the literature. 

The Diagnosis: Cystic Panfolliculoma 

Panfolliculoma is a rare tumor of follicular origin.¹ Clinical examination can reveal a papule, nodule, or tumor that typically is mistaken for an epidermal inclusion cyst, trichoepithelioma, or basal cell carcinoma (BCC).² As with other benign follicular neoplasms, it often exhibits a protracted growth pattern.^3,4 Most cases reported in the literature have been shown to occur in the head or neck region. One hypothesis is that separation into the various components of the hair follicle occurs at a higher frequency in areas with a higher hair density such as the face and scalp.⁴ The lesion typically presents in patients aged 20 to 70 years, as in our patient, with cases equally distributed among males and females.^4,5 Neill et al1 reported a rare case of cystic panfolliculoma occurring on the right forearm of a 64-year-old woman. 

As its name suggests, panfolliculoma is exceptional in that it displays features of all segments of the hair follicle, including the infundibulum, isthmus, stem, and bulb.⁶ Although not necessary for diagnosis, immunohistochemical staining can be utilized to identify each hair follicle component on histopathologic examination. Panfolliculoma stains positive for 34βE12 and cytokeratin 5/6, highlighting infundibular and isthmus keratinocytes and the outer root sheath, respectively. Additionally, Ber-EP4 labels germinative cells, while CD34 highlights contiguous fibrotic stroma and trichilemmal areas.^3,4 

In our patient, histopathology revealed a cystic structure that was lined by an infundibular epithelium with a prominent granular layer. Solid collections of basaloid germinative cells that demonstrated peripheral palisading were observed (quiz image [top]). Cells with trichohyalin granules, indicative of inner root sheath differentiation, were encased by matrical cells (quiz image [bottom]).  

Historically, panfolliculomas characteristically have been known to reside in the dermis, with only focal connection to the epidermis, if at all present. Nevertheless, Harris et al⁷ detailed 2 cases that displayed predominant epidermal involvement, defined by the term epidermal panfolliculoma. In a study performed by Shan and Guo,² an additional 9 cases (19 panfolliculomas) were found to have similar findings, for which the term superficial panfolliculoma was suggested. In cases that display a primary epidermal component, common mimickers include tumor of the follicular infundibulum and the reactive process of follicular induction.⁷ 

Cystic panfolliculoma is a rare subtype further characterized as a lesion with distinctive features of a panfolliculoma that arises from a cyst wall composed of the follicular infundibulum.^2,6 The origin of cystic panfolliculoma has not been fully elucidated. It has been hypothesized that the formation of such lesions may arise due to epithelial-mesenchymal interactions. One explanation is that basal cells with stem cell capability may progress into hair follicle structures after communication with underlying dermal cells during invagination of the epidermis, while the epithelial cells not in close proximity to dermal cells maintain stem cell capability.⁸ 

The histologic differential diagnosis of cystic panfolliculoma includes dilated pore of Winer, epidermal inclusion cyst, pilar cyst, trichofolliculoma, folliculosebaceous cystic hamartoma, cystic trichoblastoma, and BCC.⁵ Panfolliculoma can mimic both trichoblastoma and trichoepithelioma on a low-power field; however, the latter follicular tumors lack differentiation to the infundibulum, isthmus, outer root sheath, or hair shaft, as in a panfolliculoma.⁴ Trichoblastoma is composed of germinative hair follicle cells, with differentiation limited to the hair germ and papilla (Figure 1).⁹ Panfolliculoma additionally differs from trichoblastoma by having a more prevalent epithelial factor compared to a more pronounced stromal factor in trichoblastoma.¹ The cystic subtype of trichoblastoma differs from cystic panfolliculoma in that the cyst wall develops from the infundibulum only and has germinative cells protruding outwards from the cyst wall.  

Although BCCs may arise in cystic structures, panfolliculomas can be discerned from this entity by their sharp demarcation, lack of peritumoral clefting, and presence of cytokeratin 20-positive Merkel cells.⁵ Unlike panfolliculoma, the tumor islands in BCC commonly display peripheral palisading of nuclei with a surrounding fibromyxoid stroma (Figure 2). Additionally, BCCs can exhibit crowding of nuclei, atypia, and mitoses.⁶ 

Folliculosebaceous cystic hamartomas and cystic panfolliculomas both contain a cystic structure with differentiation of the cyst wall to the hair follicle. However, folliculosebaceous cystic hamartomas are dilated infundibulocystic configurations that contain sebaceous glands emanating from the cyst wall (Figure 3). Kimura et al¹⁰ described defining features of the mesenchymal component of this follicular tumor, including an increase in fibroplasia, vascularity, and adipose tissue. In addition, the epithelial aspect exhibits clefting among the stroma and uninvolved dermis.⁶

Dilated pore of Winer consists of a cystic opening with connection to the epidermis. The cyst wall resembles the follicular infundibulum, and the cavity is filled with lamellar orthokeratosis (Figure 4).^5,11 Epidermal inclusion cysts also contain a cyst wall that resembles the infundibular epithelium, without differentiation to all segments of the hair follicle. They are lined by a stratified squamous epithelium, retain a granular layer, and contain lamellar keratin within the cyst cavity.^5,12 

In summary, panfolliculoma is a rare benign neoplasm that demonstrates differentiation to each component of the hair follicle structure. Our case demonstrates a unique subtype showcasing cystic changes that infrequently has been described in the literature. 

The Diagnosis: Cystic Panfolliculoma 

Panfolliculoma is a rare tumor of follicular origin.¹ Clinical examination can reveal a papule, nodule, or tumor that typically is mistaken for an epidermal inclusion cyst, trichoepithelioma, or basal cell carcinoma (BCC).² As with other benign follicular neoplasms, it often exhibits a protracted growth pattern.^3,4 Most cases reported in the literature have been shown to occur in the head or neck region. One hypothesis is that separation into the various components of the hair follicle occurs at a higher frequency in areas with a higher hair density such as the face and scalp.⁴ The lesion typically presents in patients aged 20 to 70 years, as in our patient, with cases equally distributed among males and females.^4,5 Neill et al1 reported a rare case of cystic panfolliculoma occurring on the right forearm of a 64-year-old woman. 

As its name suggests, panfolliculoma is exceptional in that it displays features of all segments of the hair follicle, including the infundibulum, isthmus, stem, and bulb.⁶ Although not necessary for diagnosis, immunohistochemical staining can be utilized to identify each hair follicle component on histopathologic examination. Panfolliculoma stains positive for 34βE12 and cytokeratin 5/6, highlighting infundibular and isthmus keratinocytes and the outer root sheath, respectively. Additionally, Ber-EP4 labels germinative cells, while CD34 highlights contiguous fibrotic stroma and trichilemmal areas.^3,4 

In our patient, histopathology revealed a cystic structure that was lined by an infundibular epithelium with a prominent granular layer. Solid collections of basaloid germinative cells that demonstrated peripheral palisading were observed (quiz image [top]). Cells with trichohyalin granules, indicative of inner root sheath differentiation, were encased by matrical cells (quiz image [bottom]).  

Historically, panfolliculomas characteristically have been known to reside in the dermis, with only focal connection to the epidermis, if at all present. Nevertheless, Harris et al⁷ detailed 2 cases that displayed predominant epidermal involvement, defined by the term epidermal panfolliculoma. In a study performed by Shan and Guo,² an additional 9 cases (19 panfolliculomas) were found to have similar findings, for which the term superficial panfolliculoma was suggested. In cases that display a primary epidermal component, common mimickers include tumor of the follicular infundibulum and the reactive process of follicular induction.⁷ 

Cystic panfolliculoma is a rare subtype further characterized as a lesion with distinctive features of a panfolliculoma that arises from a cyst wall composed of the follicular infundibulum.^2,6 The origin of cystic panfolliculoma has not been fully elucidated. It has been hypothesized that the formation of such lesions may arise due to epithelial-mesenchymal interactions. One explanation is that basal cells with stem cell capability may progress into hair follicle structures after communication with underlying dermal cells during invagination of the epidermis, while the epithelial cells not in close proximity to dermal cells maintain stem cell capability.⁸ 

The histologic differential diagnosis of cystic panfolliculoma includes dilated pore of Winer, epidermal inclusion cyst, pilar cyst, trichofolliculoma, folliculosebaceous cystic hamartoma, cystic trichoblastoma, and BCC.⁵ Panfolliculoma can mimic both trichoblastoma and trichoepithelioma on a low-power field; however, the latter follicular tumors lack differentiation to the infundibulum, isthmus, outer root sheath, or hair shaft, as in a panfolliculoma.⁴ Trichoblastoma is composed of germinative hair follicle cells, with differentiation limited to the hair germ and papilla (Figure 1).⁹ Panfolliculoma additionally differs from trichoblastoma by having a more prevalent epithelial factor compared to a more pronounced stromal factor in trichoblastoma.¹ The cystic subtype of trichoblastoma differs from cystic panfolliculoma in that the cyst wall develops from the infundibulum only and has germinative cells protruding outwards from the cyst wall.  

Although BCCs may arise in cystic structures, panfolliculomas can be discerned from this entity by their sharp demarcation, lack of peritumoral clefting, and presence of cytokeratin 20-positive Merkel cells.⁵ Unlike panfolliculoma, the tumor islands in BCC commonly display peripheral palisading of nuclei with a surrounding fibromyxoid stroma (Figure 2). Additionally, BCCs can exhibit crowding of nuclei, atypia, and mitoses.⁶ 

Folliculosebaceous cystic hamartomas and cystic panfolliculomas both contain a cystic structure with differentiation of the cyst wall to the hair follicle. However, folliculosebaceous cystic hamartomas are dilated infundibulocystic configurations that contain sebaceous glands emanating from the cyst wall (Figure 3). Kimura et al¹⁰ described defining features of the mesenchymal component of this follicular tumor, including an increase in fibroplasia, vascularity, and adipose tissue. In addition, the epithelial aspect exhibits clefting among the stroma and uninvolved dermis.⁶

Dilated pore of Winer consists of a cystic opening with connection to the epidermis. The cyst wall resembles the follicular infundibulum, and the cavity is filled with lamellar orthokeratosis (Figure 4).^5,11 Epidermal inclusion cysts also contain a cyst wall that resembles the infundibular epithelium, without differentiation to all segments of the hair follicle. They are lined by a stratified squamous epithelium, retain a granular layer, and contain lamellar keratin within the cyst cavity.^5,12 

In summary, panfolliculoma is a rare benign neoplasm that demonstrates differentiation to each component of the hair follicle structure. Our case demonstrates a unique subtype showcasing cystic changes that infrequently has been described in the literature. 

The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Accreditation Council for Graduate Medical Education has established core competencies to serve as a foundation for the training received in a dermatology residency program.¹ Although programs are required to have the same concentrations—patient care, medical knowledge, practice-based learning and improvement, interpersonal and communication skills, professionalism, and systems-based practice—no specific guidelines are in place regarding how each of these competencies should be reached within a training period.² Instead, it remains the responsibility of each program to formulate an individualized curriculum to facilitate proficiency in the multiple areas encompassed by a residency.

In many dermatology residency programs, dermatopathology is a substantial component of educational objectives and the curriculum.¹ Residents may spend as much as 25% of their training on dermatopathology. However, there is great variability among programs in methods of teaching dermatopathology. When Hinshaw³ surveyed 52 of 109 dermatology residency programs, they identified differences in dermatopathology teaching that included, but was not limited to, utilization of problem-based learning (in 40.4% of programs), integration of journal reviews (53.8%), and computer-based learning (19.2%). In addition, differences were identified in the recommended primary textbook and the makeup of faculty who taught dermatopathology.³

Although residency programs vary in their methods of teaching this important component of dermatology, most use a multiheaded microscope in some capacity for didactics or sign-out. For most trainees, the dermatopathology laboratory is a new environment compared to the clinical space that medical students and residents become accustomed to throughout their education, thus creating a knowledge gap for trainees on proper dermatopathology etiquette and universal guidelines.

With medical students, residents, and fellows in mind, we have prepared a basic “dermatopathology etiquette” reference for trainees. Just as there are universal rules in the operating room for surgery (eg, sterile technique), we want to establish a code of conduct at the microscope. We hope that these 10 tips will, first, be useful to those who are unsure how to approach their first experience with dermatopathology and, second, serve as a guideline to aid development of appropriate communication skills and functioning within this novel setting. This list also can serve as a resource for dermatopathology attendings to provide to rotating residents and students.

1. New to pathology? It’s okay to ask. Do not hesitate to ask upper-year residents, fellows, and attendings for instructions on such matters as how to adjust your eyepiece to get the best resolution. 

2. If a slide drops on the floor, do not move! Your first instinct might be to move your chair to look for the dropped slide, but you might roll over it and break it.

3. When the attending is looking through the scope, you look through the scope. Dermatopathology is a visual exercise. Getting in your “optic mileage” is best done under the guidance of an experienced dermatopathologist.

4. Rules regarding food and drink at the microscope vary by pathologist. It’s best to ask what each attending prefers. Safe advice is to avoid foods that make noise, such as chewing gum and chips, and food that has a strong odor, such as microwaved leftovers.

5. Limit use of a laptop, cell phone, and smartwatch. If you think that using any of these is necessary, it generally is best to announce that you are looking up something related to the case and then share your findings (but not the most recent post on your Facebook News Feed).

6. If you notice that something needs correcting on the report, speak up! We are all human; we all make typos. Do not hesitate to mention this as soon as possible, especially before the case is signed out. You will likely be thanked by your attending because it is harder to rectify once the report has been signed out.

7. Small talk often is welcome during large excisions. This is a great time to ask what others are doing next weekend or what happened in clinic earlier that day, or just to tell a good (clean) joke that is making the rounds. Conversely, if the case is complex, it often is best to wait until it is completed before asking questions.

8. When participating in a roundtable diagnosis, you are welcome to directly state the diagnosis for bread-and-butter cases, such as basal cell carcinomas and seborrheic keratoses. It is appropriate to be more descriptive and methodical in more complex cases. When evaluating a rash, give the general inflammatory pattern first. For example, is it spongiotic? Psoriasiform? Interface? Or a mixed pattern?

9. Extra points for identifying special sites! These include mucosal, genital, and acral sites. You might even get bonus points if you can determine something about the patient (child or adult) based on the pathologic features, such as variation in collagen patterns.

10. Whenever you are in doubt, just describe what you see. You can use the traditional top-down approach or start with stating the most evident finding, then proceed to a top-down description. If it is a neoplasm, describe the overall architecture; then, what you see at a cellular level will get you some points as well.

We acknowledge that this list of 10 tips is not comprehensive and might vary by attending and each institution’s distinctive training format. We are hopeful, however, that these 10 points of etiquette can serve as a guideline.

The Accreditation Council for Graduate Medical Education has established core competencies to serve as a foundation for the training received in a dermatology residency program.¹ Although programs are required to have the same concentrations—patient care, medical knowledge, practice-based learning and improvement, interpersonal and communication skills, professionalism, and systems-based practice—no specific guidelines are in place regarding how each of these competencies should be reached within a training period.² Instead, it remains the responsibility of each program to formulate an individualized curriculum to facilitate proficiency in the multiple areas encompassed by a residency.

In many dermatology residency programs, dermatopathology is a substantial component of educational objectives and the curriculum.¹ Residents may spend as much as 25% of their training on dermatopathology. However, there is great variability among programs in methods of teaching dermatopathology. When Hinshaw³ surveyed 52 of 109 dermatology residency programs, they identified differences in dermatopathology teaching that included, but was not limited to, utilization of problem-based learning (in 40.4% of programs), integration of journal reviews (53.8%), and computer-based learning (19.2%). In addition, differences were identified in the recommended primary textbook and the makeup of faculty who taught dermatopathology.³

Although residency programs vary in their methods of teaching this important component of dermatology, most use a multiheaded microscope in some capacity for didactics or sign-out. For most trainees, the dermatopathology laboratory is a new environment compared to the clinical space that medical students and residents become accustomed to throughout their education, thus creating a knowledge gap for trainees on proper dermatopathology etiquette and universal guidelines.

With medical students, residents, and fellows in mind, we have prepared a basic “dermatopathology etiquette” reference for trainees. Just as there are universal rules in the operating room for surgery (eg, sterile technique), we want to establish a code of conduct at the microscope. We hope that these 10 tips will, first, be useful to those who are unsure how to approach their first experience with dermatopathology and, second, serve as a guideline to aid development of appropriate communication skills and functioning within this novel setting. This list also can serve as a resource for dermatopathology attendings to provide to rotating residents and students.

1. New to pathology? It’s okay to ask. Do not hesitate to ask upper-year residents, fellows, and attendings for instructions on such matters as how to adjust your eyepiece to get the best resolution. 

2. If a slide drops on the floor, do not move! Your first instinct might be to move your chair to look for the dropped slide, but you might roll over it and break it.

3. When the attending is looking through the scope, you look through the scope. Dermatopathology is a visual exercise. Getting in your “optic mileage” is best done under the guidance of an experienced dermatopathologist.

4. Rules regarding food and drink at the microscope vary by pathologist. It’s best to ask what each attending prefers. Safe advice is to avoid foods that make noise, such as chewing gum and chips, and food that has a strong odor, such as microwaved leftovers.

5. Limit use of a laptop, cell phone, and smartwatch. If you think that using any of these is necessary, it generally is best to announce that you are looking up something related to the case and then share your findings (but not the most recent post on your Facebook News Feed).

6. If you notice that something needs correcting on the report, speak up! We are all human; we all make typos. Do not hesitate to mention this as soon as possible, especially before the case is signed out. You will likely be thanked by your attending because it is harder to rectify once the report has been signed out.

7. Small talk often is welcome during large excisions. This is a great time to ask what others are doing next weekend or what happened in clinic earlier that day, or just to tell a good (clean) joke that is making the rounds. Conversely, if the case is complex, it often is best to wait until it is completed before asking questions.

8. When participating in a roundtable diagnosis, you are welcome to directly state the diagnosis for bread-and-butter cases, such as basal cell carcinomas and seborrheic keratoses. It is appropriate to be more descriptive and methodical in more complex cases. When evaluating a rash, give the general inflammatory pattern first. For example, is it spongiotic? Psoriasiform? Interface? Or a mixed pattern?

9. Extra points for identifying special sites! These include mucosal, genital, and acral sites. You might even get bonus points if you can determine something about the patient (child or adult) based on the pathologic features, such as variation in collagen patterns.

10. Whenever you are in doubt, just describe what you see. You can use the traditional top-down approach or start with stating the most evident finding, then proceed to a top-down description. If it is a neoplasm, describe the overall architecture; then, what you see at a cellular level will get you some points as well.

We acknowledge that this list of 10 tips is not comprehensive and might vary by attending and each institution’s distinctive training format. We are hopeful, however, that these 10 points of etiquette can serve as a guideline.

The Accreditation Council for Graduate Medical Education has established core competencies to serve as a foundation for the training received in a dermatology residency program.¹ Although programs are required to have the same concentrations—patient care, medical knowledge, practice-based learning and improvement, interpersonal and communication skills, professionalism, and systems-based practice—no specific guidelines are in place regarding how each of these competencies should be reached within a training period.² Instead, it remains the responsibility of each program to formulate an individualized curriculum to facilitate proficiency in the multiple areas encompassed by a residency.

In many dermatology residency programs, dermatopathology is a substantial component of educational objectives and the curriculum.¹ Residents may spend as much as 25% of their training on dermatopathology. However, there is great variability among programs in methods of teaching dermatopathology. When Hinshaw³ surveyed 52 of 109 dermatology residency programs, they identified differences in dermatopathology teaching that included, but was not limited to, utilization of problem-based learning (in 40.4% of programs), integration of journal reviews (53.8%), and computer-based learning (19.2%). In addition, differences were identified in the recommended primary textbook and the makeup of faculty who taught dermatopathology.³

Although residency programs vary in their methods of teaching this important component of dermatology, most use a multiheaded microscope in some capacity for didactics or sign-out. For most trainees, the dermatopathology laboratory is a new environment compared to the clinical space that medical students and residents become accustomed to throughout their education, thus creating a knowledge gap for trainees on proper dermatopathology etiquette and universal guidelines.

With medical students, residents, and fellows in mind, we have prepared a basic “dermatopathology etiquette” reference for trainees. Just as there are universal rules in the operating room for surgery (eg, sterile technique), we want to establish a code of conduct at the microscope. We hope that these 10 tips will, first, be useful to those who are unsure how to approach their first experience with dermatopathology and, second, serve as a guideline to aid development of appropriate communication skills and functioning within this novel setting. This list also can serve as a resource for dermatopathology attendings to provide to rotating residents and students.

1. New to pathology? It’s okay to ask. Do not hesitate to ask upper-year residents, fellows, and attendings for instructions on such matters as how to adjust your eyepiece to get the best resolution. 

2. If a slide drops on the floor, do not move! Your first instinct might be to move your chair to look for the dropped slide, but you might roll over it and break it.

3. When the attending is looking through the scope, you look through the scope. Dermatopathology is a visual exercise. Getting in your “optic mileage” is best done under the guidance of an experienced dermatopathologist.

4. Rules regarding food and drink at the microscope vary by pathologist. It’s best to ask what each attending prefers. Safe advice is to avoid foods that make noise, such as chewing gum and chips, and food that has a strong odor, such as microwaved leftovers.

5. Limit use of a laptop, cell phone, and smartwatch. If you think that using any of these is necessary, it generally is best to announce that you are looking up something related to the case and then share your findings (but not the most recent post on your Facebook News Feed).

6. If you notice that something needs correcting on the report, speak up! We are all human; we all make typos. Do not hesitate to mention this as soon as possible, especially before the case is signed out. You will likely be thanked by your attending because it is harder to rectify once the report has been signed out.

7. Small talk often is welcome during large excisions. This is a great time to ask what others are doing next weekend or what happened in clinic earlier that day, or just to tell a good (clean) joke that is making the rounds. Conversely, if the case is complex, it often is best to wait until it is completed before asking questions.

8. When participating in a roundtable diagnosis, you are welcome to directly state the diagnosis for bread-and-butter cases, such as basal cell carcinomas and seborrheic keratoses. It is appropriate to be more descriptive and methodical in more complex cases. When evaluating a rash, give the general inflammatory pattern first. For example, is it spongiotic? Psoriasiform? Interface? Or a mixed pattern?

9. Extra points for identifying special sites! These include mucosal, genital, and acral sites. You might even get bonus points if you can determine something about the patient (child or adult) based on the pathologic features, such as variation in collagen patterns.

10. Whenever you are in doubt, just describe what you see. You can use the traditional top-down approach or start with stating the most evident finding, then proceed to a top-down description. If it is a neoplasm, describe the overall architecture; then, what you see at a cellular level will get you some points as well.

We acknowledge that this list of 10 tips is not comprehensive and might vary by attending and each institution’s distinctive training format. We are hopeful, however, that these 10 points of etiquette can serve as a guideline.