Cutis

The American Contact Dermatitis Society (ACDS) selected sulfites as the 2024 Allergen of the Year.¹ Due to their preservative and antioxidant properties, sulfites are prevalent in a variety of foods, beverages, medications, and personal care products; however, sulfites also have been implicated as a potential contact allergen. In this article, we review common sources of sulfite exposure, clinical manifestations of allergic contact dermatitis (ACD) to sulfites, and patch testing considerations for this emerging allergen.

What Are Sulfites?

Sulfiting agents are compounds that contain the sulfite ion SO₃^2-, including sulfur dioxide, sodium disulfite (sodium metabisulfite), and potassium metabisulfite.² Sulfites occur naturally in the environment and commonly are used as preservatives, antibrowning agents, and antioxidants in various foods, beverages, medications, cosmetics, and skin care products. As antibrowning agents and antioxidants, sulfites help maintain the natural appearance of foods and other products and prevent premature spoiling by inactivating oxidative enzymes.³ It should be noted that sulfites and sulfates are distinct and unrelated compounds that do not cross-react.¹

Common Sources of Sulfite Exposure

From a morning glass of juice to an evening shower, in the pharmacy and at the hair salon, sulfite exposure is ubiquitous in most daily routines. Sulfites are present in many foods and beverages, either as a byproduct of natural fermentation or as an additive to prevent spoiling and color change. The Table provides examples of foods with high sulfite content.^1,4-6 In particular, dried fruit, bottled lemon juice, wine, grape juice, sauerkraut juice, and pickled onions have high sulfite content.

Topical medications and personal care products represent other potential sources of sulfite exposure. A number of reports have shown that sulfites may be included in topical steroids,⁷ antibiotics,⁸ antifungals,⁹ hemorrhoidal preparations,¹⁰ local anesthetics,¹¹ and urinary catheterization gel,¹² highlighting their many potential applications. In addition, a comprehensive ingredient analysis of 264 ophthalmic medications found that 3.8% of the products contained sodium disulfite.¹³ Sulfites may be found in personal care products, including facial and hand cleansers, shampoos, moisturizers, and toothpastes. Hair dyes also commonly contain sulfites,⁷ which are listed in as many as 90% of hair dye kits in the ACDS Contact Allergen Management Program database.¹

Occupational exposures also are widespread, as sulfites are extensively utilized across diverse industries such as pharmaceuticals, health care, leather manufacturing, mineral extraction, food preparation, chemical manufacturing, textiles, alcohol brewing, and wine production.¹

Sulfites also are used in the rubber industry—­particularly in gloves—due to their anticoagulant and preservative properties.⁴ This is relevant to health care providers, who may use dozens of disposable gloves in a single day. In an experimental pilot study, ­researchers detected sulfites in 83% (5/6) of natural rubber latex gloves, 96% (23/24) of synthetic (nitrile) gloves, and 0% (0/5) of polyvinyl chloride gloves.¹⁴ While this study was limited to a small sample size, it demonstrates the common use of sulfites in certain rubber gloves and encourages future studies to determine whether there is a quantitative threshold to elicit allergic reactions.

Sulfite Allergy

In 1968, an early case report of ACD to sulfites was published involving a pharmaceutical worker who developed hand eczema after working at a factory for 3 months and had a positive patch test to potassium metabisulfite.¹⁵ There have been other cases published in the literature since then, including localized ACD as well as less common cases of systemic contact dermatitis following oral, injectable, and rectal sulfite exposures.¹⁶

The North American Contact Dermatitis Group found that, among 132 (2.7%) of 4885 patients with positive patch tests to sodium disulfite from 2017 to 2018, the most commonly involved body sites were the face (28.8%) and hands (20.5%) followed by a scattered/generalized distribution (13.6%). Involvement of the face and hands may correlate with the most frequent sources of exposure that were identified, including personal care products (particularly hair dyes)(18.9%), medications (9.1%), and foods (7.6%).¹⁷ A multicenter analysis of patch test results from Germany, Austria, and Switzerland from 1999 to 2013 showed that 357 (2.9%) of 12,156 patients had positive reactions to sodium disulfite, with the most commonly identified exposure sources being topical pharmaceutical agents (59.3%); cosmetics, creams, and sunscreens (13.6%); and systemic drugs (6.8%).¹⁸ However, it is not always possible to determine the clinical relevance of a positive patch test to sulfites.¹

Other than the face and hands, there have been other unexpected anatomic locations for sulfite ACD (eg, the lower back), and systemic contact dermatitis has manifested with widespread rashes due to oral, rectal, and parenteral exposure.^4,16,19 There is no definitive link between sulfite contact allergy and patient sex, but there seems to be a higher prevalence in patients older than 40 years, perhaps related to overall lifetime exposure.¹

Immediate hypersensitivity reactions to sulfites also have been reported, including urticaria, angioedema, and anaphylaxis.⁴ Due to multiple cases of severe dermatologic and respiratory reactions to food products containing sulfites,²⁰ the US Food and Drug Administration prohibited their use in fresh fruit and vegetables as antibrowning agents in 1986 and required labels on packaged foods that contained sulfites at more than 10 parts per million.²¹ However, food and drinks produced in restaurants, bakeries, and cafes as well as those that are distributed directly to consumers from the preparation site are exempt from these rules.¹⁷

In addition, consuming high amounts of dietary sulfites has been linked to headaches through unclear (ie, not necessarily allergic) mechanisms.^4,22 One study found that wine with a higher sulfite concentration was associated with increased risk for headaches in participants who had a history of headaches related to wine consumption.²²

Patch Testing to Sulfites

The North American Contact Dermatitis Group has tested sodium disulfite since 2017 and found an increased frequency of positive patch tests from 2.7% (N=4885) in 2017 and 2018¹⁷ to 3.3% (N=4115) in 2019 and 2020²³ among patients referred for testing. Similarly, patch testing to sodium disulfite in nearly 40,000 patients in 9 European countries showed a pooled prevalence of reactions of 3.1%.¹⁷ However, this contact allergy may go unrecognized, as sulfites are not included in common patch test series, including the thin-layer rapid use epicutaneous test and the ACDS Core Allergen Series.^24,25 The relatively high patch test positivity to sulfites along with the prevalence of daily exposures supports the addition of sulfites to more patch test screening series.

The recommended patch test concentration for sodium disulfite is 1% in petrolatum.⁵ Testing in aqueous solutions is not recommended because they can cause sulfites to break down, potentially producing false-positive or irritant patch test reactions.^7,26,27

Recommendations for Patients With Sulfite Allergies

Individuals with contact allergies to sulfites should be counseled on exposure sources and should be given resources providing a list of safe products, such as the ACDS Contact Allergen Management Program (https://www.acdscamp.org/login) or SkinSAFE ­(https://www.skinsafeproducts.com/). Prescribers should be cognizant of sulfites that are present in prescription medications. Just because a patient has a positive patch test to sulfites does not automatically imply that they will need to modify their diet to avoid sulfite-containing foods; in the absence of cheilitis or a distribution suggestive of systemic contact dermatitis (eg, vesicular hand/foot dermatitis, intertriginous eruptions), this step may be unnecessary. On the other hand, individuals who have experienced immediate hypersensitivity reactions to sulfites should avoid sulfite-containing foods and carry an epinephrine autoinjector.

Final Interpretation

Sulfites are ubiquitous compounds found in various foods, beverages, medications, and personal care products in addition to a range of occupational exposures. The face and hands are the most common sites of sulfite ACD. Despite patch test positivity in as many as 3% of tested patients,^17,23 sulfite allergy may be missed due to lack of routine testing on standard screening series.

The American Contact Dermatitis Society (ACDS) selected sulfites as the 2024 Allergen of the Year.¹ Due to their preservative and antioxidant properties, sulfites are prevalent in a variety of foods, beverages, medications, and personal care products; however, sulfites also have been implicated as a potential contact allergen. In this article, we review common sources of sulfite exposure, clinical manifestations of allergic contact dermatitis (ACD) to sulfites, and patch testing considerations for this emerging allergen.

What Are Sulfites?

Sulfiting agents are compounds that contain the sulfite ion SO₃^2-, including sulfur dioxide, sodium disulfite (sodium metabisulfite), and potassium metabisulfite.² Sulfites occur naturally in the environment and commonly are used as preservatives, antibrowning agents, and antioxidants in various foods, beverages, medications, cosmetics, and skin care products. As antibrowning agents and antioxidants, sulfites help maintain the natural appearance of foods and other products and prevent premature spoiling by inactivating oxidative enzymes.³ It should be noted that sulfites and sulfates are distinct and unrelated compounds that do not cross-react.¹

Common Sources of Sulfite Exposure

From a morning glass of juice to an evening shower, in the pharmacy and at the hair salon, sulfite exposure is ubiquitous in most daily routines. Sulfites are present in many foods and beverages, either as a byproduct of natural fermentation or as an additive to prevent spoiling and color change. The Table provides examples of foods with high sulfite content.^1,4-6 In particular, dried fruit, bottled lemon juice, wine, grape juice, sauerkraut juice, and pickled onions have high sulfite content.

Topical medications and personal care products represent other potential sources of sulfite exposure. A number of reports have shown that sulfites may be included in topical steroids,⁷ antibiotics,⁸ antifungals,⁹ hemorrhoidal preparations,¹⁰ local anesthetics,¹¹ and urinary catheterization gel,¹² highlighting their many potential applications. In addition, a comprehensive ingredient analysis of 264 ophthalmic medications found that 3.8% of the products contained sodium disulfite.¹³ Sulfites may be found in personal care products, including facial and hand cleansers, shampoos, moisturizers, and toothpastes. Hair dyes also commonly contain sulfites,⁷ which are listed in as many as 90% of hair dye kits in the ACDS Contact Allergen Management Program database.¹

Occupational exposures also are widespread, as sulfites are extensively utilized across diverse industries such as pharmaceuticals, health care, leather manufacturing, mineral extraction, food preparation, chemical manufacturing, textiles, alcohol brewing, and wine production.¹

Sulfites also are used in the rubber industry—­particularly in gloves—due to their anticoagulant and preservative properties.⁴ This is relevant to health care providers, who may use dozens of disposable gloves in a single day. In an experimental pilot study, ­researchers detected sulfites in 83% (5/6) of natural rubber latex gloves, 96% (23/24) of synthetic (nitrile) gloves, and 0% (0/5) of polyvinyl chloride gloves.¹⁴ While this study was limited to a small sample size, it demonstrates the common use of sulfites in certain rubber gloves and encourages future studies to determine whether there is a quantitative threshold to elicit allergic reactions.

Sulfite Allergy

In 1968, an early case report of ACD to sulfites was published involving a pharmaceutical worker who developed hand eczema after working at a factory for 3 months and had a positive patch test to potassium metabisulfite.¹⁵ There have been other cases published in the literature since then, including localized ACD as well as less common cases of systemic contact dermatitis following oral, injectable, and rectal sulfite exposures.¹⁶

The North American Contact Dermatitis Group found that, among 132 (2.7%) of 4885 patients with positive patch tests to sodium disulfite from 2017 to 2018, the most commonly involved body sites were the face (28.8%) and hands (20.5%) followed by a scattered/generalized distribution (13.6%). Involvement of the face and hands may correlate with the most frequent sources of exposure that were identified, including personal care products (particularly hair dyes)(18.9%), medications (9.1%), and foods (7.6%).¹⁷ A multicenter analysis of patch test results from Germany, Austria, and Switzerland from 1999 to 2013 showed that 357 (2.9%) of 12,156 patients had positive reactions to sodium disulfite, with the most commonly identified exposure sources being topical pharmaceutical agents (59.3%); cosmetics, creams, and sunscreens (13.6%); and systemic drugs (6.8%).¹⁸ However, it is not always possible to determine the clinical relevance of a positive patch test to sulfites.¹

Other than the face and hands, there have been other unexpected anatomic locations for sulfite ACD (eg, the lower back), and systemic contact dermatitis has manifested with widespread rashes due to oral, rectal, and parenteral exposure.^4,16,19 There is no definitive link between sulfite contact allergy and patient sex, but there seems to be a higher prevalence in patients older than 40 years, perhaps related to overall lifetime exposure.¹

Immediate hypersensitivity reactions to sulfites also have been reported, including urticaria, angioedema, and anaphylaxis.⁴ Due to multiple cases of severe dermatologic and respiratory reactions to food products containing sulfites,²⁰ the US Food and Drug Administration prohibited their use in fresh fruit and vegetables as antibrowning agents in 1986 and required labels on packaged foods that contained sulfites at more than 10 parts per million.²¹ However, food and drinks produced in restaurants, bakeries, and cafes as well as those that are distributed directly to consumers from the preparation site are exempt from these rules.¹⁷

In addition, consuming high amounts of dietary sulfites has been linked to headaches through unclear (ie, not necessarily allergic) mechanisms.^4,22 One study found that wine with a higher sulfite concentration was associated with increased risk for headaches in participants who had a history of headaches related to wine consumption.²²

Patch Testing to Sulfites

The North American Contact Dermatitis Group has tested sodium disulfite since 2017 and found an increased frequency of positive patch tests from 2.7% (N=4885) in 2017 and 2018¹⁷ to 3.3% (N=4115) in 2019 and 2020²³ among patients referred for testing. Similarly, patch testing to sodium disulfite in nearly 40,000 patients in 9 European countries showed a pooled prevalence of reactions of 3.1%.¹⁷ However, this contact allergy may go unrecognized, as sulfites are not included in common patch test series, including the thin-layer rapid use epicutaneous test and the ACDS Core Allergen Series.^24,25 The relatively high patch test positivity to sulfites along with the prevalence of daily exposures supports the addition of sulfites to more patch test screening series.

The recommended patch test concentration for sodium disulfite is 1% in petrolatum.⁵ Testing in aqueous solutions is not recommended because they can cause sulfites to break down, potentially producing false-positive or irritant patch test reactions.^7,26,27

Recommendations for Patients With Sulfite Allergies

Individuals with contact allergies to sulfites should be counseled on exposure sources and should be given resources providing a list of safe products, such as the ACDS Contact Allergen Management Program (https://www.acdscamp.org/login) or SkinSAFE ­(https://www.skinsafeproducts.com/). Prescribers should be cognizant of sulfites that are present in prescription medications. Just because a patient has a positive patch test to sulfites does not automatically imply that they will need to modify their diet to avoid sulfite-containing foods; in the absence of cheilitis or a distribution suggestive of systemic contact dermatitis (eg, vesicular hand/foot dermatitis, intertriginous eruptions), this step may be unnecessary. On the other hand, individuals who have experienced immediate hypersensitivity reactions to sulfites should avoid sulfite-containing foods and carry an epinephrine autoinjector.

Final Interpretation

Sulfites are ubiquitous compounds found in various foods, beverages, medications, and personal care products in addition to a range of occupational exposures. The face and hands are the most common sites of sulfite ACD. Despite patch test positivity in as many as 3% of tested patients,^17,23 sulfite allergy may be missed due to lack of routine testing on standard screening series.

The American Contact Dermatitis Society (ACDS) selected sulfites as the 2024 Allergen of the Year.¹ Due to their preservative and antioxidant properties, sulfites are prevalent in a variety of foods, beverages, medications, and personal care products; however, sulfites also have been implicated as a potential contact allergen. In this article, we review common sources of sulfite exposure, clinical manifestations of allergic contact dermatitis (ACD) to sulfites, and patch testing considerations for this emerging allergen.

What Are Sulfites?

Sulfiting agents are compounds that contain the sulfite ion SO₃^2-, including sulfur dioxide, sodium disulfite (sodium metabisulfite), and potassium metabisulfite.² Sulfites occur naturally in the environment and commonly are used as preservatives, antibrowning agents, and antioxidants in various foods, beverages, medications, cosmetics, and skin care products. As antibrowning agents and antioxidants, sulfites help maintain the natural appearance of foods and other products and prevent premature spoiling by inactivating oxidative enzymes.³ It should be noted that sulfites and sulfates are distinct and unrelated compounds that do not cross-react.¹

Common Sources of Sulfite Exposure

From a morning glass of juice to an evening shower, in the pharmacy and at the hair salon, sulfite exposure is ubiquitous in most daily routines. Sulfites are present in many foods and beverages, either as a byproduct of natural fermentation or as an additive to prevent spoiling and color change. The Table provides examples of foods with high sulfite content.^1,4-6 In particular, dried fruit, bottled lemon juice, wine, grape juice, sauerkraut juice, and pickled onions have high sulfite content.

Topical medications and personal care products represent other potential sources of sulfite exposure. A number of reports have shown that sulfites may be included in topical steroids,⁷ antibiotics,⁸ antifungals,⁹ hemorrhoidal preparations,¹⁰ local anesthetics,¹¹ and urinary catheterization gel,¹² highlighting their many potential applications. In addition, a comprehensive ingredient analysis of 264 ophthalmic medications found that 3.8% of the products contained sodium disulfite.¹³ Sulfites may be found in personal care products, including facial and hand cleansers, shampoos, moisturizers, and toothpastes. Hair dyes also commonly contain sulfites,⁷ which are listed in as many as 90% of hair dye kits in the ACDS Contact Allergen Management Program database.¹

Occupational exposures also are widespread, as sulfites are extensively utilized across diverse industries such as pharmaceuticals, health care, leather manufacturing, mineral extraction, food preparation, chemical manufacturing, textiles, alcohol brewing, and wine production.¹

Sulfites also are used in the rubber industry—­particularly in gloves—due to their anticoagulant and preservative properties.⁴ This is relevant to health care providers, who may use dozens of disposable gloves in a single day. In an experimental pilot study, ­researchers detected sulfites in 83% (5/6) of natural rubber latex gloves, 96% (23/24) of synthetic (nitrile) gloves, and 0% (0/5) of polyvinyl chloride gloves.¹⁴ While this study was limited to a small sample size, it demonstrates the common use of sulfites in certain rubber gloves and encourages future studies to determine whether there is a quantitative threshold to elicit allergic reactions.

Sulfite Allergy

In 1968, an early case report of ACD to sulfites was published involving a pharmaceutical worker who developed hand eczema after working at a factory for 3 months and had a positive patch test to potassium metabisulfite.¹⁵ There have been other cases published in the literature since then, including localized ACD as well as less common cases of systemic contact dermatitis following oral, injectable, and rectal sulfite exposures.¹⁶

The North American Contact Dermatitis Group found that, among 132 (2.7%) of 4885 patients with positive patch tests to sodium disulfite from 2017 to 2018, the most commonly involved body sites were the face (28.8%) and hands (20.5%) followed by a scattered/generalized distribution (13.6%). Involvement of the face and hands may correlate with the most frequent sources of exposure that were identified, including personal care products (particularly hair dyes)(18.9%), medications (9.1%), and foods (7.6%).¹⁷ A multicenter analysis of patch test results from Germany, Austria, and Switzerland from 1999 to 2013 showed that 357 (2.9%) of 12,156 patients had positive reactions to sodium disulfite, with the most commonly identified exposure sources being topical pharmaceutical agents (59.3%); cosmetics, creams, and sunscreens (13.6%); and systemic drugs (6.8%).¹⁸ However, it is not always possible to determine the clinical relevance of a positive patch test to sulfites.¹

Other than the face and hands, there have been other unexpected anatomic locations for sulfite ACD (eg, the lower back), and systemic contact dermatitis has manifested with widespread rashes due to oral, rectal, and parenteral exposure.^4,16,19 There is no definitive link between sulfite contact allergy and patient sex, but there seems to be a higher prevalence in patients older than 40 years, perhaps related to overall lifetime exposure.¹

Immediate hypersensitivity reactions to sulfites also have been reported, including urticaria, angioedema, and anaphylaxis.⁴ Due to multiple cases of severe dermatologic and respiratory reactions to food products containing sulfites,²⁰ the US Food and Drug Administration prohibited their use in fresh fruit and vegetables as antibrowning agents in 1986 and required labels on packaged foods that contained sulfites at more than 10 parts per million.²¹ However, food and drinks produced in restaurants, bakeries, and cafes as well as those that are distributed directly to consumers from the preparation site are exempt from these rules.¹⁷

In addition, consuming high amounts of dietary sulfites has been linked to headaches through unclear (ie, not necessarily allergic) mechanisms.^4,22 One study found that wine with a higher sulfite concentration was associated with increased risk for headaches in participants who had a history of headaches related to wine consumption.²²

Patch Testing to Sulfites

The North American Contact Dermatitis Group has tested sodium disulfite since 2017 and found an increased frequency of positive patch tests from 2.7% (N=4885) in 2017 and 2018¹⁷ to 3.3% (N=4115) in 2019 and 2020²³ among patients referred for testing. Similarly, patch testing to sodium disulfite in nearly 40,000 patients in 9 European countries showed a pooled prevalence of reactions of 3.1%.¹⁷ However, this contact allergy may go unrecognized, as sulfites are not included in common patch test series, including the thin-layer rapid use epicutaneous test and the ACDS Core Allergen Series.^24,25 The relatively high patch test positivity to sulfites along with the prevalence of daily exposures supports the addition of sulfites to more patch test screening series.

The recommended patch test concentration for sodium disulfite is 1% in petrolatum.⁵ Testing in aqueous solutions is not recommended because they can cause sulfites to break down, potentially producing false-positive or irritant patch test reactions.^7,26,27

Recommendations for Patients With Sulfite Allergies

Individuals with contact allergies to sulfites should be counseled on exposure sources and should be given resources providing a list of safe products, such as the ACDS Contact Allergen Management Program (https://www.acdscamp.org/login) or SkinSAFE ­(https://www.skinsafeproducts.com/). Prescribers should be cognizant of sulfites that are present in prescription medications. Just because a patient has a positive patch test to sulfites does not automatically imply that they will need to modify their diet to avoid sulfite-containing foods; in the absence of cheilitis or a distribution suggestive of systemic contact dermatitis (eg, vesicular hand/foot dermatitis, intertriginous eruptions), this step may be unnecessary. On the other hand, individuals who have experienced immediate hypersensitivity reactions to sulfites should avoid sulfite-containing foods and carry an epinephrine autoinjector.

Final Interpretation

Sulfites are ubiquitous compounds found in various foods, beverages, medications, and personal care products in addition to a range of occupational exposures. The face and hands are the most common sites of sulfite ACD. Despite patch test positivity in as many as 3% of tested patients,^17,23 sulfite allergy may be missed due to lack of routine testing on standard screening series.

THE DIAGNOSIS: Habit-Tic Deformity

Habit-tic deformity is a cause of nail dystrophy that commonly arises in children and adults due to subconscious repetitive and self-injurious manipulation of the nail bed or cuticle, which ultimately damages the nail matrix.^1,2 It can be considered a variant of onychotillomania.¹

Characteristic features of habit-tic deformity include a longitudinal depression on the central nail plate with transverse ridges,¹ which can be more prominent on the dominant hand.³ Patients typically note a long duration of nail deformity, often without insight into its etiology.² Diagnosis relies on careful assessment of the clinical presentation and the patient’s history to rule out other differential diagnoses. Based on our patient’s clinical presentation and history, we excluded wart, squamous cell carcinoma, eczema, psoriasis, lichen planus, autoimmune connective tissue disease, onychomycosis, paronychia, pincer nail deformity, and Beau line as potential diagnoses. Biopsy also can be performed to exclude these diagnoses from the differential if the cause is unclear following clinical examination.

Treatment for habit-tic deformity involves identifying and addressing the underlying habit. Barrier methods such as bandages and cyanoacrylate adhesives that prevent further manipulation of the nail matrix are effective treatments for habit-tic deformity.² A multidisciplinary approach with psychiatry may be optimal to identify underlying psychological comorbidities and break the habit through behavior interventions and medications.⁴ Nail dystrophy generally improves once the habit is disrupted; however, a younger age of onset may carry a worse prognosis.³ Patients should be counseled that the affected nail may never grow normally.

Our patient was advised to use fluocinonide ointment 0.05% to reduce inflammation of the proximal nail fold and to cover the thumbnail with a bandage to prevent picking. He also was counseled that the nail may show ongoing abnormal growth. Minimal improvement was noted after 6 months.

THE DIAGNOSIS: Habit-Tic Deformity

Habit-tic deformity is a cause of nail dystrophy that commonly arises in children and adults due to subconscious repetitive and self-injurious manipulation of the nail bed or cuticle, which ultimately damages the nail matrix.^1,2 It can be considered a variant of onychotillomania.¹

Characteristic features of habit-tic deformity include a longitudinal depression on the central nail plate with transverse ridges,¹ which can be more prominent on the dominant hand.³ Patients typically note a long duration of nail deformity, often without insight into its etiology.² Diagnosis relies on careful assessment of the clinical presentation and the patient’s history to rule out other differential diagnoses. Based on our patient’s clinical presentation and history, we excluded wart, squamous cell carcinoma, eczema, psoriasis, lichen planus, autoimmune connective tissue disease, onychomycosis, paronychia, pincer nail deformity, and Beau line as potential diagnoses. Biopsy also can be performed to exclude these diagnoses from the differential if the cause is unclear following clinical examination.

Treatment for habit-tic deformity involves identifying and addressing the underlying habit. Barrier methods such as bandages and cyanoacrylate adhesives that prevent further manipulation of the nail matrix are effective treatments for habit-tic deformity.² A multidisciplinary approach with psychiatry may be optimal to identify underlying psychological comorbidities and break the habit through behavior interventions and medications.⁴ Nail dystrophy generally improves once the habit is disrupted; however, a younger age of onset may carry a worse prognosis.³ Patients should be counseled that the affected nail may never grow normally.

Our patient was advised to use fluocinonide ointment 0.05% to reduce inflammation of the proximal nail fold and to cover the thumbnail with a bandage to prevent picking. He also was counseled that the nail may show ongoing abnormal growth. Minimal improvement was noted after 6 months.

THE DIAGNOSIS: Habit-Tic Deformity

Habit-tic deformity is a cause of nail dystrophy that commonly arises in children and adults due to subconscious repetitive and self-injurious manipulation of the nail bed or cuticle, which ultimately damages the nail matrix.^1,2 It can be considered a variant of onychotillomania.¹

Characteristic features of habit-tic deformity include a longitudinal depression on the central nail plate with transverse ridges,¹ which can be more prominent on the dominant hand.³ Patients typically note a long duration of nail deformity, often without insight into its etiology.² Diagnosis relies on careful assessment of the clinical presentation and the patient’s history to rule out other differential diagnoses. Based on our patient’s clinical presentation and history, we excluded wart, squamous cell carcinoma, eczema, psoriasis, lichen planus, autoimmune connective tissue disease, onychomycosis, paronychia, pincer nail deformity, and Beau line as potential diagnoses. Biopsy also can be performed to exclude these diagnoses from the differential if the cause is unclear following clinical examination.

Treatment for habit-tic deformity involves identifying and addressing the underlying habit. Barrier methods such as bandages and cyanoacrylate adhesives that prevent further manipulation of the nail matrix are effective treatments for habit-tic deformity.² A multidisciplinary approach with psychiatry may be optimal to identify underlying psychological comorbidities and break the habit through behavior interventions and medications.⁴ Nail dystrophy generally improves once the habit is disrupted; however, a younger age of onset may carry a worse prognosis.³ Patients should be counseled that the affected nail may never grow normally.

Our patient was advised to use fluocinonide ointment 0.05% to reduce inflammation of the proximal nail fold and to cover the thumbnail with a bandage to prevent picking. He also was counseled that the nail may show ongoing abnormal growth. Minimal improvement was noted after 6 months.

To the Editor:

Lichenoid drug eruptions are lichen planus–like hypersensitivity reactions induced by medications. These reactions are rare but cause irritation to the skin, as extreme pruritus is common. One review of 300 consecutive cases of drug eruptions submitted to dermatopathology revealed that 12% of cases were classified as lichenoid drug reactions.¹ Lichenoid dermatitis is characterized by extremely pruritic, scaly, eczematous or psoriasiform papules, often along the extensor surfaces and trunk.² The pruritic nature of the rash can negatively impact quality of life. Treatment typically involves discontinuation of the offending medication, although complete resolution can take months, even after the drug is stopped. Although there have been some data suggesting that topical and/or oral corticosteroids can help with resolution, the rash can persist even with steroid treatment.²

The histopathologic findings of lichenoid drug eruptions show lichen planus–like changes such as hyperkeratosis, irregular acanthosis, and lichenoid interface dermatitis. Accordingly, idiopathic lichen planus is an important differential diagnosis for lichenoid drug eruptions; however, compared to idiopathic lichen planus, lichenoid drug eruptions are more likely to be associated with eosinophils and parakeratosis.^1,3 In some cases, the histopathologic distinction between the 2 conditions is impossible, and clinical history needs to be considered to make a diagnosis.¹ Drugs known to cause lichenoid drug reactions more commonly include angiotensin-converting enzyme inhibitors, beta blockers, thiazides, gold, penicillamine, and antimalarials.² Lichenoid drug eruptions also have been documented in patients taking the second-generation nonsteroidal androgen receptor antagonist enzalutamide, which is used for the treatment of prostate cancer.⁴ More recently, the newer second-generation nonsteroidal androgen receptor antagonist apalutamide has been implicated in several cases of lichenoid drug eruptions.^5,6

We present a case of an apalutamide-induced lichenoid drug eruption that was resistant to dose reduction and required discontinuation of treatment due to the negative impact on the patient’s quality of life. Once the rash resolved, the patient transitioned to enzalutamide without any adverse events (AEs).

A 72-year-old man with a history of metastatic prostate cancer (stage IVB) presented to the dermatology clinic with a 4-month history of a dry itchy rash on the face, chest, back, and legs that had developed 2 to 3 months after oncology started him on apalutamide. The patient initially received apalutamide 240 mg/d, which was reduced by his oncologist 3 months later to 180 mg/d following the appearance of the rash. Then apalutamide was held as he awaited improvement of the rash.

One week after the apalutamide was held, the patient presented to dermatology. He reported that he had tried over-the-counter ammonium lactate 12% lotion twice daily when the rash first developed without improvement. When the apalutamide was held, oncology prescribed mupirocin ointment 2% 3 times daily which yielded minimal relief. On physical examination, widespread lichenified papules and plaques were noted on the face, chest, back, and legs (Figure 1). Dermatology initially prescribed triamcinolone ointment 0.1% twice daily. A 4-mm punch biopsy specimen of the upper back revealed a lichenoid interface dermatitis with numerous eosinophils compatible with a lichenoid hypersensitivity reaction (Figure 2). Considering the clinical and histologic findings, a diagnosis of lichenoid drug eruption secondary to apalutamide treatment was made.

To the Editor:

Lichenoid drug eruptions are lichen planus–like hypersensitivity reactions induced by medications. These reactions are rare but cause irritation to the skin, as extreme pruritus is common. One review of 300 consecutive cases of drug eruptions submitted to dermatopathology revealed that 12% of cases were classified as lichenoid drug reactions.¹ Lichenoid dermatitis is characterized by extremely pruritic, scaly, eczematous or psoriasiform papules, often along the extensor surfaces and trunk.² The pruritic nature of the rash can negatively impact quality of life. Treatment typically involves discontinuation of the offending medication, although complete resolution can take months, even after the drug is stopped. Although there have been some data suggesting that topical and/or oral corticosteroids can help with resolution, the rash can persist even with steroid treatment.²

The histopathologic findings of lichenoid drug eruptions show lichen planus–like changes such as hyperkeratosis, irregular acanthosis, and lichenoid interface dermatitis. Accordingly, idiopathic lichen planus is an important differential diagnosis for lichenoid drug eruptions; however, compared to idiopathic lichen planus, lichenoid drug eruptions are more likely to be associated with eosinophils and parakeratosis.^1,3 In some cases, the histopathologic distinction between the 2 conditions is impossible, and clinical history needs to be considered to make a diagnosis.¹ Drugs known to cause lichenoid drug reactions more commonly include angiotensin-converting enzyme inhibitors, beta blockers, thiazides, gold, penicillamine, and antimalarials.² Lichenoid drug eruptions also have been documented in patients taking the second-generation nonsteroidal androgen receptor antagonist enzalutamide, which is used for the treatment of prostate cancer.⁴ More recently, the newer second-generation nonsteroidal androgen receptor antagonist apalutamide has been implicated in several cases of lichenoid drug eruptions.^5,6

We present a case of an apalutamide-induced lichenoid drug eruption that was resistant to dose reduction and required discontinuation of treatment due to the negative impact on the patient’s quality of life. Once the rash resolved, the patient transitioned to enzalutamide without any adverse events (AEs).

A 72-year-old man with a history of metastatic prostate cancer (stage IVB) presented to the dermatology clinic with a 4-month history of a dry itchy rash on the face, chest, back, and legs that had developed 2 to 3 months after oncology started him on apalutamide. The patient initially received apalutamide 240 mg/d, which was reduced by his oncologist 3 months later to 180 mg/d following the appearance of the rash. Then apalutamide was held as he awaited improvement of the rash.

One week after the apalutamide was held, the patient presented to dermatology. He reported that he had tried over-the-counter ammonium lactate 12% lotion twice daily when the rash first developed without improvement. When the apalutamide was held, oncology prescribed mupirocin ointment 2% 3 times daily which yielded minimal relief. On physical examination, widespread lichenified papules and plaques were noted on the face, chest, back, and legs (Figure 1). Dermatology initially prescribed triamcinolone ointment 0.1% twice daily. A 4-mm punch biopsy specimen of the upper back revealed a lichenoid interface dermatitis with numerous eosinophils compatible with a lichenoid hypersensitivity reaction (Figure 2). Considering the clinical and histologic findings, a diagnosis of lichenoid drug eruption secondary to apalutamide treatment was made.

To the Editor:

Lichenoid drug eruptions are lichen planus–like hypersensitivity reactions induced by medications. These reactions are rare but cause irritation to the skin, as extreme pruritus is common. One review of 300 consecutive cases of drug eruptions submitted to dermatopathology revealed that 12% of cases were classified as lichenoid drug reactions.¹ Lichenoid dermatitis is characterized by extremely pruritic, scaly, eczematous or psoriasiform papules, often along the extensor surfaces and trunk.² The pruritic nature of the rash can negatively impact quality of life. Treatment typically involves discontinuation of the offending medication, although complete resolution can take months, even after the drug is stopped. Although there have been some data suggesting that topical and/or oral corticosteroids can help with resolution, the rash can persist even with steroid treatment.²

The histopathologic findings of lichenoid drug eruptions show lichen planus–like changes such as hyperkeratosis, irregular acanthosis, and lichenoid interface dermatitis. Accordingly, idiopathic lichen planus is an important differential diagnosis for lichenoid drug eruptions; however, compared to idiopathic lichen planus, lichenoid drug eruptions are more likely to be associated with eosinophils and parakeratosis.^1,3 In some cases, the histopathologic distinction between the 2 conditions is impossible, and clinical history needs to be considered to make a diagnosis.¹ Drugs known to cause lichenoid drug reactions more commonly include angiotensin-converting enzyme inhibitors, beta blockers, thiazides, gold, penicillamine, and antimalarials.² Lichenoid drug eruptions also have been documented in patients taking the second-generation nonsteroidal androgen receptor antagonist enzalutamide, which is used for the treatment of prostate cancer.⁴ More recently, the newer second-generation nonsteroidal androgen receptor antagonist apalutamide has been implicated in several cases of lichenoid drug eruptions.^5,6

We present a case of an apalutamide-induced lichenoid drug eruption that was resistant to dose reduction and required discontinuation of treatment due to the negative impact on the patient’s quality of life. Once the rash resolved, the patient transitioned to enzalutamide without any adverse events (AEs).

A 72-year-old man with a history of metastatic prostate cancer (stage IVB) presented to the dermatology clinic with a 4-month history of a dry itchy rash on the face, chest, back, and legs that had developed 2 to 3 months after oncology started him on apalutamide. The patient initially received apalutamide 240 mg/d, which was reduced by his oncologist 3 months later to 180 mg/d following the appearance of the rash. Then apalutamide was held as he awaited improvement of the rash.

One week after the apalutamide was held, the patient presented to dermatology. He reported that he had tried over-the-counter ammonium lactate 12% lotion twice daily when the rash first developed without improvement. When the apalutamide was held, oncology prescribed mupirocin ointment 2% 3 times daily which yielded minimal relief. On physical examination, widespread lichenified papules and plaques were noted on the face, chest, back, and legs (Figure 1). Dermatology initially prescribed triamcinolone ointment 0.1% twice daily. A 4-mm punch biopsy specimen of the upper back revealed a lichenoid interface dermatitis with numerous eosinophils compatible with a lichenoid hypersensitivity reaction (Figure 2). Considering the clinical and histologic findings, a diagnosis of lichenoid drug eruption secondary to apalutamide treatment was made.

To the Editor:

Scleroderma is a chronic autoimmune connective tissue disease that results in excessive collagen deposition in the skin and other organs throughout the body. On its own or in the setting of mixed connective tissue disease, scleroderma can result in systemic or localized symptoms that can limit patients’ functional capabilities, cause pain and discomfort, and reduce self-esteem—all negatively impacting patients’ quality of life.^1,2 Neck sclerosis is a common manifestation of scleroderma. There is no curative treatment for scleroderma; thus, therapy is focused on slowing disease progression and improving quality of life. We present a case of neck sclerosis in a 44-year-old woman with scleroderma that was successfully treated with botulinum toxin (BTX) type A injection, resulting in improved skin laxity and appearance with high patient satisfaction. Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region.

A 44-year-old woman presented to the dermatology clinic for treatment of thickened neck skin with stiffness and tightness that had been present for months to years. She had a history of mixed connective tissue disease (MCTD)(positive anti-ribonucleoprotein, anti–Sjögren syndrome–related antigen, and anti-Smith antibodies) with features of scleroderma and polyarthritis. The patient currently was taking sulfasalazine for the polyarthritis; she previously had taken hydroxychloroquine but discontinued treatment due to ineffectiveness. She was not taking any topical or systemic medications for scleroderma. On physical examination, the skin on the anterior neck appeared thickened with shiny patches (Figure 1). Pinching the skin in the affected area demonstrated ­sclerosis with high tension.

Scleroderma is a chronic connective tissue disorder that results in excessive collagen deposition in the skin and other organs throughout the body.⁴ Although the etiology is unknown, scleroderma develops when overactivation of the immune system leads to CD4⁺ T-lymphocyte infiltration in the skin, along with the release of profibrotic interleukins and growth factors, resulting in fibrosis.⁴ Subtypes include localized scleroderma (morphea), limited cutaneous systemic sclerosis (formerly known as CREST [calcinosis, RP, esophageal dysmotility, sclerodactyly, and telangiectasia] syndrome), diffuse cutaneous systemic sclerosis, and systemic sclerosis sine scleroderma.⁵ Scleroderma is associated with positive antinuclear antibodies and HLA II alleles (HLA-DR2 and HLA-DR5).

On its own or in the setting of MCTD, scleroderma can result in systemic or localized symptoms. Overall, the most common symptom is RP.⁵ Localized scleroderma and limited cutaneous systemic sclerosis manifest with symptoms of the skin and underlying tissues. Diffuse cutaneous systemic sclerosis involves cutaneous and visceral symptoms, including lung, esophageal, and vascular involvement.⁶ Similar to MCTD, scleroderma is most prevalent in middle-aged females,⁷ though it occurs at a higher rate and with a more severe disease course in Black patients.⁸

A highly sensitive and specific test for scleroderma that can aid in diagnosis is the neck sign—tightening of the skin of the neck when the head extends.^9,10 In one study, the neck sign was positive in more than 90% of patients with scleroderma and negative for control patients and those with primary RP.⁹ Thus, neck sclerosis is a common manifestation of scleroderma for which patients may seek treatment.

While there is no curative treatment for scleroderma, skin manifestations can be treated with mycophenolate mofetil or methotrexate.⁵ Systemic treatments may be recommended if the patient has additional symptoms, such as azathioprine for myositis/arthritis and cyclophosphamide for interstitial lung disease.⁵ However, it is important to note that these medications are associated with risk for gastrointestinal upset, mouth sores, fatigue, or other complications.

Botulinum toxin is a bacterial protein toxin and neuromodulator that inhibits neurotransmitter release by cleaving SNARE proteins at peripheral nerve terminal junctions.¹¹ It has been used in a variety of dermatologic and nondermatologic conditions, including migraines, hyperhidrosis, contractures, scars, and overactive bladder. It also has been used in aesthetics for facial rejuvenation and minimization of wrinkle appearance. Dermatologists and rheumatologists have successfully used BTX to treat primary and secondary RP—the most common symptom of scleroderma—due to its vasodilatation properties.¹² Although our patient did not have RP, use of BTX to treat other features of scleroderma, including en coup de sabre, thoracic outlet syndrome, dyspareunia, gastroparesis, pterygium inversum unguis, and dysphagia has been documented.^13-18 An in vivo mouse study that examined the possible mechanism for BTX as a treatment in scleroderma found that BTX injections significantly decreased dermal thickness and inflammation in fibrosis (P<.05). An analysis of oxidative stress and mRNA expression showed that BTX may treat fibrosis by suppressing oxidative stress and inflammatory cells, resulting in decreased apoptosis and oxidant-induced intracellular accumulation of reactive oxygen species.¹⁹ Another animal study demonstrated the positive effects of BTX treatment for fibrosis of the bladder in rats.²⁰ In one case report, a female patient with scleroderma and facial fibrosis received perioral BTX injections for cosmetic purposes but also observed improvement in mouth constriction, demonstrating the potential efficacy of BTX for facial fibrosis.²¹

Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region. We recommend assessing the efficacy of the initial BTX treatment after 2 to 3 weeks, with additional injections as needed to achieve the patient’s desired level of comfort and appearance at approximately 3-month intervals (aligning with the expected duration of efficacy of BTX).²² Our patient experienced considerable relief and high satisfaction with BTX treatment. Given the limitations of sclerosis treatments and the unwanted adverse-effect profile of systemic treatments, BTX injections may be a preferrable treatment option for cutaneous manifestations of ­scleroderma among patients. Future studies with larger patient populations and a control group are warranted to further explore the use of BTX for the dermatologic treatment of scleroderma.

To the Editor:

Scleroderma is a chronic autoimmune connective tissue disease that results in excessive collagen deposition in the skin and other organs throughout the body. On its own or in the setting of mixed connective tissue disease, scleroderma can result in systemic or localized symptoms that can limit patients’ functional capabilities, cause pain and discomfort, and reduce self-esteem—all negatively impacting patients’ quality of life.^1,2 Neck sclerosis is a common manifestation of scleroderma. There is no curative treatment for scleroderma; thus, therapy is focused on slowing disease progression and improving quality of life. We present a case of neck sclerosis in a 44-year-old woman with scleroderma that was successfully treated with botulinum toxin (BTX) type A injection, resulting in improved skin laxity and appearance with high patient satisfaction. Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region.

A 44-year-old woman presented to the dermatology clinic for treatment of thickened neck skin with stiffness and tightness that had been present for months to years. She had a history of mixed connective tissue disease (MCTD)(positive anti-ribonucleoprotein, anti–Sjögren syndrome–related antigen, and anti-Smith antibodies) with features of scleroderma and polyarthritis. The patient currently was taking sulfasalazine for the polyarthritis; she previously had taken hydroxychloroquine but discontinued treatment due to ineffectiveness. She was not taking any topical or systemic medications for scleroderma. On physical examination, the skin on the anterior neck appeared thickened with shiny patches (Figure 1). Pinching the skin in the affected area demonstrated ­sclerosis with high tension.

Scleroderma is a chronic connective tissue disorder that results in excessive collagen deposition in the skin and other organs throughout the body.⁴ Although the etiology is unknown, scleroderma develops when overactivation of the immune system leads to CD4⁺ T-lymphocyte infiltration in the skin, along with the release of profibrotic interleukins and growth factors, resulting in fibrosis.⁴ Subtypes include localized scleroderma (morphea), limited cutaneous systemic sclerosis (formerly known as CREST [calcinosis, RP, esophageal dysmotility, sclerodactyly, and telangiectasia] syndrome), diffuse cutaneous systemic sclerosis, and systemic sclerosis sine scleroderma.⁵ Scleroderma is associated with positive antinuclear antibodies and HLA II alleles (HLA-DR2 and HLA-DR5).

On its own or in the setting of MCTD, scleroderma can result in systemic or localized symptoms. Overall, the most common symptom is RP.⁵ Localized scleroderma and limited cutaneous systemic sclerosis manifest with symptoms of the skin and underlying tissues. Diffuse cutaneous systemic sclerosis involves cutaneous and visceral symptoms, including lung, esophageal, and vascular involvement.⁶ Similar to MCTD, scleroderma is most prevalent in middle-aged females,⁷ though it occurs at a higher rate and with a more severe disease course in Black patients.⁸

A highly sensitive and specific test for scleroderma that can aid in diagnosis is the neck sign—tightening of the skin of the neck when the head extends.^9,10 In one study, the neck sign was positive in more than 90% of patients with scleroderma and negative for control patients and those with primary RP.⁹ Thus, neck sclerosis is a common manifestation of scleroderma for which patients may seek treatment.

While there is no curative treatment for scleroderma, skin manifestations can be treated with mycophenolate mofetil or methotrexate.⁵ Systemic treatments may be recommended if the patient has additional symptoms, such as azathioprine for myositis/arthritis and cyclophosphamide for interstitial lung disease.⁵ However, it is important to note that these medications are associated with risk for gastrointestinal upset, mouth sores, fatigue, or other complications.

Botulinum toxin is a bacterial protein toxin and neuromodulator that inhibits neurotransmitter release by cleaving SNARE proteins at peripheral nerve terminal junctions.¹¹ It has been used in a variety of dermatologic and nondermatologic conditions, including migraines, hyperhidrosis, contractures, scars, and overactive bladder. It also has been used in aesthetics for facial rejuvenation and minimization of wrinkle appearance. Dermatologists and rheumatologists have successfully used BTX to treat primary and secondary RP—the most common symptom of scleroderma—due to its vasodilatation properties.¹² Although our patient did not have RP, use of BTX to treat other features of scleroderma, including en coup de sabre, thoracic outlet syndrome, dyspareunia, gastroparesis, pterygium inversum unguis, and dysphagia has been documented.^13-18 An in vivo mouse study that examined the possible mechanism for BTX as a treatment in scleroderma found that BTX injections significantly decreased dermal thickness and inflammation in fibrosis (P<.05). An analysis of oxidative stress and mRNA expression showed that BTX may treat fibrosis by suppressing oxidative stress and inflammatory cells, resulting in decreased apoptosis and oxidant-induced intracellular accumulation of reactive oxygen species.¹⁹ Another animal study demonstrated the positive effects of BTX treatment for fibrosis of the bladder in rats.²⁰ In one case report, a female patient with scleroderma and facial fibrosis received perioral BTX injections for cosmetic purposes but also observed improvement in mouth constriction, demonstrating the potential efficacy of BTX for facial fibrosis.²¹

Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region. We recommend assessing the efficacy of the initial BTX treatment after 2 to 3 weeks, with additional injections as needed to achieve the patient’s desired level of comfort and appearance at approximately 3-month intervals (aligning with the expected duration of efficacy of BTX).²² Our patient experienced considerable relief and high satisfaction with BTX treatment. Given the limitations of sclerosis treatments and the unwanted adverse-effect profile of systemic treatments, BTX injections may be a preferrable treatment option for cutaneous manifestations of ­scleroderma among patients. Future studies with larger patient populations and a control group are warranted to further explore the use of BTX for the dermatologic treatment of scleroderma.

To the Editor:

Scleroderma is a chronic autoimmune connective tissue disease that results in excessive collagen deposition in the skin and other organs throughout the body. On its own or in the setting of mixed connective tissue disease, scleroderma can result in systemic or localized symptoms that can limit patients’ functional capabilities, cause pain and discomfort, and reduce self-esteem—all negatively impacting patients’ quality of life.^1,2 Neck sclerosis is a common manifestation of scleroderma. There is no curative treatment for scleroderma; thus, therapy is focused on slowing disease progression and improving quality of life. We present a case of neck sclerosis in a 44-year-old woman with scleroderma that was successfully treated with botulinum toxin (BTX) type A injection, resulting in improved skin laxity and appearance with high patient satisfaction. Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region.

A 44-year-old woman presented to the dermatology clinic for treatment of thickened neck skin with stiffness and tightness that had been present for months to years. She had a history of mixed connective tissue disease (MCTD)(positive anti-ribonucleoprotein, anti–Sjögren syndrome–related antigen, and anti-Smith antibodies) with features of scleroderma and polyarthritis. The patient currently was taking sulfasalazine for the polyarthritis; she previously had taken hydroxychloroquine but discontinued treatment due to ineffectiveness. She was not taking any topical or systemic medications for scleroderma. On physical examination, the skin on the anterior neck appeared thickened with shiny patches (Figure 1). Pinching the skin in the affected area demonstrated ­sclerosis with high tension.

Scleroderma is a chronic connective tissue disorder that results in excessive collagen deposition in the skin and other organs throughout the body.⁴ Although the etiology is unknown, scleroderma develops when overactivation of the immune system leads to CD4⁺ T-lymphocyte infiltration in the skin, along with the release of profibrotic interleukins and growth factors, resulting in fibrosis.⁴ Subtypes include localized scleroderma (morphea), limited cutaneous systemic sclerosis (formerly known as CREST [calcinosis, RP, esophageal dysmotility, sclerodactyly, and telangiectasia] syndrome), diffuse cutaneous systemic sclerosis, and systemic sclerosis sine scleroderma.⁵ Scleroderma is associated with positive antinuclear antibodies and HLA II alleles (HLA-DR2 and HLA-DR5).

On its own or in the setting of MCTD, scleroderma can result in systemic or localized symptoms. Overall, the most common symptom is RP.⁵ Localized scleroderma and limited cutaneous systemic sclerosis manifest with symptoms of the skin and underlying tissues. Diffuse cutaneous systemic sclerosis involves cutaneous and visceral symptoms, including lung, esophageal, and vascular involvement.⁶ Similar to MCTD, scleroderma is most prevalent in middle-aged females,⁷ though it occurs at a higher rate and with a more severe disease course in Black patients.⁸

A highly sensitive and specific test for scleroderma that can aid in diagnosis is the neck sign—tightening of the skin of the neck when the head extends.^9,10 In one study, the neck sign was positive in more than 90% of patients with scleroderma and negative for control patients and those with primary RP.⁹ Thus, neck sclerosis is a common manifestation of scleroderma for which patients may seek treatment.

While there is no curative treatment for scleroderma, skin manifestations can be treated with mycophenolate mofetil or methotrexate.⁵ Systemic treatments may be recommended if the patient has additional symptoms, such as azathioprine for myositis/arthritis and cyclophosphamide for interstitial lung disease.⁵ However, it is important to note that these medications are associated with risk for gastrointestinal upset, mouth sores, fatigue, or other complications.

Botulinum toxin is a bacterial protein toxin and neuromodulator that inhibits neurotransmitter release by cleaving SNARE proteins at peripheral nerve terminal junctions.¹¹ It has been used in a variety of dermatologic and nondermatologic conditions, including migraines, hyperhidrosis, contractures, scars, and overactive bladder. It also has been used in aesthetics for facial rejuvenation and minimization of wrinkle appearance. Dermatologists and rheumatologists have successfully used BTX to treat primary and secondary RP—the most common symptom of scleroderma—due to its vasodilatation properties.¹² Although our patient did not have RP, use of BTX to treat other features of scleroderma, including en coup de sabre, thoracic outlet syndrome, dyspareunia, gastroparesis, pterygium inversum unguis, and dysphagia has been documented.^13-18 An in vivo mouse study that examined the possible mechanism for BTX as a treatment in scleroderma found that BTX injections significantly decreased dermal thickness and inflammation in fibrosis (P<.05). An analysis of oxidative stress and mRNA expression showed that BTX may treat fibrosis by suppressing oxidative stress and inflammatory cells, resulting in decreased apoptosis and oxidant-induced intracellular accumulation of reactive oxygen species.¹⁹ Another animal study demonstrated the positive effects of BTX treatment for fibrosis of the bladder in rats.²⁰ In one case report, a female patient with scleroderma and facial fibrosis received perioral BTX injections for cosmetic purposes but also observed improvement in mouth constriction, demonstrating the potential efficacy of BTX for facial fibrosis.²¹

Our case demonstrates the potential positive effects of BTX treatment in patients with features of sclerosis or fibrosis, particularly in the neck region. We recommend assessing the efficacy of the initial BTX treatment after 2 to 3 weeks, with additional injections as needed to achieve the patient’s desired level of comfort and appearance at approximately 3-month intervals (aligning with the expected duration of efficacy of BTX).²² Our patient experienced considerable relief and high satisfaction with BTX treatment. Given the limitations of sclerosis treatments and the unwanted adverse-effect profile of systemic treatments, BTX injections may be a preferrable treatment option for cutaneous manifestations of ­scleroderma among patients. Future studies with larger patient populations and a control group are warranted to further explore the use of BTX for the dermatologic treatment of scleroderma.

THE DIAGNOSIS: Acral Hemorrhagic Darier Disease

Darier disease (DD), also known as keratosis follicularis, is a rare autosomal-dominant genodermatosis caused by mutations in the ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2 gene (ATP2A2). This gene encodes the enzyme sarcoplasmic/endoplasmic reticulum calcium ATPase 2, which results in abnormal calcium signaling in keratinocytes and leads to dyskeratosis.¹ Darier disease commonly manifests in the second decade of life with hyperkeratotic papules coalescing into plaques, often accompanied by erosions and fissures that cause discomfort and pruritus. Darier disease also is associated with characteristic nail findings such as the classic candy cane nails and V-shaped nicking.

Acral hemorrhagic lesions are a rare manifestation of DD. Clinically, these lesions can manifest as hemorrhagic macules, papules, and/or vesicles, most commonly occurring following local trauma or retinoid use. Patients with these lesions are believed to have either specific mutations in the ATP2A2 gene that impair sarcoplasmic/endoplasmic reticulum calcium ATPase 2 function in the vascular endothelium or a mutation in the sarcoplasmic/endoplasmic reticulum calcium ATPase protein itself, leading to dysregulation of mitochondrial homeostasis from within the cell, provoking oxidative stress and causing detrimental effects on blood vessels.² Patients with this variant can present with all the features of classic DD concomitantly, with varying symptom severity or distinct clinical features during separate episodic flares, or as the sole manifestation. Other nonclassical lesions of DD include acral keratoderma, giant comedones, keloidlike vegetations, and leucodermic macules (Figure).³

Acral hemorrhagic DD may appear either in isolation or in tandem with more traditional symptoms, necessitating consideration of other possible differential diagnoses such as acrokeratosis verruciformis of Hopf (AKV), porphyria cutanea tarda, bullous lichen planus (BLP), and hemorrhagic lichen sclerosus.

Sometimes regarded as a variant of DD, AKV is an autosomal- dominant genodermatosis characterized by flat or verrucous hyperkeratotic papules on the hands and feet. In AKV, the nails also may be affected, with changes including striations, subungual hyperkeratosis, and V-shaped nicking of the distal nails. Although our patient displayed features of AKV, it has not been associated with acral hemorrhagic macules, making this diagnosis less likely than DD.⁴

Porphyria cutanea tarda, a condition caused by decreased levels of uroporphyrinogen decarboxylase, also can cause skin manifestations such as blistering as well as increased skin fragility, predominantly in sun-exposed areas.⁵ Our patient’s lack of photosensitivity and absence of other common symptoms of this disorder, such as hypertrichosis and hyperpigmentation, made porphyria cutanea tarda less likely.

Bullous lichen planus is a rare subtype of lichen planus characterized by tense bullae arising from preexisting lichen planus lesions or appearing de novo, most commonly manifesting on the oral mucosa or the legs.⁶ The bullae associated with BLP can rupture and form ulcers—a symptom that could potentially be mistaken for hemorrhagic macules like the ones observed in our patient. However, BLP typically is characterized by erythematous, violaceous, polygonal papules commonly appearing on the oral mucosa and the legs with blisters developing near or on pre-existing lichen planus lesions. These are different from the hyperkeratotic papules and leucodermic macules seen in our patient, which aligned more closely with the clinical presentation of DD.

Hemorrhagic lichen sclerosus presents with white atrophic patches and plaques and hemorrhagic bullae, which may resemble the leucodermic macules and hemorrhagic macules of DD. However, hemorrhagic lichen sclerosus most commonly involves the genital area in postmenopausal women. Extragenital manifestations of lichen sclerosus, although less common, can occur and typically manifest on the thighs, buttocks, breasts, back, chest, axillae, shoulders, and wrists.⁷ Notably, these hemorrhagic lesions typically are surrounded by hypopigmented skin and display an atrophic appearance.

Management of DD can be challenging. General measures include sun protection, heat avoidance, and friction reduction. Retinoids are considered the first-line therapy for severe DD, as they help normalize keratinocyte differentiation and reduce keratotic scaling.⁸ Topical corticosteroids can help manage inflammation and reduce the risk for secondary infections. Our patient responded well to this treatment approach, with a notable reduction in the number and severity of the hyperkeratotic plaques and resolution of the acral hemorrhagic lesions.

THE DIAGNOSIS: Acral Hemorrhagic Darier Disease

Darier disease (DD), also known as keratosis follicularis, is a rare autosomal-dominant genodermatosis caused by mutations in the ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2 gene (ATP2A2). This gene encodes the enzyme sarcoplasmic/endoplasmic reticulum calcium ATPase 2, which results in abnormal calcium signaling in keratinocytes and leads to dyskeratosis.¹ Darier disease commonly manifests in the second decade of life with hyperkeratotic papules coalescing into plaques, often accompanied by erosions and fissures that cause discomfort and pruritus. Darier disease also is associated with characteristic nail findings such as the classic candy cane nails and V-shaped nicking.

Acral hemorrhagic lesions are a rare manifestation of DD. Clinically, these lesions can manifest as hemorrhagic macules, papules, and/or vesicles, most commonly occurring following local trauma or retinoid use. Patients with these lesions are believed to have either specific mutations in the ATP2A2 gene that impair sarcoplasmic/endoplasmic reticulum calcium ATPase 2 function in the vascular endothelium or a mutation in the sarcoplasmic/endoplasmic reticulum calcium ATPase protein itself, leading to dysregulation of mitochondrial homeostasis from within the cell, provoking oxidative stress and causing detrimental effects on blood vessels.² Patients with this variant can present with all the features of classic DD concomitantly, with varying symptom severity or distinct clinical features during separate episodic flares, or as the sole manifestation. Other nonclassical lesions of DD include acral keratoderma, giant comedones, keloidlike vegetations, and leucodermic macules (Figure).³

Acral hemorrhagic DD may appear either in isolation or in tandem with more traditional symptoms, necessitating consideration of other possible differential diagnoses such as acrokeratosis verruciformis of Hopf (AKV), porphyria cutanea tarda, bullous lichen planus (BLP), and hemorrhagic lichen sclerosus.

Sometimes regarded as a variant of DD, AKV is an autosomal- dominant genodermatosis characterized by flat or verrucous hyperkeratotic papules on the hands and feet. In AKV, the nails also may be affected, with changes including striations, subungual hyperkeratosis, and V-shaped nicking of the distal nails. Although our patient displayed features of AKV, it has not been associated with acral hemorrhagic macules, making this diagnosis less likely than DD.⁴

Porphyria cutanea tarda, a condition caused by decreased levels of uroporphyrinogen decarboxylase, also can cause skin manifestations such as blistering as well as increased skin fragility, predominantly in sun-exposed areas.⁵ Our patient’s lack of photosensitivity and absence of other common symptoms of this disorder, such as hypertrichosis and hyperpigmentation, made porphyria cutanea tarda less likely.

Bullous lichen planus is a rare subtype of lichen planus characterized by tense bullae arising from preexisting lichen planus lesions or appearing de novo, most commonly manifesting on the oral mucosa or the legs.⁶ The bullae associated with BLP can rupture and form ulcers—a symptom that could potentially be mistaken for hemorrhagic macules like the ones observed in our patient. However, BLP typically is characterized by erythematous, violaceous, polygonal papules commonly appearing on the oral mucosa and the legs with blisters developing near or on pre-existing lichen planus lesions. These are different from the hyperkeratotic papules and leucodermic macules seen in our patient, which aligned more closely with the clinical presentation of DD.

Hemorrhagic lichen sclerosus presents with white atrophic patches and plaques and hemorrhagic bullae, which may resemble the leucodermic macules and hemorrhagic macules of DD. However, hemorrhagic lichen sclerosus most commonly involves the genital area in postmenopausal women. Extragenital manifestations of lichen sclerosus, although less common, can occur and typically manifest on the thighs, buttocks, breasts, back, chest, axillae, shoulders, and wrists.⁷ Notably, these hemorrhagic lesions typically are surrounded by hypopigmented skin and display an atrophic appearance.

Management of DD can be challenging. General measures include sun protection, heat avoidance, and friction reduction. Retinoids are considered the first-line therapy for severe DD, as they help normalize keratinocyte differentiation and reduce keratotic scaling.⁸ Topical corticosteroids can help manage inflammation and reduce the risk for secondary infections. Our patient responded well to this treatment approach, with a notable reduction in the number and severity of the hyperkeratotic plaques and resolution of the acral hemorrhagic lesions.

THE DIAGNOSIS: Acral Hemorrhagic Darier Disease

Darier disease (DD), also known as keratosis follicularis, is a rare autosomal-dominant genodermatosis caused by mutations in the ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2 gene (ATP2A2). This gene encodes the enzyme sarcoplasmic/endoplasmic reticulum calcium ATPase 2, which results in abnormal calcium signaling in keratinocytes and leads to dyskeratosis.¹ Darier disease commonly manifests in the second decade of life with hyperkeratotic papules coalescing into plaques, often accompanied by erosions and fissures that cause discomfort and pruritus. Darier disease also is associated with characteristic nail findings such as the classic candy cane nails and V-shaped nicking.

Acral hemorrhagic lesions are a rare manifestation of DD. Clinically, these lesions can manifest as hemorrhagic macules, papules, and/or vesicles, most commonly occurring following local trauma or retinoid use. Patients with these lesions are believed to have either specific mutations in the ATP2A2 gene that impair sarcoplasmic/endoplasmic reticulum calcium ATPase 2 function in the vascular endothelium or a mutation in the sarcoplasmic/endoplasmic reticulum calcium ATPase protein itself, leading to dysregulation of mitochondrial homeostasis from within the cell, provoking oxidative stress and causing detrimental effects on blood vessels.² Patients with this variant can present with all the features of classic DD concomitantly, with varying symptom severity or distinct clinical features during separate episodic flares, or as the sole manifestation. Other nonclassical lesions of DD include acral keratoderma, giant comedones, keloidlike vegetations, and leucodermic macules (Figure).³

Acral hemorrhagic DD may appear either in isolation or in tandem with more traditional symptoms, necessitating consideration of other possible differential diagnoses such as acrokeratosis verruciformis of Hopf (AKV), porphyria cutanea tarda, bullous lichen planus (BLP), and hemorrhagic lichen sclerosus.

Sometimes regarded as a variant of DD, AKV is an autosomal- dominant genodermatosis characterized by flat or verrucous hyperkeratotic papules on the hands and feet. In AKV, the nails also may be affected, with changes including striations, subungual hyperkeratosis, and V-shaped nicking of the distal nails. Although our patient displayed features of AKV, it has not been associated with acral hemorrhagic macules, making this diagnosis less likely than DD.⁴

Porphyria cutanea tarda, a condition caused by decreased levels of uroporphyrinogen decarboxylase, also can cause skin manifestations such as blistering as well as increased skin fragility, predominantly in sun-exposed areas.⁵ Our patient’s lack of photosensitivity and absence of other common symptoms of this disorder, such as hypertrichosis and hyperpigmentation, made porphyria cutanea tarda less likely.

Bullous lichen planus is a rare subtype of lichen planus characterized by tense bullae arising from preexisting lichen planus lesions or appearing de novo, most commonly manifesting on the oral mucosa or the legs.⁶ The bullae associated with BLP can rupture and form ulcers—a symptom that could potentially be mistaken for hemorrhagic macules like the ones observed in our patient. However, BLP typically is characterized by erythematous, violaceous, polygonal papules commonly appearing on the oral mucosa and the legs with blisters developing near or on pre-existing lichen planus lesions. These are different from the hyperkeratotic papules and leucodermic macules seen in our patient, which aligned more closely with the clinical presentation of DD.

Hemorrhagic lichen sclerosus presents with white atrophic patches and plaques and hemorrhagic bullae, which may resemble the leucodermic macules and hemorrhagic macules of DD. However, hemorrhagic lichen sclerosus most commonly involves the genital area in postmenopausal women. Extragenital manifestations of lichen sclerosus, although less common, can occur and typically manifest on the thighs, buttocks, breasts, back, chest, axillae, shoulders, and wrists.⁷ Notably, these hemorrhagic lesions typically are surrounded by hypopigmented skin and display an atrophic appearance.

Management of DD can be challenging. General measures include sun protection, heat avoidance, and friction reduction. Retinoids are considered the first-line therapy for severe DD, as they help normalize keratinocyte differentiation and reduce keratotic scaling.⁸ Topical corticosteroids can help manage inflammation and reduce the risk for secondary infections. Our patient responded well to this treatment approach, with a notable reduction in the number and severity of the hyperkeratotic plaques and resolution of the acral hemorrhagic lesions.

The sun often is rising in the rearview mirror as I travel with the University of New Mexico dermatology team from Albuquerque to our satellite clinic in Gallup, New Mexico. This twice-monthly trip—with a group usually comprising an attending physician, residents, and medical students—provides an invaluable opportunity for me to take part in delivering care to a majority Native American population and connects our institution and its trainees to the state’s rural and indigenous cultures and communities.

Community outreach is an important initiative for many dermatology residency training programs. Engaging with the community outside the clinic setting allows residents to hone their clinical skills, interact with and meet new people, and help to improve access to health care, especially for members of underserved populations.

Limited access to health care remains a pressing issue in the United States, especially for underserved and rural communities. There currently is no standardized way to measure access to care, but multiple contributing factors have been identified, including but not limited to patient wait times and throughput, provider turnover, ratio of dermatologists to patient population, insurance type, and patient outcomes.¹ Fortunately, there are many ways for dermatology residents to get involved and improve access to dermatologic services in their communities, including skin cancer screenings, free clinics, and teledermatology.

Skin Cancer Screenings

More than 40% of community outreach initiatives offered by dermatology residency programs are related to skin cancer screening and prevention.² The American Academy of Dermatology’s free skin cancer check program (https://www.aad.org/member/career/volunteer/spot) offers a way to participate in or even host a skin cancer screening in your community. Since 1985, this program has identified nearly 300,000 suspicious lesions and more than 30,000 suspected melanomas. Resources for setting up a skin cancer screening in your community are available on the program’s website. Residents may take this opportunity to teach medical students how to perform full-body skin examinations and/or practice making independent decisions as the supervisor for medical trainees. Skin cancer screening events not only expand access to care in underserved communities but also help residents feel more connected to the local community, especially if they have moved to a new location for their residency training.

Free Clinics

Engaging in educational opportunities offered through residency programs is another way to participate in community outreach. In particular, many programs are affiliated with a School of Medicine within their institution that allows residents to spearhead volunteer opportunities such as working at a free clinic. In fact, more than 30% of initiatives offered at dermatology residency programs are free general dermatology clinics.² Residents are in the unique position of being both learners themselves as well as educators to trainees.³ As part of our role, we can provide crucial specialty care to the community by working in concert with medical students and while also familiarizing ourselves with treating populations that we may not reach in our daily clinical work. For example, by participating in free clinics, we can provide care to vulnerable populations who typically may have financial or time barriers that prevent them from seeking care at the institution-associated clinic, including individuals experiencing homelessness, patients who are uninsured, and individuals who cannot take time off work to pursue medical care. Our presence in the community helps to reduce barriers to specialty care, particularly in the field of dermatology where the access shortage in the context of rising skin cancer rates prompts public health concerns.⁴

Teledermatology

Teledermatology became a way to extend our reach in the community more than ever before during the COVID-19 pandemic. Advances in audio, visual, and data telecommunication have been particularly helpful in dermatology, a specialty that relies heavily on visual cues for diagnosis. Synchronous, asynchronous, and hybrid teledermatology services implemented during the pandemic have gained favor among patients and dermatologists and are still applied in current practice.^5,6

For example, in the state of New Mexico (where there is a severe shortage of board-certified dermatologists to care for the state’s population), teledermatology has allowed rural providers of all specialties to consult University of New Mexico dermatologists by sending clinical photographs along with patient information and history via secure messaging. Instead of having the patient travel hundreds of miles to see the nearest dermatologist for their skin condition or endure long wait times to get in to see a specialist, primary providers now can initiate treatment or work-up for their patient’s skin issue in a timely manner with the use of teledermatology to consult specialists.

Teledermatology has demonstrated cost-effectiveness, accuracy, and efficiency in conveniently expanding access to care. It offers patients and dermatologists flexibility in receiving and delivering health care, respectively.⁷ As residents, learning how to navigate this technologic frontier in health care delivery is imperative, as it will remain a prevalent tool in the future care of our communities, particularly in underserved areas.

Final Thoughts

Through community outreach initiatives, dermatology residents have an opportunity not only to enrich our education but also to connect with and become closer to our patients. Skin cancer screenings, free clinics, and teledermatology have provided ways to reach more communities and remain important aspects of dermatology residency.

The sun often is rising in the rearview mirror as I travel with the University of New Mexico dermatology team from Albuquerque to our satellite clinic in Gallup, New Mexico. This twice-monthly trip—with a group usually comprising an attending physician, residents, and medical students—provides an invaluable opportunity for me to take part in delivering care to a majority Native American population and connects our institution and its trainees to the state’s rural and indigenous cultures and communities.

Community outreach is an important initiative for many dermatology residency training programs. Engaging with the community outside the clinic setting allows residents to hone their clinical skills, interact with and meet new people, and help to improve access to health care, especially for members of underserved populations.

Limited access to health care remains a pressing issue in the United States, especially for underserved and rural communities. There currently is no standardized way to measure access to care, but multiple contributing factors have been identified, including but not limited to patient wait times and throughput, provider turnover, ratio of dermatologists to patient population, insurance type, and patient outcomes.¹ Fortunately, there are many ways for dermatology residents to get involved and improve access to dermatologic services in their communities, including skin cancer screenings, free clinics, and teledermatology.

Skin Cancer Screenings

More than 40% of community outreach initiatives offered by dermatology residency programs are related to skin cancer screening and prevention.² The American Academy of Dermatology’s free skin cancer check program (https://www.aad.org/member/career/volunteer/spot) offers a way to participate in or even host a skin cancer screening in your community. Since 1985, this program has identified nearly 300,000 suspicious lesions and more than 30,000 suspected melanomas. Resources for setting up a skin cancer screening in your community are available on the program’s website. Residents may take this opportunity to teach medical students how to perform full-body skin examinations and/or practice making independent decisions as the supervisor for medical trainees. Skin cancer screening events not only expand access to care in underserved communities but also help residents feel more connected to the local community, especially if they have moved to a new location for their residency training.

Free Clinics

Engaging in educational opportunities offered through residency programs is another way to participate in community outreach. In particular, many programs are affiliated with a School of Medicine within their institution that allows residents to spearhead volunteer opportunities such as working at a free clinic. In fact, more than 30% of initiatives offered at dermatology residency programs are free general dermatology clinics.² Residents are in the unique position of being both learners themselves as well as educators to trainees.³ As part of our role, we can provide crucial specialty care to the community by working in concert with medical students and while also familiarizing ourselves with treating populations that we may not reach in our daily clinical work. For example, by participating in free clinics, we can provide care to vulnerable populations who typically may have financial or time barriers that prevent them from seeking care at the institution-associated clinic, including individuals experiencing homelessness, patients who are uninsured, and individuals who cannot take time off work to pursue medical care. Our presence in the community helps to reduce barriers to specialty care, particularly in the field of dermatology where the access shortage in the context of rising skin cancer rates prompts public health concerns.⁴

Teledermatology

Teledermatology became a way to extend our reach in the community more than ever before during the COVID-19 pandemic. Advances in audio, visual, and data telecommunication have been particularly helpful in dermatology, a specialty that relies heavily on visual cues for diagnosis. Synchronous, asynchronous, and hybrid teledermatology services implemented during the pandemic have gained favor among patients and dermatologists and are still applied in current practice.^5,6

For example, in the state of New Mexico (where there is a severe shortage of board-certified dermatologists to care for the state’s population), teledermatology has allowed rural providers of all specialties to consult University of New Mexico dermatologists by sending clinical photographs along with patient information and history via secure messaging. Instead of having the patient travel hundreds of miles to see the nearest dermatologist for their skin condition or endure long wait times to get in to see a specialist, primary providers now can initiate treatment or work-up for their patient’s skin issue in a timely manner with the use of teledermatology to consult specialists.

Teledermatology has demonstrated cost-effectiveness, accuracy, and efficiency in conveniently expanding access to care. It offers patients and dermatologists flexibility in receiving and delivering health care, respectively.⁷ As residents, learning how to navigate this technologic frontier in health care delivery is imperative, as it will remain a prevalent tool in the future care of our communities, particularly in underserved areas.

Final Thoughts

Through community outreach initiatives, dermatology residents have an opportunity not only to enrich our education but also to connect with and become closer to our patients. Skin cancer screenings, free clinics, and teledermatology have provided ways to reach more communities and remain important aspects of dermatology residency.

The sun often is rising in the rearview mirror as I travel with the University of New Mexico dermatology team from Albuquerque to our satellite clinic in Gallup, New Mexico. This twice-monthly trip—with a group usually comprising an attending physician, residents, and medical students—provides an invaluable opportunity for me to take part in delivering care to a majority Native American population and connects our institution and its trainees to the state’s rural and indigenous cultures and communities.

Community outreach is an important initiative for many dermatology residency training programs. Engaging with the community outside the clinic setting allows residents to hone their clinical skills, interact with and meet new people, and help to improve access to health care, especially for members of underserved populations.

Limited access to health care remains a pressing issue in the United States, especially for underserved and rural communities. There currently is no standardized way to measure access to care, but multiple contributing factors have been identified, including but not limited to patient wait times and throughput, provider turnover, ratio of dermatologists to patient population, insurance type, and patient outcomes.¹ Fortunately, there are many ways for dermatology residents to get involved and improve access to dermatologic services in their communities, including skin cancer screenings, free clinics, and teledermatology.

Skin Cancer Screenings

More than 40% of community outreach initiatives offered by dermatology residency programs are related to skin cancer screening and prevention.² The American Academy of Dermatology’s free skin cancer check program (https://www.aad.org/member/career/volunteer/spot) offers a way to participate in or even host a skin cancer screening in your community. Since 1985, this program has identified nearly 300,000 suspicious lesions and more than 30,000 suspected melanomas. Resources for setting up a skin cancer screening in your community are available on the program’s website. Residents may take this opportunity to teach medical students how to perform full-body skin examinations and/or practice making independent decisions as the supervisor for medical trainees. Skin cancer screening events not only expand access to care in underserved communities but also help residents feel more connected to the local community, especially if they have moved to a new location for their residency training.

Free Clinics

Engaging in educational opportunities offered through residency programs is another way to participate in community outreach. In particular, many programs are affiliated with a School of Medicine within their institution that allows residents to spearhead volunteer opportunities such as working at a free clinic. In fact, more than 30% of initiatives offered at dermatology residency programs are free general dermatology clinics.² Residents are in the unique position of being both learners themselves as well as educators to trainees.³ As part of our role, we can provide crucial specialty care to the community by working in concert with medical students and while also familiarizing ourselves with treating populations that we may not reach in our daily clinical work. For example, by participating in free clinics, we can provide care to vulnerable populations who typically may have financial or time barriers that prevent them from seeking care at the institution-associated clinic, including individuals experiencing homelessness, patients who are uninsured, and individuals who cannot take time off work to pursue medical care. Our presence in the community helps to reduce barriers to specialty care, particularly in the field of dermatology where the access shortage in the context of rising skin cancer rates prompts public health concerns.⁴

Teledermatology

Teledermatology became a way to extend our reach in the community more than ever before during the COVID-19 pandemic. Advances in audio, visual, and data telecommunication have been particularly helpful in dermatology, a specialty that relies heavily on visual cues for diagnosis. Synchronous, asynchronous, and hybrid teledermatology services implemented during the pandemic have gained favor among patients and dermatologists and are still applied in current practice.^5,6

For example, in the state of New Mexico (where there is a severe shortage of board-certified dermatologists to care for the state’s population), teledermatology has allowed rural providers of all specialties to consult University of New Mexico dermatologists by sending clinical photographs along with patient information and history via secure messaging. Instead of having the patient travel hundreds of miles to see the nearest dermatologist for their skin condition or endure long wait times to get in to see a specialist, primary providers now can initiate treatment or work-up for their patient’s skin issue in a timely manner with the use of teledermatology to consult specialists.

Teledermatology has demonstrated cost-effectiveness, accuracy, and efficiency in conveniently expanding access to care. It offers patients and dermatologists flexibility in receiving and delivering health care, respectively.⁷ As residents, learning how to navigate this technologic frontier in health care delivery is imperative, as it will remain a prevalent tool in the future care of our communities, particularly in underserved areas.

Final Thoughts

Through community outreach initiatives, dermatology residents have an opportunity not only to enrich our education but also to connect with and become closer to our patients. Skin cancer screenings, free clinics, and teledermatology have provided ways to reach more communities and remain important aspects of dermatology residency.

THE DIAGNOSIS: Chemotherapy-Induced Flagellate Dermatitis

Based on the clinical presentation and temporal relation with chemotherapy, a diagnosis of bleomycininduced flagellate dermatitis (FD) was made, as bleomycin is the only chemotherapeutic agent from this regimen that has been linked with FD.^1,2 Laboratory findings revealed eosinophilia, further supporting a druginduced dermatitis. The patient was treated with oral steroids and diphenhydramine to alleviate itching and discomfort. The chemotherapy was temporarily discontinued until symptomatic improvement was observed within 2 to 3 days.

Flagellate dermatitis is characterized by unique erythematous, linear, intermingled streaks of adjoining firm papules—often preceded by a prodrome of global pruritus—that eventually become hyperpigmented as the erythema subsides. The clinical manifestation of FD can be idiopathic; true/mechanical (dermatitis artefacta, abuse, sadomasochism); chemotherapy induced (peplomycin, trastuzumab, cisplatin, docetaxel, bendamustine); toxin induced (shiitake mushroom, cnidarian stings, Paederus insects); related to rheumatologic diseases (dermatomyositis, adult-onset Still disease), dermatographism, phytophotodermatitis, or poison ivy dermatitis; or induced by chikungunya fever.¹

The term flagellate originates from the Latin word flagellum, which pertains to the distinctive whiplike pattern. It was first described by Moulin et al³ in 1970 in reference to bleomycin-induced linear hyperpigmentation. Bleomycin, a glycopeptide antibiotic derived from Streptomyces verticillus, is used to treat Hodgkin lymphoma, squamous cell carcinoma, and germ cell tumors. The worldwide incidence of bleomycin-induced FD is 8% to 22% and commonly is associated with a cumulative dose greater than 100 U.² Clinical presentation is variable in terms of onset, distribution, and morphology of the eruption and could be independent of dose, route of administration, or type of malignancy being treated. The flagellate rash commonly involves the trunk, arms, and legs; can develop within hours to 6 months of starting bleomycin therapy; often is preceded by generalized itching; and eventually heals with hyperpigmentation.

Possible mechanisms of bleomycin-induced FD include localized melanogenesis, inflammatory pigmentary incontinence, alterations to normal pigmentation patterns, cytotoxic effects of the drug itself, minor trauma/ scratching leading to increased blood flow and causing local accumulation of bleomycin, heat recall, and reduced epidermal turnover leading to extended interaction between keratinocytes and melanocytes.² Heat exposure can act as a trigger for bleomycin-induced skin rash recall even months after the treatment is stopped.

Apart from discontinuing the drug, there is no specific treatment available for bleomycin-induced FD. The primary objective of treatment is to alleviate pruritus, which often involves the use of topical or systemic corticosteroids and oral antihistamines. The duration of treatment depends on the patient’s clinical response. Once treatment is discontinued, FD typically resolves within 6 to 8 months. However, there can be a permanent postinflammatory hyperpigmentation in the affected area.⁴ Although there is a concern for increased mortality after postponement of chemotherapy,⁵ the decision to proceed with or discontinue the chemotherapy regimen necessitates a comprehensive interdisciplinary discussion and a meticulous assessment of the risks and benefits that is customized to each individual patient. Flagellate dermatitis can reoccur with bleomycin re-exposure; a combined approach of proactive topical and systemic steroid treatment seems to diminish the likelihood of FD recurrence.⁵

Our case underscores the importance of recognizing, detecting, and managing FD promptly in individuals undergoing bleomycin-based chemotherapy. Medical professionals should familiarize themselves with this distinct adverse effect linked to bleomycin, enabling prompt discontinuation if necessary, and educate patients about the condition’s typically temporary nature, thereby alleviating their concerns.

THE DIAGNOSIS: Chemotherapy-Induced Flagellate Dermatitis

Based on the clinical presentation and temporal relation with chemotherapy, a diagnosis of bleomycininduced flagellate dermatitis (FD) was made, as bleomycin is the only chemotherapeutic agent from this regimen that has been linked with FD.^1,2 Laboratory findings revealed eosinophilia, further supporting a druginduced dermatitis. The patient was treated with oral steroids and diphenhydramine to alleviate itching and discomfort. The chemotherapy was temporarily discontinued until symptomatic improvement was observed within 2 to 3 days.

Flagellate dermatitis is characterized by unique erythematous, linear, intermingled streaks of adjoining firm papules—often preceded by a prodrome of global pruritus—that eventually become hyperpigmented as the erythema subsides. The clinical manifestation of FD can be idiopathic; true/mechanical (dermatitis artefacta, abuse, sadomasochism); chemotherapy induced (peplomycin, trastuzumab, cisplatin, docetaxel, bendamustine); toxin induced (shiitake mushroom, cnidarian stings, Paederus insects); related to rheumatologic diseases (dermatomyositis, adult-onset Still disease), dermatographism, phytophotodermatitis, or poison ivy dermatitis; or induced by chikungunya fever.¹

The term flagellate originates from the Latin word flagellum, which pertains to the distinctive whiplike pattern. It was first described by Moulin et al³ in 1970 in reference to bleomycin-induced linear hyperpigmentation. Bleomycin, a glycopeptide antibiotic derived from Streptomyces verticillus, is used to treat Hodgkin lymphoma, squamous cell carcinoma, and germ cell tumors. The worldwide incidence of bleomycin-induced FD is 8% to 22% and commonly is associated with a cumulative dose greater than 100 U.² Clinical presentation is variable in terms of onset, distribution, and morphology of the eruption and could be independent of dose, route of administration, or type of malignancy being treated. The flagellate rash commonly involves the trunk, arms, and legs; can develop within hours to 6 months of starting bleomycin therapy; often is preceded by generalized itching; and eventually heals with hyperpigmentation.

Possible mechanisms of bleomycin-induced FD include localized melanogenesis, inflammatory pigmentary incontinence, alterations to normal pigmentation patterns, cytotoxic effects of the drug itself, minor trauma/ scratching leading to increased blood flow and causing local accumulation of bleomycin, heat recall, and reduced epidermal turnover leading to extended interaction between keratinocytes and melanocytes.² Heat exposure can act as a trigger for bleomycin-induced skin rash recall even months after the treatment is stopped.

Apart from discontinuing the drug, there is no specific treatment available for bleomycin-induced FD. The primary objective of treatment is to alleviate pruritus, which often involves the use of topical or systemic corticosteroids and oral antihistamines. The duration of treatment depends on the patient’s clinical response. Once treatment is discontinued, FD typically resolves within 6 to 8 months. However, there can be a permanent postinflammatory hyperpigmentation in the affected area.⁴ Although there is a concern for increased mortality after postponement of chemotherapy,⁵ the decision to proceed with or discontinue the chemotherapy regimen necessitates a comprehensive interdisciplinary discussion and a meticulous assessment of the risks and benefits that is customized to each individual patient. Flagellate dermatitis can reoccur with bleomycin re-exposure; a combined approach of proactive topical and systemic steroid treatment seems to diminish the likelihood of FD recurrence.⁵

Our case underscores the importance of recognizing, detecting, and managing FD promptly in individuals undergoing bleomycin-based chemotherapy. Medical professionals should familiarize themselves with this distinct adverse effect linked to bleomycin, enabling prompt discontinuation if necessary, and educate patients about the condition’s typically temporary nature, thereby alleviating their concerns.

THE DIAGNOSIS: Chemotherapy-Induced Flagellate Dermatitis

Based on the clinical presentation and temporal relation with chemotherapy, a diagnosis of bleomycininduced flagellate dermatitis (FD) was made, as bleomycin is the only chemotherapeutic agent from this regimen that has been linked with FD.^1,2 Laboratory findings revealed eosinophilia, further supporting a druginduced dermatitis. The patient was treated with oral steroids and diphenhydramine to alleviate itching and discomfort. The chemotherapy was temporarily discontinued until symptomatic improvement was observed within 2 to 3 days.

Flagellate dermatitis is characterized by unique erythematous, linear, intermingled streaks of adjoining firm papules—often preceded by a prodrome of global pruritus—that eventually become hyperpigmented as the erythema subsides. The clinical manifestation of FD can be idiopathic; true/mechanical (dermatitis artefacta, abuse, sadomasochism); chemotherapy induced (peplomycin, trastuzumab, cisplatin, docetaxel, bendamustine); toxin induced (shiitake mushroom, cnidarian stings, Paederus insects); related to rheumatologic diseases (dermatomyositis, adult-onset Still disease), dermatographism, phytophotodermatitis, or poison ivy dermatitis; or induced by chikungunya fever.¹

The term flagellate originates from the Latin word flagellum, which pertains to the distinctive whiplike pattern. It was first described by Moulin et al³ in 1970 in reference to bleomycin-induced linear hyperpigmentation. Bleomycin, a glycopeptide antibiotic derived from Streptomyces verticillus, is used to treat Hodgkin lymphoma, squamous cell carcinoma, and germ cell tumors. The worldwide incidence of bleomycin-induced FD is 8% to 22% and commonly is associated with a cumulative dose greater than 100 U.² Clinical presentation is variable in terms of onset, distribution, and morphology of the eruption and could be independent of dose, route of administration, or type of malignancy being treated. The flagellate rash commonly involves the trunk, arms, and legs; can develop within hours to 6 months of starting bleomycin therapy; often is preceded by generalized itching; and eventually heals with hyperpigmentation.

Possible mechanisms of bleomycin-induced FD include localized melanogenesis, inflammatory pigmentary incontinence, alterations to normal pigmentation patterns, cytotoxic effects of the drug itself, minor trauma/ scratching leading to increased blood flow and causing local accumulation of bleomycin, heat recall, and reduced epidermal turnover leading to extended interaction between keratinocytes and melanocytes.² Heat exposure can act as a trigger for bleomycin-induced skin rash recall even months after the treatment is stopped.

Apart from discontinuing the drug, there is no specific treatment available for bleomycin-induced FD. The primary objective of treatment is to alleviate pruritus, which often involves the use of topical or systemic corticosteroids and oral antihistamines. The duration of treatment depends on the patient’s clinical response. Once treatment is discontinued, FD typically resolves within 6 to 8 months. However, there can be a permanent postinflammatory hyperpigmentation in the affected area.⁴ Although there is a concern for increased mortality after postponement of chemotherapy,⁵ the decision to proceed with or discontinue the chemotherapy regimen necessitates a comprehensive interdisciplinary discussion and a meticulous assessment of the risks and benefits that is customized to each individual patient. Flagellate dermatitis can reoccur with bleomycin re-exposure; a combined approach of proactive topical and systemic steroid treatment seems to diminish the likelihood of FD recurrence.⁵

Our case underscores the importance of recognizing, detecting, and managing FD promptly in individuals undergoing bleomycin-based chemotherapy. Medical professionals should familiarize themselves with this distinct adverse effect linked to bleomycin, enabling prompt discontinuation if necessary, and educate patients about the condition’s typically temporary nature, thereby alleviating their concerns.

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

What is the world’s most dangerous tree? According to Guinness World Records¹ (and one unlucky contestant on the wilderness survival reality show Naked and Afraid,² who got its sap in his eyes and needed to be evacuated for treatment), the manchineel tree (Hippomane mancinella) has earned this designation.^1-3 Manchineel trees are part of the strand vegetation of islands in the West Indies and along the Caribbean coasts of South and Central America, where their copious root systems help reduce coastal erosion. In the United States, this poisonous tree grows along the southern edge of Florida’s Everglades National Park; the Florida Keys; and the US Virgin Islands, especially Virgin Islands National Park. Although the manchineel tree appears on several endangered species lists,^4-6 there are places within its distribution where it is locally abundant and thus poses a risk to residents and visitors.

The first European description of manchineel toxicity was by Peter Martyr d’Anghiera, a court historian and geographer of Christopher Columbus’s patroness, Isabella I, Queen of Castile and Léon. In the early 1500s, Peter Martyr wrote that on Columbus’s second New World voyage in 1493, the crew encountered a mysterious tree that burned the skin and eyes of anyone who had contact with it.⁷ Columbus called the tree’s fruit manzanilla de la muerte (“little apple of death”) after several sailors became severely ill from eating the fruit.^8,9 Manchineel lore is rife with tales of agonizing death after eating the applelike fruit, and several contemporaneous accounts describe indigenous Caribbean islanders using manchineel’s toxic sap as an arrow poison.¹⁰

Eating manchineel fruit is known to cause abdominal pain, burning sensations in the oropharynx, and esophageal spasms.¹¹ Several case reports mention that consuming the fruit can create an exaggerated parasympathomimetic syndrome due to suspected anticholinesteraselike compounds.^3,11,12 Ophthalmologic injuries include severe conjunctivitis—sometimes extensive enough to cause superficial punctate epithelial keratitis.⁵ Dermatologic injuries have been described, but reports on its histopathologic features are limited. We present a case of manchineel dermatitis in a patient who subsequently underwent a skin biopsy.

Case Report

A 64-year-old physician (S.A.N.) came across a stand of manchineel trees while camping in the Virgin Islands National Park on St. John in the US Virgin Islands (Figure 1). The patient—who was knowledgeable about tropical ecology and was familiar with the tree—was curious about its purported cutaneous toxicity and applied the viscous white sap of a broken branchlet (Figure 2) to a patch of skin measuring 4 cm in diameter on the medial left calf. He took serial photographs of the site on days 2, 4 (Figure 3), 6, and 10 (Figure 4), showing the onset of erythema and the subsequent development of follicular pustules. On day 6, a 4-mm punch biopsy specimen was taken of the most prominent pustule. Histopathology showed a subcorneal acantholytic blister and epidermal spongiosis overlying a mixed perivascular infiltrate and follicular necrosis, which was consistent with irritant contact dermatitis (Figure 5). On day 8, the region became indurated and tender to pressure; however, there was no warmth, edema, purulent drainage, lymphangitic streaks, or other signs of infection. The region was never itchy; it was uncomfortable only with firm direct pressure. The patient applied hot compresses to the site for 10 minutes 1 to 2 times daily for roughly 2 weeks, and the affected area healed fully (without any additional intervention) in approximately 6 weeks.

Comment

Manchineel is a member of the Euphorbiaceae (also known as the euphorb or spurge) family, a mainly tropical or subtropical plant family that includes many useful as well as many toxic species. Examples of useful plants include cassava (Manihot esculenta) and the rubber tree (Hevea brasiliensis). Many euphorbs have well-described toxicities, and many (eg, castor bean, Ricinus communis) are useful in some circumstances and toxic in others.^6,12-14 Many euphorbs are known to cause skin reactions, usually due to toxins in the milky sap that directly irritate the skin or to latex compounds that can induce IgE-mediated contact dermatitis.^9,14

Manchineel contains a complex mix of toxins, though no specific one has been identified as the main cause of the associated irritant contact dermatitis. Manchineel sap (and sap of many other euphorbs) contains phorbol esters that may cause direct pH-induced cytotoxicity leading to keratinocyte necrosis. Diterpenes may augment this cytotoxic effect via induction of proinflammatory cytokines.¹² Pitts et al⁵ pointed to a mixture of oxygenated diterpene esters as the primary cause of toxicity and suggested that their water solubility explained occurrences of keratoconjunctivitis after contact with rainwater or dew from the manchineel tree.

All parts of the manchineel tree—fruit, leaves, wood, and sap—are poisonous. In a retrospective series of 97 cases of manchineel fruit ingestion, the most common symptoms were oropharyngeal pain (68% [66/97]), abdominal pain (42% [41/97]), and diarrhea (37% [36/97]). The same series identified 1 (1%) case of bradycardia and hypotension.³ Contact with the wood, exposure to sawdust, and inhalation of smoke from burning the wood can irritate the skin, conjunctivae, or nasopharynx. Rainwater or dew dripping from the leaves onto the skin can cause dermatitis and ophthalmitis, even without direct contact with the tree.^4,5

Management—There is no specific treatment for manchineel dermatitis. Because it is an irritant reaction and not a type IV hypersensitivity reaction, topical corticosteroids have minimal benefit. A regimen consisting of a thorough cleansing, wet compresses, and observation, as most symptoms resolve spontaneously within a few days, has been recommended.⁴ Our patient used hot compresses, which he believes helped heal the site, although his symptoms lasted for several weeks.

Given that there is no specific treatment for manchineel dermatitis, the wisest approach is strict avoidance. On many Caribbean islands, visitors are warned about the manchineel tree, advised to avoid direct contact, and reminded to avoid standing beneath it during a rainstorm (Figure 6).

Conclusion

This article begins with a question: “What is the world’s most dangerous tree?” Many sources from the indexed medical literature as well as the popular press and social media state that it is the manchineel. Although all parts of the manchineel tree are highly toxic, human exposures are uncommon, and deaths are more apocryphal than actual.

What is the world’s most dangerous tree? According to Guinness World Records¹ (and one unlucky contestant on the wilderness survival reality show Naked and Afraid,² who got its sap in his eyes and needed to be evacuated for treatment), the manchineel tree (Hippomane mancinella) has earned this designation.^1-3 Manchineel trees are part of the strand vegetation of islands in the West Indies and along the Caribbean coasts of South and Central America, where their copious root systems help reduce coastal erosion. In the United States, this poisonous tree grows along the southern edge of Florida’s Everglades National Park; the Florida Keys; and the US Virgin Islands, especially Virgin Islands National Park. Although the manchineel tree appears on several endangered species lists,^4-6 there are places within its distribution where it is locally abundant and thus poses a risk to residents and visitors.

The first European description of manchineel toxicity was by Peter Martyr d’Anghiera, a court historian and geographer of Christopher Columbus’s patroness, Isabella I, Queen of Castile and Léon. In the early 1500s, Peter Martyr wrote that on Columbus’s second New World voyage in 1493, the crew encountered a mysterious tree that burned the skin and eyes of anyone who had contact with it.⁷ Columbus called the tree’s fruit manzanilla de la muerte (“little apple of death”) after several sailors became severely ill from eating the fruit.^8,9 Manchineel lore is rife with tales of agonizing death after eating the applelike fruit, and several contemporaneous accounts describe indigenous Caribbean islanders using manchineel’s toxic sap as an arrow poison.¹⁰

Eating manchineel fruit is known to cause abdominal pain, burning sensations in the oropharynx, and esophageal spasms.¹¹ Several case reports mention that consuming the fruit can create an exaggerated parasympathomimetic syndrome due to suspected anticholinesteraselike compounds.^3,11,12 Ophthalmologic injuries include severe conjunctivitis—sometimes extensive enough to cause superficial punctate epithelial keratitis.⁵ Dermatologic injuries have been described, but reports on its histopathologic features are limited. We present a case of manchineel dermatitis in a patient who subsequently underwent a skin biopsy.

Case Report

A 64-year-old physician (S.A.N.) came across a stand of manchineel trees while camping in the Virgin Islands National Park on St. John in the US Virgin Islands (Figure 1). The patient—who was knowledgeable about tropical ecology and was familiar with the tree—was curious about its purported cutaneous toxicity and applied the viscous white sap of a broken branchlet (Figure 2) to a patch of skin measuring 4 cm in diameter on the medial left calf. He took serial photographs of the site on days 2, 4 (Figure 3), 6, and 10 (Figure 4), showing the onset of erythema and the subsequent development of follicular pustules. On day 6, a 4-mm punch biopsy specimen was taken of the most prominent pustule. Histopathology showed a subcorneal acantholytic blister and epidermal spongiosis overlying a mixed perivascular infiltrate and follicular necrosis, which was consistent with irritant contact dermatitis (Figure 5). On day 8, the region became indurated and tender to pressure; however, there was no warmth, edema, purulent drainage, lymphangitic streaks, or other signs of infection. The region was never itchy; it was uncomfortable only with firm direct pressure. The patient applied hot compresses to the site for 10 minutes 1 to 2 times daily for roughly 2 weeks, and the affected area healed fully (without any additional intervention) in approximately 6 weeks.

Comment

Manchineel is a member of the Euphorbiaceae (also known as the euphorb or spurge) family, a mainly tropical or subtropical plant family that includes many useful as well as many toxic species. Examples of useful plants include cassava (Manihot esculenta) and the rubber tree (Hevea brasiliensis). Many euphorbs have well-described toxicities, and many (eg, castor bean, Ricinus communis) are useful in some circumstances and toxic in others.^6,12-14 Many euphorbs are known to cause skin reactions, usually due to toxins in the milky sap that directly irritate the skin or to latex compounds that can induce IgE-mediated contact dermatitis.^9,14

Manchineel contains a complex mix of toxins, though no specific one has been identified as the main cause of the associated irritant contact dermatitis. Manchineel sap (and sap of many other euphorbs) contains phorbol esters that may cause direct pH-induced cytotoxicity leading to keratinocyte necrosis. Diterpenes may augment this cytotoxic effect via induction of proinflammatory cytokines.¹² Pitts et al⁵ pointed to a mixture of oxygenated diterpene esters as the primary cause of toxicity and suggested that their water solubility explained occurrences of keratoconjunctivitis after contact with rainwater or dew from the manchineel tree.

All parts of the manchineel tree—fruit, leaves, wood, and sap—are poisonous. In a retrospective series of 97 cases of manchineel fruit ingestion, the most common symptoms were oropharyngeal pain (68% [66/97]), abdominal pain (42% [41/97]), and diarrhea (37% [36/97]). The same series identified 1 (1%) case of bradycardia and hypotension.³ Contact with the wood, exposure to sawdust, and inhalation of smoke from burning the wood can irritate the skin, conjunctivae, or nasopharynx. Rainwater or dew dripping from the leaves onto the skin can cause dermatitis and ophthalmitis, even without direct contact with the tree.^4,5

Management—There is no specific treatment for manchineel dermatitis. Because it is an irritant reaction and not a type IV hypersensitivity reaction, topical corticosteroids have minimal benefit. A regimen consisting of a thorough cleansing, wet compresses, and observation, as most symptoms resolve spontaneously within a few days, has been recommended.⁴ Our patient used hot compresses, which he believes helped heal the site, although his symptoms lasted for several weeks.

Given that there is no specific treatment for manchineel dermatitis, the wisest approach is strict avoidance. On many Caribbean islands, visitors are warned about the manchineel tree, advised to avoid direct contact, and reminded to avoid standing beneath it during a rainstorm (Figure 6).

Conclusion

This article begins with a question: “What is the world’s most dangerous tree?” Many sources from the indexed medical literature as well as the popular press and social media state that it is the manchineel. Although all parts of the manchineel tree are highly toxic, human exposures are uncommon, and deaths are more apocryphal than actual.

What is the world’s most dangerous tree? According to Guinness World Records¹ (and one unlucky contestant on the wilderness survival reality show Naked and Afraid,² who got its sap in his eyes and needed to be evacuated for treatment), the manchineel tree (Hippomane mancinella) has earned this designation.^1-3 Manchineel trees are part of the strand vegetation of islands in the West Indies and along the Caribbean coasts of South and Central America, where their copious root systems help reduce coastal erosion. In the United States, this poisonous tree grows along the southern edge of Florida’s Everglades National Park; the Florida Keys; and the US Virgin Islands, especially Virgin Islands National Park. Although the manchineel tree appears on several endangered species lists,^4-6 there are places within its distribution where it is locally abundant and thus poses a risk to residents and visitors.

The first European description of manchineel toxicity was by Peter Martyr d’Anghiera, a court historian and geographer of Christopher Columbus’s patroness, Isabella I, Queen of Castile and Léon. In the early 1500s, Peter Martyr wrote that on Columbus’s second New World voyage in 1493, the crew encountered a mysterious tree that burned the skin and eyes of anyone who had contact with it.⁷ Columbus called the tree’s fruit manzanilla de la muerte (“little apple of death”) after several sailors became severely ill from eating the fruit.^8,9 Manchineel lore is rife with tales of agonizing death after eating the applelike fruit, and several contemporaneous accounts describe indigenous Caribbean islanders using manchineel’s toxic sap as an arrow poison.¹⁰

Eating manchineel fruit is known to cause abdominal pain, burning sensations in the oropharynx, and esophageal spasms.¹¹ Several case reports mention that consuming the fruit can create an exaggerated parasympathomimetic syndrome due to suspected anticholinesteraselike compounds.^3,11,12 Ophthalmologic injuries include severe conjunctivitis—sometimes extensive enough to cause superficial punctate epithelial keratitis.⁵ Dermatologic injuries have been described, but reports on its histopathologic features are limited. We present a case of manchineel dermatitis in a patient who subsequently underwent a skin biopsy.

Case Report

A 64-year-old physician (S.A.N.) came across a stand of manchineel trees while camping in the Virgin Islands National Park on St. John in the US Virgin Islands (Figure 1). The patient—who was knowledgeable about tropical ecology and was familiar with the tree—was curious about its purported cutaneous toxicity and applied the viscous white sap of a broken branchlet (Figure 2) to a patch of skin measuring 4 cm in diameter on the medial left calf. He took serial photographs of the site on days 2, 4 (Figure 3), 6, and 10 (Figure 4), showing the onset of erythema and the subsequent development of follicular pustules. On day 6, a 4-mm punch biopsy specimen was taken of the most prominent pustule. Histopathology showed a subcorneal acantholytic blister and epidermal spongiosis overlying a mixed perivascular infiltrate and follicular necrosis, which was consistent with irritant contact dermatitis (Figure 5). On day 8, the region became indurated and tender to pressure; however, there was no warmth, edema, purulent drainage, lymphangitic streaks, or other signs of infection. The region was never itchy; it was uncomfortable only with firm direct pressure. The patient applied hot compresses to the site for 10 minutes 1 to 2 times daily for roughly 2 weeks, and the affected area healed fully (without any additional intervention) in approximately 6 weeks.

Comment

Manchineel is a member of the Euphorbiaceae (also known as the euphorb or spurge) family, a mainly tropical or subtropical plant family that includes many useful as well as many toxic species. Examples of useful plants include cassava (Manihot esculenta) and the rubber tree (Hevea brasiliensis). Many euphorbs have well-described toxicities, and many (eg, castor bean, Ricinus communis) are useful in some circumstances and toxic in others.^6,12-14 Many euphorbs are known to cause skin reactions, usually due to toxins in the milky sap that directly irritate the skin or to latex compounds that can induce IgE-mediated contact dermatitis.^9,14

Manchineel contains a complex mix of toxins, though no specific one has been identified as the main cause of the associated irritant contact dermatitis. Manchineel sap (and sap of many other euphorbs) contains phorbol esters that may cause direct pH-induced cytotoxicity leading to keratinocyte necrosis. Diterpenes may augment this cytotoxic effect via induction of proinflammatory cytokines.¹² Pitts et al⁵ pointed to a mixture of oxygenated diterpene esters as the primary cause of toxicity and suggested that their water solubility explained occurrences of keratoconjunctivitis after contact with rainwater or dew from the manchineel tree.

All parts of the manchineel tree—fruit, leaves, wood, and sap—are poisonous. In a retrospective series of 97 cases of manchineel fruit ingestion, the most common symptoms were oropharyngeal pain (68% [66/97]), abdominal pain (42% [41/97]), and diarrhea (37% [36/97]). The same series identified 1 (1%) case of bradycardia and hypotension.³ Contact with the wood, exposure to sawdust, and inhalation of smoke from burning the wood can irritate the skin, conjunctivae, or nasopharynx. Rainwater or dew dripping from the leaves onto the skin can cause dermatitis and ophthalmitis, even without direct contact with the tree.^4,5

Management—There is no specific treatment for manchineel dermatitis. Because it is an irritant reaction and not a type IV hypersensitivity reaction, topical corticosteroids have minimal benefit. A regimen consisting of a thorough cleansing, wet compresses, and observation, as most symptoms resolve spontaneously within a few days, has been recommended.⁴ Our patient used hot compresses, which he believes helped heal the site, although his symptoms lasted for several weeks.

Given that there is no specific treatment for manchineel dermatitis, the wisest approach is strict avoidance. On many Caribbean islands, visitors are warned about the manchineel tree, advised to avoid direct contact, and reminded to avoid standing beneath it during a rainstorm (Figure 6).

Conclusion

This article begins with a question: “What is the world’s most dangerous tree?” Many sources from the indexed medical literature as well as the popular press and social media state that it is the manchineel. Although all parts of the manchineel tree are highly toxic, human exposures are uncommon, and deaths are more apocryphal than actual.