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The Diagnosis: Erythema Ab Igne

Given the patient's reticulated hyperpigmented lesions in the setting of recent space heater use with heater closer to the more affected leg, erythema ab igne was diagnosed. Patient education was provided and moving the heater away from the lower extremities was advised.

Erythema ab igne first was described by German dermatologist Abraham Buschke as hitze melanose, meaning melanosis induced by heat. The classic skin findings were first observed on the lower legs of patients who worked in front of open fires or coal stoves.¹ Over the years, new causes of erythema ab igne secondary to prolonged thermal radiation exposure have been reported.¹ In the elderly, hospitalized, and chronic pain patients, erythema ab igne has been observed in areas treated with heating pads and blankets.² Other triggers such as frequent hot bathing, furniture, steam radiators, space heaters, and laptops also have been reported.^3-6 Laptop-induced erythema ab igne is a diagnosis that has been reported in the last decade and its incidence likely will increase in the future.⁶

The clinical manifestations of erythema ab igne correlate with the frequency and duration of heat exposure. Acutely, a mild and transient erythema develops in the affected area. With chronic heat exposure, these areas subsequently develop a permanent reticulated hyperpigmented pattern and may eventually become atrophic.^2,6 All body surfaces are at risk, but erythema ab igne classically involves the legs, lower back, and/or abdomen. Lesions typically are asymptomatic; however, burning and pruritus can be present.^2,6 Bullous erythema ab igne, though rare, has been reported,⁷ suggesting a potential transition from erythema ab igne to burns.⁶

Biopsy is not recommended for diagnosis; however, the histopathologic changes of erythema ab igne include hyperkeratosis, interface dermatitis, epidermal atrophy with apoptotic keratinocytes, and melanin incontinence. Although this condition typically is benign, histologic findings could resemble actinic keratosis, suggesting that chronic changes induced by infrared thermal radiation may lead to squamous cell carcinoma or rarely Merkel cell carcinoma. The latency for developing carcinoma appears to extend 30 years, with a 30% tendency for recurrence or metastasis. Given the possibility of an increase in erythema ab igne in the pediatric population in the upcoming years, as displayed by our patient, and increasing laptop and electronic use in children and adolescents, it is important to be aware of this skin condition and the potential complications of it going undiagnosed.^2,6

No specific therapy for erythema ab igne exists. Treatment is centered on eliminating exposure to the heat source. With appropriate removal, the reticulated hyperpigmented lesions will resolve, sometimes taking several months.

Differential diagnosis includes livedo reticularis, livedoid vasculopathy, and cutis marmorata. The reticulated purpuric lesions of livedo reticularis involving the extremities often mimic erythema ab igne's cutaneous morphology; however, livedo reticularis frequently is associated with conditions such as drug reactions, infections, thrombosis, and vasculitides,² as opposed to erythema ab igne, which frequently is associated with conditions causing pain or decreased body temperature, thus necessitating use of heating devices, as seen in our patient. Livedoid vasculopathy is characterized by purpuric macules involving the lower legs and feet that progress to recurrent leg ulcers. Our patient's asymptomatic lesions and absence of ulcers excluded this diagnosis.⁸ Lastly, cutis marmorata, a congenital condition, is characterized by blue-violet vascular networks that often display ulceration and atrophy of the involved skin as well as hypertrophy or atrophy of the involved limb⁹; these clinical findings were not present in our patient and this diagnosis would not explain the relationship between the cutaneous lesions and heat exposure. 

The Diagnosis: Erythema Ab Igne

Given the patient's reticulated hyperpigmented lesions in the setting of recent space heater use with heater closer to the more affected leg, erythema ab igne was diagnosed. Patient education was provided and moving the heater away from the lower extremities was advised.

Erythema ab igne first was described by German dermatologist Abraham Buschke as hitze melanose, meaning melanosis induced by heat. The classic skin findings were first observed on the lower legs of patients who worked in front of open fires or coal stoves.¹ Over the years, new causes of erythema ab igne secondary to prolonged thermal radiation exposure have been reported.¹ In the elderly, hospitalized, and chronic pain patients, erythema ab igne has been observed in areas treated with heating pads and blankets.² Other triggers such as frequent hot bathing, furniture, steam radiators, space heaters, and laptops also have been reported.^3-6 Laptop-induced erythema ab igne is a diagnosis that has been reported in the last decade and its incidence likely will increase in the future.⁶

The clinical manifestations of erythema ab igne correlate with the frequency and duration of heat exposure. Acutely, a mild and transient erythema develops in the affected area. With chronic heat exposure, these areas subsequently develop a permanent reticulated hyperpigmented pattern and may eventually become atrophic.^2,6 All body surfaces are at risk, but erythema ab igne classically involves the legs, lower back, and/or abdomen. Lesions typically are asymptomatic; however, burning and pruritus can be present.^2,6 Bullous erythema ab igne, though rare, has been reported,⁷ suggesting a potential transition from erythema ab igne to burns.⁶

Biopsy is not recommended for diagnosis; however, the histopathologic changes of erythema ab igne include hyperkeratosis, interface dermatitis, epidermal atrophy with apoptotic keratinocytes, and melanin incontinence. Although this condition typically is benign, histologic findings could resemble actinic keratosis, suggesting that chronic changes induced by infrared thermal radiation may lead to squamous cell carcinoma or rarely Merkel cell carcinoma. The latency for developing carcinoma appears to extend 30 years, with a 30% tendency for recurrence or metastasis. Given the possibility of an increase in erythema ab igne in the pediatric population in the upcoming years, as displayed by our patient, and increasing laptop and electronic use in children and adolescents, it is important to be aware of this skin condition and the potential complications of it going undiagnosed.^2,6

No specific therapy for erythema ab igne exists. Treatment is centered on eliminating exposure to the heat source. With appropriate removal, the reticulated hyperpigmented lesions will resolve, sometimes taking several months.

Differential diagnosis includes livedo reticularis, livedoid vasculopathy, and cutis marmorata. The reticulated purpuric lesions of livedo reticularis involving the extremities often mimic erythema ab igne's cutaneous morphology; however, livedo reticularis frequently is associated with conditions such as drug reactions, infections, thrombosis, and vasculitides,² as opposed to erythema ab igne, which frequently is associated with conditions causing pain or decreased body temperature, thus necessitating use of heating devices, as seen in our patient. Livedoid vasculopathy is characterized by purpuric macules involving the lower legs and feet that progress to recurrent leg ulcers. Our patient's asymptomatic lesions and absence of ulcers excluded this diagnosis.⁸ Lastly, cutis marmorata, a congenital condition, is characterized by blue-violet vascular networks that often display ulceration and atrophy of the involved skin as well as hypertrophy or atrophy of the involved limb⁹; these clinical findings were not present in our patient and this diagnosis would not explain the relationship between the cutaneous lesions and heat exposure. 

The Diagnosis: Erythema Ab Igne

Given the patient's reticulated hyperpigmented lesions in the setting of recent space heater use with heater closer to the more affected leg, erythema ab igne was diagnosed. Patient education was provided and moving the heater away from the lower extremities was advised.

Erythema ab igne first was described by German dermatologist Abraham Buschke as hitze melanose, meaning melanosis induced by heat. The classic skin findings were first observed on the lower legs of patients who worked in front of open fires or coal stoves.¹ Over the years, new causes of erythema ab igne secondary to prolonged thermal radiation exposure have been reported.¹ In the elderly, hospitalized, and chronic pain patients, erythema ab igne has been observed in areas treated with heating pads and blankets.² Other triggers such as frequent hot bathing, furniture, steam radiators, space heaters, and laptops also have been reported.^3-6 Laptop-induced erythema ab igne is a diagnosis that has been reported in the last decade and its incidence likely will increase in the future.⁶

The clinical manifestations of erythema ab igne correlate with the frequency and duration of heat exposure. Acutely, a mild and transient erythema develops in the affected area. With chronic heat exposure, these areas subsequently develop a permanent reticulated hyperpigmented pattern and may eventually become atrophic.^2,6 All body surfaces are at risk, but erythema ab igne classically involves the legs, lower back, and/or abdomen. Lesions typically are asymptomatic; however, burning and pruritus can be present.^2,6 Bullous erythema ab igne, though rare, has been reported,⁷ suggesting a potential transition from erythema ab igne to burns.⁶

Biopsy is not recommended for diagnosis; however, the histopathologic changes of erythema ab igne include hyperkeratosis, interface dermatitis, epidermal atrophy with apoptotic keratinocytes, and melanin incontinence. Although this condition typically is benign, histologic findings could resemble actinic keratosis, suggesting that chronic changes induced by infrared thermal radiation may lead to squamous cell carcinoma or rarely Merkel cell carcinoma. The latency for developing carcinoma appears to extend 30 years, with a 30% tendency for recurrence or metastasis. Given the possibility of an increase in erythema ab igne in the pediatric population in the upcoming years, as displayed by our patient, and increasing laptop and electronic use in children and adolescents, it is important to be aware of this skin condition and the potential complications of it going undiagnosed.^2,6

No specific therapy for erythema ab igne exists. Treatment is centered on eliminating exposure to the heat source. With appropriate removal, the reticulated hyperpigmented lesions will resolve, sometimes taking several months.

Differential diagnosis includes livedo reticularis, livedoid vasculopathy, and cutis marmorata. The reticulated purpuric lesions of livedo reticularis involving the extremities often mimic erythema ab igne's cutaneous morphology; however, livedo reticularis frequently is associated with conditions such as drug reactions, infections, thrombosis, and vasculitides,² as opposed to erythema ab igne, which frequently is associated with conditions causing pain or decreased body temperature, thus necessitating use of heating devices, as seen in our patient. Livedoid vasculopathy is characterized by purpuric macules involving the lower legs and feet that progress to recurrent leg ulcers. Our patient's asymptomatic lesions and absence of ulcers excluded this diagnosis.⁸ Lastly, cutis marmorata, a congenital condition, is characterized by blue-violet vascular networks that often display ulceration and atrophy of the involved skin as well as hypertrophy or atrophy of the involved limb⁹; these clinical findings were not present in our patient and this diagnosis would not explain the relationship between the cutaneous lesions and heat exposure. 

The Diagnosis: Blue Toe Syndrome

The clinical manifestation suggested blue toe syndrome. A variety of causes for blue toe syndrome are known such as embolism, thrombosis, vasoconstrictive disorders, infectious and noninfectious inflammation, extensive venous thrombosis, and abnormal circulating blood.¹ Among them, only emboli from atherosclerotic plaques give rise to typical cholesterol clefts on skin biopsy (Figure 1). Such atheroemboli often are an iatrogenic complication, especially those caused by invasive percutaneous procedures or damage to the arterial walls from vascular surgery. However, spontaneous plaque hemorrhage or shearing forces of the circulating blood can disrupt atheromatous plaques and cause embolization of the cholesterol crystals, which was likely to be the case in our patient because no preceding trigger events were noted.

Other clinical features also are seen in atheroembolism. Approximately half of patients with atheroembolism develop clinical kidney disease.² Almost all iatrogenic cases have acute or subacute reduction in glomerular filtration rate of at least to 50% level, whereas the spontaneous cases present as stable chronic renal failure.³ Approximately 20% of patients with atheroembolism also have involvement of digestive organs.^4,5 Abdominal pain, diarrhea, and gastrointestinal blood loss are common features; bowel infarction and perforation occasionally occur.⁵ Pancreatitis is another common complication, and serum amylase levels are raised in approximately 50% of patients.6 Atheroemboli may reach the eyes and brain. They occasionally can cause loss of vision,⁷ as well as transient ischemic attacks, strokes, and gradual deterioration in cerebral function.³ Blood eosinophilia, which occurs in approximately 60% of patients, is an important finding.^3,8

Although there is no specific therapy for atheroembolism, the use of antiplatelet agents is considered reasonable because they are beneficial in preventing myocardial infarction in patients with atherosclerosis.⁹ In our case, the livedo reticularis cleared, as did the coldness on the affected toes after 2 weeks of sarpogrelate hydrochloride administration; however, development of necrotic change was noted (Figure 2). Necrotic change on the hallux disappeared after 2 weeks.

The Diagnosis: Blue Toe Syndrome

The clinical manifestation suggested blue toe syndrome. A variety of causes for blue toe syndrome are known such as embolism, thrombosis, vasoconstrictive disorders, infectious and noninfectious inflammation, extensive venous thrombosis, and abnormal circulating blood.¹ Among them, only emboli from atherosclerotic plaques give rise to typical cholesterol clefts on skin biopsy (Figure 1). Such atheroemboli often are an iatrogenic complication, especially those caused by invasive percutaneous procedures or damage to the arterial walls from vascular surgery. However, spontaneous plaque hemorrhage or shearing forces of the circulating blood can disrupt atheromatous plaques and cause embolization of the cholesterol crystals, which was likely to be the case in our patient because no preceding trigger events were noted.

Other clinical features also are seen in atheroembolism. Approximately half of patients with atheroembolism develop clinical kidney disease.² Almost all iatrogenic cases have acute or subacute reduction in glomerular filtration rate of at least to 50% level, whereas the spontaneous cases present as stable chronic renal failure.³ Approximately 20% of patients with atheroembolism also have involvement of digestive organs.^4,5 Abdominal pain, diarrhea, and gastrointestinal blood loss are common features; bowel infarction and perforation occasionally occur.⁵ Pancreatitis is another common complication, and serum amylase levels are raised in approximately 50% of patients.6 Atheroemboli may reach the eyes and brain. They occasionally can cause loss of vision,⁷ as well as transient ischemic attacks, strokes, and gradual deterioration in cerebral function.³ Blood eosinophilia, which occurs in approximately 60% of patients, is an important finding.^3,8

Although there is no specific therapy for atheroembolism, the use of antiplatelet agents is considered reasonable because they are beneficial in preventing myocardial infarction in patients with atherosclerosis.⁹ In our case, the livedo reticularis cleared, as did the coldness on the affected toes after 2 weeks of sarpogrelate hydrochloride administration; however, development of necrotic change was noted (Figure 2). Necrotic change on the hallux disappeared after 2 weeks.

The Diagnosis: Blue Toe Syndrome

The clinical manifestation suggested blue toe syndrome. A variety of causes for blue toe syndrome are known such as embolism, thrombosis, vasoconstrictive disorders, infectious and noninfectious inflammation, extensive venous thrombosis, and abnormal circulating blood.¹ Among them, only emboli from atherosclerotic plaques give rise to typical cholesterol clefts on skin biopsy (Figure 1). Such atheroemboli often are an iatrogenic complication, especially those caused by invasive percutaneous procedures or damage to the arterial walls from vascular surgery. However, spontaneous plaque hemorrhage or shearing forces of the circulating blood can disrupt atheromatous plaques and cause embolization of the cholesterol crystals, which was likely to be the case in our patient because no preceding trigger events were noted.

Other clinical features also are seen in atheroembolism. Approximately half of patients with atheroembolism develop clinical kidney disease.² Almost all iatrogenic cases have acute or subacute reduction in glomerular filtration rate of at least to 50% level, whereas the spontaneous cases present as stable chronic renal failure.³ Approximately 20% of patients with atheroembolism also have involvement of digestive organs.^4,5 Abdominal pain, diarrhea, and gastrointestinal blood loss are common features; bowel infarction and perforation occasionally occur.⁵ Pancreatitis is another common complication, and serum amylase levels are raised in approximately 50% of patients.6 Atheroemboli may reach the eyes and brain. They occasionally can cause loss of vision,⁷ as well as transient ischemic attacks, strokes, and gradual deterioration in cerebral function.³ Blood eosinophilia, which occurs in approximately 60% of patients, is an important finding.^3,8

Although there is no specific therapy for atheroembolism, the use of antiplatelet agents is considered reasonable because they are beneficial in preventing myocardial infarction in patients with atherosclerosis.⁹ In our case, the livedo reticularis cleared, as did the coldness on the affected toes after 2 weeks of sarpogrelate hydrochloride administration; however, development of necrotic change was noted (Figure 2). Necrotic change on the hallux disappeared after 2 weeks.

The Diagnosis: Secondary Syphilis

Syphilis, known as the great mimicker, has a wide-ranging clinical and histologic presentation. There can be overlapping features with many of the entities included in the differential diagnoses. As our patient exemplifies, clinicians and pathologists must have a high index of suspicion, and any concerning features should lead to a more in-depth patient history, spirochete stains, and serologic testing.

Our patient was seen by several dermatologists over the course of 2 years and therapy with topical steroids failed. He was eager to pursue more aggressive therapy with methotrexate, and a punch biopsy was performed to confirm the diagnosis of psoriasis prior to initiating treatment. Hematoxylin and eosin staining results on low power can be seen in Figure 1A. Medium-power view demonstrated vacuolar interface dermatitis (Figure 1B) with psoriasiform epidermal hyperplasia with slender elongation of rete ridges; neutrophils in the stratum corneum; endothelial cell swelling (Figure 1C); and mixed infiltrate with high plasma cells (Figure 1D), lymphocytes, and histiocytes. Although the biopsy results were psoriasiform, there was high suspicion for syphilis in this case. Additional staining for spirochetes was performed with syphilis immunohistochemical stain¹ (Figure 2), which revealed spirochetes present on the patient's biopsy, confirming the diagnosis of syphilis. Warthin-Starry stain also can be performed to confirm the diagnosis.

Based on histologic features, the differential diagnosis includes psoriasis vulgaris, eczema, lichen planus, or lichenoid drug eruption. Psoriasis vulgaris displays regular psoriasiform epidermal hyperplasia with hypergranulosis and confluent parakeratosis. The elongated rete pegs are broad rather than slender.² Neutrophils are present in the stratum corneum. In contrast, eczematous dermatitis is characterized by epidermal hyperplasia, spongiosis, parakeratosis, and eosinophils. Lichen planus classically displays a brisk bandlike lymphocytic infiltrate that closely abuts or obscures the dermoepidermal junction. Parakeratosis, neutrophils, and eosinophils should be absent. The rete pegs taper to a point, similar to a sawtooth, while they are long and slender with syphilis, similar to an ice pick. Although lichenoid drug eruption presents with interface dermatitis, parakeratosis, and eosinophils, the epidermis is hyperplastic without the slender elongation of rete pegs seen in syphilis.

Further workup with serologic testing demonstrated that the patient had a syphilis IgG titer of greater than 8.0 (reactive, >6.0), indicating the patient had been infected.³ Reactive syphilis IgG, a specific treponemal test, should be followed with a nontreponemal assay of either rapid plasma reagin (RPR) or VDRL test to confirm disease activity, according to recommendations from the Centers for Disease Control and Prevention,4 which represents a change to the traditional algorithm that called for screening with a nontreponemal test and confirming with a specific treponemal test. The patient had a positive RPR and quantitative RPR titer was found as 1:2048, indicating that syphilis was active or recently treated. Testing for human immunodeficiency virus (HIV) revealed a quantitative RNA polymerase chain reaction of 145,000 copies/mL and a CD4 count of 18 cells/µL (reference range, 533-1674 cells/µL).

The patient initially was treated for latent syphilis with 3 doses of intramuscular penicillin G benzathine 2.4 million U once weekly for 3 weeks. Due to his high RPR titers and low CD4 count, a lumbar puncture was later pursued, which revealed positive results from a cerebrospinal fluid (CSF)-VDRL test, confirming a diagnosis of neurosyphilis. Although a positive CSF-VDRL test is specific for the diagnosis of neurosyphilis, the sensitivity of the CSF-VDRL test against clinical diagnosis is only 30% to 70%.⁵ Intravenous aqueous penicillin G 4 million U every 4 hours was started for 14 days for neurosyphilis. One month following the completion of the intravenous penicillin, the rash completely resolved. The patient was in a 10-year monogamous relationship with a man and did not use condoms. Typically, signs and symptoms of secondary syphilis begin 4 to 10 weeks after the appearance of a chancre. However, the classic chancre of primary syphilis among men who have sex with men may go unnoticed in those who may not be able to see anal lesions.⁶ Also, infection with syphilis increases the likelihood of acquiring and transmitting HIV. All patients diagnosed with syphilis should have additional testing for HIV and other sexually transmitted diseases. 

For patients with a history of thick scaly plaques on the wrists, knees, and feet resistant to topical steroid therapy, dermatologists should maintain a high index of clinical suspicion for syphilis. 

The Diagnosis: Secondary Syphilis

Syphilis, known as the great mimicker, has a wide-ranging clinical and histologic presentation. There can be overlapping features with many of the entities included in the differential diagnoses. As our patient exemplifies, clinicians and pathologists must have a high index of suspicion, and any concerning features should lead to a more in-depth patient history, spirochete stains, and serologic testing.

Our patient was seen by several dermatologists over the course of 2 years and therapy with topical steroids failed. He was eager to pursue more aggressive therapy with methotrexate, and a punch biopsy was performed to confirm the diagnosis of psoriasis prior to initiating treatment. Hematoxylin and eosin staining results on low power can be seen in Figure 1A. Medium-power view demonstrated vacuolar interface dermatitis (Figure 1B) with psoriasiform epidermal hyperplasia with slender elongation of rete ridges; neutrophils in the stratum corneum; endothelial cell swelling (Figure 1C); and mixed infiltrate with high plasma cells (Figure 1D), lymphocytes, and histiocytes. Although the biopsy results were psoriasiform, there was high suspicion for syphilis in this case. Additional staining for spirochetes was performed with syphilis immunohistochemical stain¹ (Figure 2), which revealed spirochetes present on the patient's biopsy, confirming the diagnosis of syphilis. Warthin-Starry stain also can be performed to confirm the diagnosis.

Based on histologic features, the differential diagnosis includes psoriasis vulgaris, eczema, lichen planus, or lichenoid drug eruption. Psoriasis vulgaris displays regular psoriasiform epidermal hyperplasia with hypergranulosis and confluent parakeratosis. The elongated rete pegs are broad rather than slender.² Neutrophils are present in the stratum corneum. In contrast, eczematous dermatitis is characterized by epidermal hyperplasia, spongiosis, parakeratosis, and eosinophils. Lichen planus classically displays a brisk bandlike lymphocytic infiltrate that closely abuts or obscures the dermoepidermal junction. Parakeratosis, neutrophils, and eosinophils should be absent. The rete pegs taper to a point, similar to a sawtooth, while they are long and slender with syphilis, similar to an ice pick. Although lichenoid drug eruption presents with interface dermatitis, parakeratosis, and eosinophils, the epidermis is hyperplastic without the slender elongation of rete pegs seen in syphilis.

Further workup with serologic testing demonstrated that the patient had a syphilis IgG titer of greater than 8.0 (reactive, >6.0), indicating the patient had been infected.³ Reactive syphilis IgG, a specific treponemal test, should be followed with a nontreponemal assay of either rapid plasma reagin (RPR) or VDRL test to confirm disease activity, according to recommendations from the Centers for Disease Control and Prevention,4 which represents a change to the traditional algorithm that called for screening with a nontreponemal test and confirming with a specific treponemal test. The patient had a positive RPR and quantitative RPR titer was found as 1:2048, indicating that syphilis was active or recently treated. Testing for human immunodeficiency virus (HIV) revealed a quantitative RNA polymerase chain reaction of 145,000 copies/mL and a CD4 count of 18 cells/µL (reference range, 533-1674 cells/µL).

The patient initially was treated for latent syphilis with 3 doses of intramuscular penicillin G benzathine 2.4 million U once weekly for 3 weeks. Due to his high RPR titers and low CD4 count, a lumbar puncture was later pursued, which revealed positive results from a cerebrospinal fluid (CSF)-VDRL test, confirming a diagnosis of neurosyphilis. Although a positive CSF-VDRL test is specific for the diagnosis of neurosyphilis, the sensitivity of the CSF-VDRL test against clinical diagnosis is only 30% to 70%.⁵ Intravenous aqueous penicillin G 4 million U every 4 hours was started for 14 days for neurosyphilis. One month following the completion of the intravenous penicillin, the rash completely resolved. The patient was in a 10-year monogamous relationship with a man and did not use condoms. Typically, signs and symptoms of secondary syphilis begin 4 to 10 weeks after the appearance of a chancre. However, the classic chancre of primary syphilis among men who have sex with men may go unnoticed in those who may not be able to see anal lesions.⁶ Also, infection with syphilis increases the likelihood of acquiring and transmitting HIV. All patients diagnosed with syphilis should have additional testing for HIV and other sexually transmitted diseases. 

For patients with a history of thick scaly plaques on the wrists, knees, and feet resistant to topical steroid therapy, dermatologists should maintain a high index of clinical suspicion for syphilis. 

The Diagnosis: Secondary Syphilis

Syphilis, known as the great mimicker, has a wide-ranging clinical and histologic presentation. There can be overlapping features with many of the entities included in the differential diagnoses. As our patient exemplifies, clinicians and pathologists must have a high index of suspicion, and any concerning features should lead to a more in-depth patient history, spirochete stains, and serologic testing.

Our patient was seen by several dermatologists over the course of 2 years and therapy with topical steroids failed. He was eager to pursue more aggressive therapy with methotrexate, and a punch biopsy was performed to confirm the diagnosis of psoriasis prior to initiating treatment. Hematoxylin and eosin staining results on low power can be seen in Figure 1A. Medium-power view demonstrated vacuolar interface dermatitis (Figure 1B) with psoriasiform epidermal hyperplasia with slender elongation of rete ridges; neutrophils in the stratum corneum; endothelial cell swelling (Figure 1C); and mixed infiltrate with high plasma cells (Figure 1D), lymphocytes, and histiocytes. Although the biopsy results were psoriasiform, there was high suspicion for syphilis in this case. Additional staining for spirochetes was performed with syphilis immunohistochemical stain¹ (Figure 2), which revealed spirochetes present on the patient's biopsy, confirming the diagnosis of syphilis. Warthin-Starry stain also can be performed to confirm the diagnosis.

Based on histologic features, the differential diagnosis includes psoriasis vulgaris, eczema, lichen planus, or lichenoid drug eruption. Psoriasis vulgaris displays regular psoriasiform epidermal hyperplasia with hypergranulosis and confluent parakeratosis. The elongated rete pegs are broad rather than slender.² Neutrophils are present in the stratum corneum. In contrast, eczematous dermatitis is characterized by epidermal hyperplasia, spongiosis, parakeratosis, and eosinophils. Lichen planus classically displays a brisk bandlike lymphocytic infiltrate that closely abuts or obscures the dermoepidermal junction. Parakeratosis, neutrophils, and eosinophils should be absent. The rete pegs taper to a point, similar to a sawtooth, while they are long and slender with syphilis, similar to an ice pick. Although lichenoid drug eruption presents with interface dermatitis, parakeratosis, and eosinophils, the epidermis is hyperplastic without the slender elongation of rete pegs seen in syphilis.

Further workup with serologic testing demonstrated that the patient had a syphilis IgG titer of greater than 8.0 (reactive, >6.0), indicating the patient had been infected.³ Reactive syphilis IgG, a specific treponemal test, should be followed with a nontreponemal assay of either rapid plasma reagin (RPR) or VDRL test to confirm disease activity, according to recommendations from the Centers for Disease Control and Prevention,4 which represents a change to the traditional algorithm that called for screening with a nontreponemal test and confirming with a specific treponemal test. The patient had a positive RPR and quantitative RPR titer was found as 1:2048, indicating that syphilis was active or recently treated. Testing for human immunodeficiency virus (HIV) revealed a quantitative RNA polymerase chain reaction of 145,000 copies/mL and a CD4 count of 18 cells/µL (reference range, 533-1674 cells/µL).

The patient initially was treated for latent syphilis with 3 doses of intramuscular penicillin G benzathine 2.4 million U once weekly for 3 weeks. Due to his high RPR titers and low CD4 count, a lumbar puncture was later pursued, which revealed positive results from a cerebrospinal fluid (CSF)-VDRL test, confirming a diagnosis of neurosyphilis. Although a positive CSF-VDRL test is specific for the diagnosis of neurosyphilis, the sensitivity of the CSF-VDRL test against clinical diagnosis is only 30% to 70%.⁵ Intravenous aqueous penicillin G 4 million U every 4 hours was started for 14 days for neurosyphilis. One month following the completion of the intravenous penicillin, the rash completely resolved. The patient was in a 10-year monogamous relationship with a man and did not use condoms. Typically, signs and symptoms of secondary syphilis begin 4 to 10 weeks after the appearance of a chancre. However, the classic chancre of primary syphilis among men who have sex with men may go unnoticed in those who may not be able to see anal lesions.⁶ Also, infection with syphilis increases the likelihood of acquiring and transmitting HIV. All patients diagnosed with syphilis should have additional testing for HIV and other sexually transmitted diseases. 

For patients with a history of thick scaly plaques on the wrists, knees, and feet resistant to topical steroid therapy, dermatologists should maintain a high index of clinical suspicion for syphilis. 

The Diagnosis: Livedoid Vasculopathy

Livedoid vasculopathy (LV) is a rare cutaneous disorder that most commonly affects the lower legs. It has an estimated incidence of 1 case per 100,000 per year and predominantly affects women.¹ The disease pathogenesis is not fully understood but is thought to involve thrombosis and occlusion of dermal vessels resulting in tissue hypoxia.² Both inherited and acquired thrombophilic conditions frequently are seen in patients with LV.^3,4 Livedoid vasculopathy also has been described as idiopathic⁵ and is associated with immune complex deposition.⁶ However, the number of cases of idiopathic LV may be overestimated; as technological advancements to detect coagulation abnormalities improve, it is hypothesized that this entity will be identified less often.^2,4

Livedoid vasculopathy has been described in the literature using the term PPURPLE (painful purpuric ulcers with reticular pattern of lower extremities).⁷ The triad of livedo racemosa, recurrent painful ulcerations, and residual healing with atrophie blanche characterizes the clinical manifestations of LV; however, all 3 characteristics do not need to appear simultaneously for a diagnosis to be made. The condition has a chronic course with spontaneous remissions and exacerbations. Episodic ulcerations occur, especially in the summertime, and heal slowly, leaving behind atrophic, porcelain white, stellate-shaped scars called atrophie blanche. Livedo racemosa also may be seen in Sneddon syndrome; however, these patients experience neurologic symptoms secondary to cerebrovascular occlusion. In contrast to livedo racemosa, acquired livedo reticularis represents a physiologic hypoperfusion pattern that occurs in response to cold exposure.⁸ A localized sharp pain, known as angina cutis, typically precedes the clinical symptom of painful ulcerations.⁹ Atrophie blanche once was thought to be specific to LV but has been seen in other diseases such as systemic lupus erythematosus and chronic venous insufficiency.²

The diagnosis of LV is based on identification of characteristic clinical features and skin biopsy. In almost all biopsy specimens, histopathology reveals fibrinoid occlusion of vessels in the superficial and mid dermis.⁴ Other findings may include epidermal necrosis and vessel wall hyalinization and infarction² (Figure). Because LV is commonly misdiagnosed as vasculitis, the absence of hallmark features of vasculitis such as neutrophilic infiltrate of blood vessel walls and fibrinoid necrosis suggest the diagnosis. Extensive laboratory evaluation for inherited and acquired coagulation abnormalities should be performed.

Treatment of LV is difficult, as there is currently no consensus on optimal therapy. The mainstay of therapy is to reduce pain, prevent infection, and reduce ulceration and development of atrophie blanche. Underlying causes should be identified and appropriately treated. Because the primary pathogenesis of LV is considered to be a hypercoagulable state, first-line treatment often includes therapies to enhance blood flow and prevent thrombosis such as smoking cessation, antiplatelet therapy, and pentoxifylline. Vasodilating agents, anti-inflammatory agents, anticoagulation, and fibrinolytic therapy also have been used with varying degrees of success.⁷

The Diagnosis: Livedoid Vasculopathy

Livedoid vasculopathy (LV) is a rare cutaneous disorder that most commonly affects the lower legs. It has an estimated incidence of 1 case per 100,000 per year and predominantly affects women.¹ The disease pathogenesis is not fully understood but is thought to involve thrombosis and occlusion of dermal vessels resulting in tissue hypoxia.² Both inherited and acquired thrombophilic conditions frequently are seen in patients with LV.^3,4 Livedoid vasculopathy also has been described as idiopathic⁵ and is associated with immune complex deposition.⁶ However, the number of cases of idiopathic LV may be overestimated; as technological advancements to detect coagulation abnormalities improve, it is hypothesized that this entity will be identified less often.^2,4

Livedoid vasculopathy has been described in the literature using the term PPURPLE (painful purpuric ulcers with reticular pattern of lower extremities).⁷ The triad of livedo racemosa, recurrent painful ulcerations, and residual healing with atrophie blanche characterizes the clinical manifestations of LV; however, all 3 characteristics do not need to appear simultaneously for a diagnosis to be made. The condition has a chronic course with spontaneous remissions and exacerbations. Episodic ulcerations occur, especially in the summertime, and heal slowly, leaving behind atrophic, porcelain white, stellate-shaped scars called atrophie blanche. Livedo racemosa also may be seen in Sneddon syndrome; however, these patients experience neurologic symptoms secondary to cerebrovascular occlusion. In contrast to livedo racemosa, acquired livedo reticularis represents a physiologic hypoperfusion pattern that occurs in response to cold exposure.⁸ A localized sharp pain, known as angina cutis, typically precedes the clinical symptom of painful ulcerations.⁹ Atrophie blanche once was thought to be specific to LV but has been seen in other diseases such as systemic lupus erythematosus and chronic venous insufficiency.²

The diagnosis of LV is based on identification of characteristic clinical features and skin biopsy. In almost all biopsy specimens, histopathology reveals fibrinoid occlusion of vessels in the superficial and mid dermis.⁴ Other findings may include epidermal necrosis and vessel wall hyalinization and infarction² (Figure). Because LV is commonly misdiagnosed as vasculitis, the absence of hallmark features of vasculitis such as neutrophilic infiltrate of blood vessel walls and fibrinoid necrosis suggest the diagnosis. Extensive laboratory evaluation for inherited and acquired coagulation abnormalities should be performed.

Treatment of LV is difficult, as there is currently no consensus on optimal therapy. The mainstay of therapy is to reduce pain, prevent infection, and reduce ulceration and development of atrophie blanche. Underlying causes should be identified and appropriately treated. Because the primary pathogenesis of LV is considered to be a hypercoagulable state, first-line treatment often includes therapies to enhance blood flow and prevent thrombosis such as smoking cessation, antiplatelet therapy, and pentoxifylline. Vasodilating agents, anti-inflammatory agents, anticoagulation, and fibrinolytic therapy also have been used with varying degrees of success.⁷

The Diagnosis: Livedoid Vasculopathy

Livedoid vasculopathy (LV) is a rare cutaneous disorder that most commonly affects the lower legs. It has an estimated incidence of 1 case per 100,000 per year and predominantly affects women.¹ The disease pathogenesis is not fully understood but is thought to involve thrombosis and occlusion of dermal vessels resulting in tissue hypoxia.² Both inherited and acquired thrombophilic conditions frequently are seen in patients with LV.^3,4 Livedoid vasculopathy also has been described as idiopathic⁵ and is associated with immune complex deposition.⁶ However, the number of cases of idiopathic LV may be overestimated; as technological advancements to detect coagulation abnormalities improve, it is hypothesized that this entity will be identified less often.^2,4

Livedoid vasculopathy has been described in the literature using the term PPURPLE (painful purpuric ulcers with reticular pattern of lower extremities).⁷ The triad of livedo racemosa, recurrent painful ulcerations, and residual healing with atrophie blanche characterizes the clinical manifestations of LV; however, all 3 characteristics do not need to appear simultaneously for a diagnosis to be made. The condition has a chronic course with spontaneous remissions and exacerbations. Episodic ulcerations occur, especially in the summertime, and heal slowly, leaving behind atrophic, porcelain white, stellate-shaped scars called atrophie blanche. Livedo racemosa also may be seen in Sneddon syndrome; however, these patients experience neurologic symptoms secondary to cerebrovascular occlusion. In contrast to livedo racemosa, acquired livedo reticularis represents a physiologic hypoperfusion pattern that occurs in response to cold exposure.⁸ A localized sharp pain, known as angina cutis, typically precedes the clinical symptom of painful ulcerations.⁹ Atrophie blanche once was thought to be specific to LV but has been seen in other diseases such as systemic lupus erythematosus and chronic venous insufficiency.²

The diagnosis of LV is based on identification of characteristic clinical features and skin biopsy. In almost all biopsy specimens, histopathology reveals fibrinoid occlusion of vessels in the superficial and mid dermis.⁴ Other findings may include epidermal necrosis and vessel wall hyalinization and infarction² (Figure). Because LV is commonly misdiagnosed as vasculitis, the absence of hallmark features of vasculitis such as neutrophilic infiltrate of blood vessel walls and fibrinoid necrosis suggest the diagnosis. Extensive laboratory evaluation for inherited and acquired coagulation abnormalities should be performed.

Treatment of LV is difficult, as there is currently no consensus on optimal therapy. The mainstay of therapy is to reduce pain, prevent infection, and reduce ulceration and development of atrophie blanche. Underlying causes should be identified and appropriately treated. Because the primary pathogenesis of LV is considered to be a hypercoagulable state, first-line treatment often includes therapies to enhance blood flow and prevent thrombosis such as smoking cessation, antiplatelet therapy, and pentoxifylline. Vasodilating agents, anti-inflammatory agents, anticoagulation, and fibrinolytic therapy also have been used with varying degrees of success.⁷

The Diagnosis: Radiation-Associated Angiosarcoma

At the time of presentation, a 4-mm lesional punch biopsy was obtained (Figure), which revealed an epithelioid neoplasm within the dermis expressing CD31 and CD34, and staining negatively for S-100, CD45, and estrogen and progesterone receptors. The histologic and immunophenotypic findings were compatible with the diagnosis of angiosarcoma. Given the patient’s history of radiation for breast carcinoma several years ago, this tumor was consistent with radiation-associated angiosarcoma (RAAS).

Development of secondary angiosarcoma has been linked to both prior radiation (RAAS) and chronic lymphedema (Stewart-Treves syndrome).¹ Radiation-associated angiosarcoma is defined as a “pathologically confirmed breast or chest wall angiosarcoma arising within a previously irradiated field.”² The incidence of RAAS is estimated to be 0.9 per 1000 individuals following radiation treatment of breast cancer over the subsequent 15 years and a mean time from radiation to development of 7 years.¹ Incidence is expected to increase in the future due to improved likelihood of surviving early-stage breast carcinoma and the increased use of external beam radiation therapy for management of breast cancer.

Differentiating between primary and secondary angiosarcoma of the breast is important. Although primary breast angiosarcoma usually arises in women aged 30 to 40 years, RAAS tends to arise in older women (mean age, 68 years) and is seen only in those women with prior radiation.² Additionally, high-level amplification of MYC, a known photo-oncogene, on chromosome 8 is a key genetic alteration of RAAS that helps to distinguish it from primary angiosarcoma, though this variance may be present in only half of RAAS cases.³ Immunohistochemical analysis of tumor cells for MYC expression correlates well with this amplification and also is helpful in distinguishing atypical vascular lesions from RAAS.⁴ Atypical vascular lesions, similar to RAAS, occur years after radiation exposure and may have a similar clinical presentation. Atypical vascular lesions do not progress to angiosarcoma in reported cases, but clinical and histologic overlap with RAAS make the diagnosis difficult.⁵ In these cases, analysis with fluorescence in situ hybridization or immunohistochemistry for the MYC amplification is important to differentiate these tumors.⁶

At the time of presentation, the majority of patients with RAAS of the breast have localized disease, often with a variable presentation. In all known cases, there have been skin changes present, emphasizing the importance of both patient and clinician vigilance on a regular basis in at-risk individuals. In one study, the most common presentation was breast ecchymosis, which was observed in 55% of patients.⁷ These lesions involve the dermis and are commonly mistaken for benign conditions such as infection or hemorrhage.² In 2 other studies, RAAS most often manifested as a skin nodule or apparent tumor, closely followed by either a rash or bruiselike presentation.^1,2

The overall recommendation for management of patients with ecchymotic skin lesions in previously irradiated regions is to obtain a biopsy specimen for tissue diagnosis. Although there is no standard of care for the management of RAAS, a multidisciplinary approach involving specialists from oncology, surgical oncology, and radiation oncology is recommended. Most often, radical surgery encompassing both the breast parenchyma and the at-risk radiated skin is performed. Extensive surgery has demonstrated the best survival benefits compared to mastectomy alone.⁷ Chemotherapeutics also may be used as adjuncts to surgery, which have been determined to decrease local recurrence rates but have no proven survival benefits.² Adverse prognostic factors for survival are tumor size greater than 10 cm and development of local and/or distant metastases.² Following the diagnosis of RAAS, our patient underwent radical mastectomy with adjuvant chemotherapy and remained disease free 6 months after surgery.

In summary, RAAS is a well-known, albeit relatively uncommon, consequence of radiation therapy. Dermatologists, oncologists, and primary care providers play an important role in recognizing this entity when evaluating patients with ecchymotic lesions as well as nodules or tumors within an irradiated field. Biopsy should be obtained promptly to prevent delay in diagnosis and to expedite referral to appropriate specialists for further evaluation and treatment.

The Diagnosis: Radiation-Associated Angiosarcoma

At the time of presentation, a 4-mm lesional punch biopsy was obtained (Figure), which revealed an epithelioid neoplasm within the dermis expressing CD31 and CD34, and staining negatively for S-100, CD45, and estrogen and progesterone receptors. The histologic and immunophenotypic findings were compatible with the diagnosis of angiosarcoma. Given the patient’s history of radiation for breast carcinoma several years ago, this tumor was consistent with radiation-associated angiosarcoma (RAAS).

Development of secondary angiosarcoma has been linked to both prior radiation (RAAS) and chronic lymphedema (Stewart-Treves syndrome).¹ Radiation-associated angiosarcoma is defined as a “pathologically confirmed breast or chest wall angiosarcoma arising within a previously irradiated field.”² The incidence of RAAS is estimated to be 0.9 per 1000 individuals following radiation treatment of breast cancer over the subsequent 15 years and a mean time from radiation to development of 7 years.¹ Incidence is expected to increase in the future due to improved likelihood of surviving early-stage breast carcinoma and the increased use of external beam radiation therapy for management of breast cancer.

Differentiating between primary and secondary angiosarcoma of the breast is important. Although primary breast angiosarcoma usually arises in women aged 30 to 40 years, RAAS tends to arise in older women (mean age, 68 years) and is seen only in those women with prior radiation.² Additionally, high-level amplification of MYC, a known photo-oncogene, on chromosome 8 is a key genetic alteration of RAAS that helps to distinguish it from primary angiosarcoma, though this variance may be present in only half of RAAS cases.³ Immunohistochemical analysis of tumor cells for MYC expression correlates well with this amplification and also is helpful in distinguishing atypical vascular lesions from RAAS.⁴ Atypical vascular lesions, similar to RAAS, occur years after radiation exposure and may have a similar clinical presentation. Atypical vascular lesions do not progress to angiosarcoma in reported cases, but clinical and histologic overlap with RAAS make the diagnosis difficult.⁵ In these cases, analysis with fluorescence in situ hybridization or immunohistochemistry for the MYC amplification is important to differentiate these tumors.⁶

At the time of presentation, the majority of patients with RAAS of the breast have localized disease, often with a variable presentation. In all known cases, there have been skin changes present, emphasizing the importance of both patient and clinician vigilance on a regular basis in at-risk individuals. In one study, the most common presentation was breast ecchymosis, which was observed in 55% of patients.⁷ These lesions involve the dermis and are commonly mistaken for benign conditions such as infection or hemorrhage.² In 2 other studies, RAAS most often manifested as a skin nodule or apparent tumor, closely followed by either a rash or bruiselike presentation.^1,2

The overall recommendation for management of patients with ecchymotic skin lesions in previously irradiated regions is to obtain a biopsy specimen for tissue diagnosis. Although there is no standard of care for the management of RAAS, a multidisciplinary approach involving specialists from oncology, surgical oncology, and radiation oncology is recommended. Most often, radical surgery encompassing both the breast parenchyma and the at-risk radiated skin is performed. Extensive surgery has demonstrated the best survival benefits compared to mastectomy alone.⁷ Chemotherapeutics also may be used as adjuncts to surgery, which have been determined to decrease local recurrence rates but have no proven survival benefits.² Adverse prognostic factors for survival are tumor size greater than 10 cm and development of local and/or distant metastases.² Following the diagnosis of RAAS, our patient underwent radical mastectomy with adjuvant chemotherapy and remained disease free 6 months after surgery.

In summary, RAAS is a well-known, albeit relatively uncommon, consequence of radiation therapy. Dermatologists, oncologists, and primary care providers play an important role in recognizing this entity when evaluating patients with ecchymotic lesions as well as nodules or tumors within an irradiated field. Biopsy should be obtained promptly to prevent delay in diagnosis and to expedite referral to appropriate specialists for further evaluation and treatment.

The Diagnosis: Radiation-Associated Angiosarcoma

At the time of presentation, a 4-mm lesional punch biopsy was obtained (Figure), which revealed an epithelioid neoplasm within the dermis expressing CD31 and CD34, and staining negatively for S-100, CD45, and estrogen and progesterone receptors. The histologic and immunophenotypic findings were compatible with the diagnosis of angiosarcoma. Given the patient’s history of radiation for breast carcinoma several years ago, this tumor was consistent with radiation-associated angiosarcoma (RAAS).

Development of secondary angiosarcoma has been linked to both prior radiation (RAAS) and chronic lymphedema (Stewart-Treves syndrome).¹ Radiation-associated angiosarcoma is defined as a “pathologically confirmed breast or chest wall angiosarcoma arising within a previously irradiated field.”² The incidence of RAAS is estimated to be 0.9 per 1000 individuals following radiation treatment of breast cancer over the subsequent 15 years and a mean time from radiation to development of 7 years.¹ Incidence is expected to increase in the future due to improved likelihood of surviving early-stage breast carcinoma and the increased use of external beam radiation therapy for management of breast cancer.

Differentiating between primary and secondary angiosarcoma of the breast is important. Although primary breast angiosarcoma usually arises in women aged 30 to 40 years, RAAS tends to arise in older women (mean age, 68 years) and is seen only in those women with prior radiation.² Additionally, high-level amplification of MYC, a known photo-oncogene, on chromosome 8 is a key genetic alteration of RAAS that helps to distinguish it from primary angiosarcoma, though this variance may be present in only half of RAAS cases.³ Immunohistochemical analysis of tumor cells for MYC expression correlates well with this amplification and also is helpful in distinguishing atypical vascular lesions from RAAS.⁴ Atypical vascular lesions, similar to RAAS, occur years after radiation exposure and may have a similar clinical presentation. Atypical vascular lesions do not progress to angiosarcoma in reported cases, but clinical and histologic overlap with RAAS make the diagnosis difficult.⁵ In these cases, analysis with fluorescence in situ hybridization or immunohistochemistry for the MYC amplification is important to differentiate these tumors.⁶

At the time of presentation, the majority of patients with RAAS of the breast have localized disease, often with a variable presentation. In all known cases, there have been skin changes present, emphasizing the importance of both patient and clinician vigilance on a regular basis in at-risk individuals. In one study, the most common presentation was breast ecchymosis, which was observed in 55% of patients.⁷ These lesions involve the dermis and are commonly mistaken for benign conditions such as infection or hemorrhage.² In 2 other studies, RAAS most often manifested as a skin nodule or apparent tumor, closely followed by either a rash or bruiselike presentation.^1,2

The overall recommendation for management of patients with ecchymotic skin lesions in previously irradiated regions is to obtain a biopsy specimen for tissue diagnosis. Although there is no standard of care for the management of RAAS, a multidisciplinary approach involving specialists from oncology, surgical oncology, and radiation oncology is recommended. Most often, radical surgery encompassing both the breast parenchyma and the at-risk radiated skin is performed. Extensive surgery has demonstrated the best survival benefits compared to mastectomy alone.⁷ Chemotherapeutics also may be used as adjuncts to surgery, which have been determined to decrease local recurrence rates but have no proven survival benefits.² Adverse prognostic factors for survival are tumor size greater than 10 cm and development of local and/or distant metastases.² Following the diagnosis of RAAS, our patient underwent radical mastectomy with adjuvant chemotherapy and remained disease free 6 months after surgery.

In summary, RAAS is a well-known, albeit relatively uncommon, consequence of radiation therapy. Dermatologists, oncologists, and primary care providers play an important role in recognizing this entity when evaluating patients with ecchymotic lesions as well as nodules or tumors within an irradiated field. Biopsy should be obtained promptly to prevent delay in diagnosis and to expedite referral to appropriate specialists for further evaluation and treatment.

The Diagnosis: Atypical Mycobacterial Infection

Punch biopsy specimens demonstrated necrotizing granulomatous inflammation in the dermis and subcutis (Figure). Special staining for microorganisms was negative. Tissue culture grew Mycobacterium avium-intracellulare (MAI). The patient began treatment with azithromycin, ethambutol, and rifabutin. Tissue susceptibilities later showed resistance to rifabutin and sensitivity to clarithromycin, moxifloxacin, and clofazimine. She subsequently was switched to azithromycin, clofazimine, and moxifloxacin with good response.

Mycobacterium avium-intracellulare is a slow-growing, nonchromogenic, atypical mycobacteria. Although ubiquitous, it tends to only cause serious infection in the setting of immunosuppression. Transmission usually is through the respiratory or gastrointestinal tract.¹ Skin infections with MAI are uncommon and usually are secondary to seeding from disseminated infection or from direct inoculation.²

The clinical presentations of primary cutaneous MAI are myriad, including an isolated red nodule, multiple ulcers, abscesses, draining sinuses, facial nodules, granulomatous plaques, and panniculitis.^2,3 Of 3 reported cases of primary cutaneous MAI in the form of sporotrichoid lesions, 2 involved patients with AIDS² and 1 involved a cardiac transplant recipient.⁴

Cutaneous MAI is typically diagnosed with skin biopsy and tissue culture. Tissue culture is critical for determining the specific mycobacterial species and antibiotic susceptibilities. Polymerase chain reaction has been utilized to rapidly diagnose cutaneous MAI infection from an acid-fast bacilli–positive tissue sample in which the tissue culture was negative.⁵

Recommended treatment protocols for MAI involve multidrug regimens because of the intrinsic resistance of MAI and the concern for development of resistance with monotherapy.² No definitive guidelines exist for treatment of primary cutaneous MAI infections. However, regimens for the treatment of pulmonary infection that also have been successfully utilized for cutaneous infection include a macrolide, ethambutol, and a rifamycin.⁶ Clinicians should be aware of MAI as a cause of primary cutaneous infections presenting as lymphocutaneous suppurative nodules and ulcerations.

The Diagnosis: Atypical Mycobacterial Infection

Punch biopsy specimens demonstrated necrotizing granulomatous inflammation in the dermis and subcutis (Figure). Special staining for microorganisms was negative. Tissue culture grew Mycobacterium avium-intracellulare (MAI). The patient began treatment with azithromycin, ethambutol, and rifabutin. Tissue susceptibilities later showed resistance to rifabutin and sensitivity to clarithromycin, moxifloxacin, and clofazimine. She subsequently was switched to azithromycin, clofazimine, and moxifloxacin with good response.

Mycobacterium avium-intracellulare is a slow-growing, nonchromogenic, atypical mycobacteria. Although ubiquitous, it tends to only cause serious infection in the setting of immunosuppression. Transmission usually is through the respiratory or gastrointestinal tract.¹ Skin infections with MAI are uncommon and usually are secondary to seeding from disseminated infection or from direct inoculation.²

The clinical presentations of primary cutaneous MAI are myriad, including an isolated red nodule, multiple ulcers, abscesses, draining sinuses, facial nodules, granulomatous plaques, and panniculitis.^2,3 Of 3 reported cases of primary cutaneous MAI in the form of sporotrichoid lesions, 2 involved patients with AIDS² and 1 involved a cardiac transplant recipient.⁴

Cutaneous MAI is typically diagnosed with skin biopsy and tissue culture. Tissue culture is critical for determining the specific mycobacterial species and antibiotic susceptibilities. Polymerase chain reaction has been utilized to rapidly diagnose cutaneous MAI infection from an acid-fast bacilli–positive tissue sample in which the tissue culture was negative.⁵

Recommended treatment protocols for MAI involve multidrug regimens because of the intrinsic resistance of MAI and the concern for development of resistance with monotherapy.² No definitive guidelines exist for treatment of primary cutaneous MAI infections. However, regimens for the treatment of pulmonary infection that also have been successfully utilized for cutaneous infection include a macrolide, ethambutol, and a rifamycin.⁶ Clinicians should be aware of MAI as a cause of primary cutaneous infections presenting as lymphocutaneous suppurative nodules and ulcerations.

The Diagnosis: Atypical Mycobacterial Infection

Punch biopsy specimens demonstrated necrotizing granulomatous inflammation in the dermis and subcutis (Figure). Special staining for microorganisms was negative. Tissue culture grew Mycobacterium avium-intracellulare (MAI). The patient began treatment with azithromycin, ethambutol, and rifabutin. Tissue susceptibilities later showed resistance to rifabutin and sensitivity to clarithromycin, moxifloxacin, and clofazimine. She subsequently was switched to azithromycin, clofazimine, and moxifloxacin with good response.

Mycobacterium avium-intracellulare is a slow-growing, nonchromogenic, atypical mycobacteria. Although ubiquitous, it tends to only cause serious infection in the setting of immunosuppression. Transmission usually is through the respiratory or gastrointestinal tract.¹ Skin infections with MAI are uncommon and usually are secondary to seeding from disseminated infection or from direct inoculation.²

The clinical presentations of primary cutaneous MAI are myriad, including an isolated red nodule, multiple ulcers, abscesses, draining sinuses, facial nodules, granulomatous plaques, and panniculitis.^2,3 Of 3 reported cases of primary cutaneous MAI in the form of sporotrichoid lesions, 2 involved patients with AIDS² and 1 involved a cardiac transplant recipient.⁴

Cutaneous MAI is typically diagnosed with skin biopsy and tissue culture. Tissue culture is critical for determining the specific mycobacterial species and antibiotic susceptibilities. Polymerase chain reaction has been utilized to rapidly diagnose cutaneous MAI infection from an acid-fast bacilli–positive tissue sample in which the tissue culture was negative.⁵

Recommended treatment protocols for MAI involve multidrug regimens because of the intrinsic resistance of MAI and the concern for development of resistance with monotherapy.² No definitive guidelines exist for treatment of primary cutaneous MAI infections. However, regimens for the treatment of pulmonary infection that also have been successfully utilized for cutaneous infection include a macrolide, ethambutol, and a rifamycin.⁶ Clinicians should be aware of MAI as a cause of primary cutaneous infections presenting as lymphocutaneous suppurative nodules and ulcerations.

The Diagnosis: Temporal Triangular Alopecia

Temporal triangular alopecia (TTA), also known as congenital triangular alopecia, was first described in the early 1900s.¹ It presents clinically as a triangular-shaped area of nonscarring alopecia either unilaterally or bilaterally. Limited clinical data suggest that most unilateral cases are on the left frontotemporal region of the scalp. In bilateral cases, there may be asymmetry in size of the area involved.² Dermatoscopically, TTA is characterized by decreased terminal hair follicle density as well as the presence of vellus hairs with an absence of inflammation.³ The majority of TTA is noted between birth and 6 years of life with the areas staying stable thereafter. Large areas of TTA may suggest cerebello-trigeminal-dermal dysplasia (Gomez-Lopez-Hernandez syndrome), a rare neurocutaneous syndrome characterized by rhombencephalosynapsis, trigeminal anesthesia, and parietooccipital alopecia (Online Mendelian Inheritance in Man 601853).⁴ Although TTA is largely idiopathic, it has been suggested that the trait may be paradominant, whereby a postzygotic loss of the wild-type allele in a heterozygotic state causes triangular alopecia and reflects hamartomatous mosaicism.⁵ It also is an important mimicker of alopecia areata. Correct identification prevents unnecessary treatment to the areas of the scalp. Hair restoration surgery has been reported as a tool to treat this disorder.⁶

The Diagnosis: Temporal Triangular Alopecia

Temporal triangular alopecia (TTA), also known as congenital triangular alopecia, was first described in the early 1900s.¹ It presents clinically as a triangular-shaped area of nonscarring alopecia either unilaterally or bilaterally. Limited clinical data suggest that most unilateral cases are on the left frontotemporal region of the scalp. In bilateral cases, there may be asymmetry in size of the area involved.² Dermatoscopically, TTA is characterized by decreased terminal hair follicle density as well as the presence of vellus hairs with an absence of inflammation.³ The majority of TTA is noted between birth and 6 years of life with the areas staying stable thereafter. Large areas of TTA may suggest cerebello-trigeminal-dermal dysplasia (Gomez-Lopez-Hernandez syndrome), a rare neurocutaneous syndrome characterized by rhombencephalosynapsis, trigeminal anesthesia, and parietooccipital alopecia (Online Mendelian Inheritance in Man 601853).⁴ Although TTA is largely idiopathic, it has been suggested that the trait may be paradominant, whereby a postzygotic loss of the wild-type allele in a heterozygotic state causes triangular alopecia and reflects hamartomatous mosaicism.⁵ It also is an important mimicker of alopecia areata. Correct identification prevents unnecessary treatment to the areas of the scalp. Hair restoration surgery has been reported as a tool to treat this disorder.⁶

The Diagnosis: Temporal Triangular Alopecia

Temporal triangular alopecia (TTA), also known as congenital triangular alopecia, was first described in the early 1900s.¹ It presents clinically as a triangular-shaped area of nonscarring alopecia either unilaterally or bilaterally. Limited clinical data suggest that most unilateral cases are on the left frontotemporal region of the scalp. In bilateral cases, there may be asymmetry in size of the area involved.² Dermatoscopically, TTA is characterized by decreased terminal hair follicle density as well as the presence of vellus hairs with an absence of inflammation.³ The majority of TTA is noted between birth and 6 years of life with the areas staying stable thereafter. Large areas of TTA may suggest cerebello-trigeminal-dermal dysplasia (Gomez-Lopez-Hernandez syndrome), a rare neurocutaneous syndrome characterized by rhombencephalosynapsis, trigeminal anesthesia, and parietooccipital alopecia (Online Mendelian Inheritance in Man 601853).⁴ Although TTA is largely idiopathic, it has been suggested that the trait may be paradominant, whereby a postzygotic loss of the wild-type allele in a heterozygotic state causes triangular alopecia and reflects hamartomatous mosaicism.⁵ It also is an important mimicker of alopecia areata. Correct identification prevents unnecessary treatment to the areas of the scalp. Hair restoration surgery has been reported as a tool to treat this disorder.⁶

The Diagnosis: Trigeminal Trophic Syndrome

Trigeminal trophic syndrome (TTS) is a rare condition occurring after injury to the sensory roots of the trigeminal nerve. Trigeminal trophic syndrome was first described in 1933 by Loveman¹ as a complication of ablative treatment of trigeminal neuralgia; however, it has been observed with lesions to the central or peripheral nervous system that damage sensory components of the trigeminal nerve. In our patient, the cause was likely an infarction of the posterior inferior cerebellar artery, which supplies both the cerebellum and the trigeminal nuclei in the brain stem.

Other possible causes of TTS include injury from herpes zoster ophthalmicus; vertebrobasilar insufficiency; trauma; Mycobacterium leprae neuritis; spinal cord degeneration; syringobulbia; or tumors such as astrocytomas, meningiomas, and acoustic neuromas.² The most typical presenting manifestation is a unilateral, crescent-shaped ulceration of the nasal ala, specifically where cartilage is lacking.³ Less frequently, it affects the upper lip, cheeks, forehead, scalp, and ear. It characteristically spares the nasal tip, which derives sensory innervation from the medial branch of the anterior ethmoidal nerve.⁴ The affected dermatomal distribution can show anesthesia or paresthesia, promoting the urge to touch, pick, or rub the area.

Histology of the TTS lesion is nondiagnostic, usually showing a mixed dermal inflammation without evidence of infection, vasculitis, or malignancy. In our patient, Gram stain, Grocott-Gomori methenamine-silver stain, and immunohistochemical stains to rule out leukemia or lymphoma were all negative. In addition, flow cytometry of the forehead tissue also was normal. Tests for human immunodeficiency virus, herpes simplex virus types 1 and 2, hepatitis, syphilis, histoplasmosis, blastomycosis, coccidioides, and tuberculosis were negative.During the biopsy, the patient was noted to have anesthesia of the skin. He also admitted to facial manipulation and was noted to have blood and tissue under the fingernails on mornings when the lesion was left uncovered overnight.

Treatment of TTS often can be difficult, especially if patients do not admit to wound manipulation or if manipulation occurs during sleep. Prevention of further ulceration can sometimes be achieved by occlusive dressing alone with mupirocin. Physical barriers can be supplemented with medications such as amitriptyline, carbamazepine, diazepam, chlorpromazine, and gabapentin to attempt to reduce paresthesia.² Psychiatric consultation can sometimes be necessary and helpful.³ Additionally, negative pressure wound therapy has been used with success in the pediatric setting when digital manipulation is difficult to control.⁵ More aggressive treatments include transcutaneous electrical stimulation, stellate ganglionectomy, radiotherapy, and innervated rotation flaps.^6,7

In summary, recognition of this relatively rare cause of unilateral facial erosions is critical, both to prevent counterproductive treatments such as steroids and to initiate measures to prevent further trauma to the lesion.

The Diagnosis: Trigeminal Trophic Syndrome

Trigeminal trophic syndrome (TTS) is a rare condition occurring after injury to the sensory roots of the trigeminal nerve. Trigeminal trophic syndrome was first described in 1933 by Loveman¹ as a complication of ablative treatment of trigeminal neuralgia; however, it has been observed with lesions to the central or peripheral nervous system that damage sensory components of the trigeminal nerve. In our patient, the cause was likely an infarction of the posterior inferior cerebellar artery, which supplies both the cerebellum and the trigeminal nuclei in the brain stem.

Other possible causes of TTS include injury from herpes zoster ophthalmicus; vertebrobasilar insufficiency; trauma; Mycobacterium leprae neuritis; spinal cord degeneration; syringobulbia; or tumors such as astrocytomas, meningiomas, and acoustic neuromas.² The most typical presenting manifestation is a unilateral, crescent-shaped ulceration of the nasal ala, specifically where cartilage is lacking.³ Less frequently, it affects the upper lip, cheeks, forehead, scalp, and ear. It characteristically spares the nasal tip, which derives sensory innervation from the medial branch of the anterior ethmoidal nerve.⁴ The affected dermatomal distribution can show anesthesia or paresthesia, promoting the urge to touch, pick, or rub the area.

Histology of the TTS lesion is nondiagnostic, usually showing a mixed dermal inflammation without evidence of infection, vasculitis, or malignancy. In our patient, Gram stain, Grocott-Gomori methenamine-silver stain, and immunohistochemical stains to rule out leukemia or lymphoma were all negative. In addition, flow cytometry of the forehead tissue also was normal. Tests for human immunodeficiency virus, herpes simplex virus types 1 and 2, hepatitis, syphilis, histoplasmosis, blastomycosis, coccidioides, and tuberculosis were negative.During the biopsy, the patient was noted to have anesthesia of the skin. He also admitted to facial manipulation and was noted to have blood and tissue under the fingernails on mornings when the lesion was left uncovered overnight.

Treatment of TTS often can be difficult, especially if patients do not admit to wound manipulation or if manipulation occurs during sleep. Prevention of further ulceration can sometimes be achieved by occlusive dressing alone with mupirocin. Physical barriers can be supplemented with medications such as amitriptyline, carbamazepine, diazepam, chlorpromazine, and gabapentin to attempt to reduce paresthesia.² Psychiatric consultation can sometimes be necessary and helpful.³ Additionally, negative pressure wound therapy has been used with success in the pediatric setting when digital manipulation is difficult to control.⁵ More aggressive treatments include transcutaneous electrical stimulation, stellate ganglionectomy, radiotherapy, and innervated rotation flaps.^6,7

In summary, recognition of this relatively rare cause of unilateral facial erosions is critical, both to prevent counterproductive treatments such as steroids and to initiate measures to prevent further trauma to the lesion.

The Diagnosis: Trigeminal Trophic Syndrome

Trigeminal trophic syndrome (TTS) is a rare condition occurring after injury to the sensory roots of the trigeminal nerve. Trigeminal trophic syndrome was first described in 1933 by Loveman¹ as a complication of ablative treatment of trigeminal neuralgia; however, it has been observed with lesions to the central or peripheral nervous system that damage sensory components of the trigeminal nerve. In our patient, the cause was likely an infarction of the posterior inferior cerebellar artery, which supplies both the cerebellum and the trigeminal nuclei in the brain stem.

Other possible causes of TTS include injury from herpes zoster ophthalmicus; vertebrobasilar insufficiency; trauma; Mycobacterium leprae neuritis; spinal cord degeneration; syringobulbia; or tumors such as astrocytomas, meningiomas, and acoustic neuromas.² The most typical presenting manifestation is a unilateral, crescent-shaped ulceration of the nasal ala, specifically where cartilage is lacking.³ Less frequently, it affects the upper lip, cheeks, forehead, scalp, and ear. It characteristically spares the nasal tip, which derives sensory innervation from the medial branch of the anterior ethmoidal nerve.⁴ The affected dermatomal distribution can show anesthesia or paresthesia, promoting the urge to touch, pick, or rub the area.

Histology of the TTS lesion is nondiagnostic, usually showing a mixed dermal inflammation without evidence of infection, vasculitis, or malignancy. In our patient, Gram stain, Grocott-Gomori methenamine-silver stain, and immunohistochemical stains to rule out leukemia or lymphoma were all negative. In addition, flow cytometry of the forehead tissue also was normal. Tests for human immunodeficiency virus, herpes simplex virus types 1 and 2, hepatitis, syphilis, histoplasmosis, blastomycosis, coccidioides, and tuberculosis were negative.During the biopsy, the patient was noted to have anesthesia of the skin. He also admitted to facial manipulation and was noted to have blood and tissue under the fingernails on mornings when the lesion was left uncovered overnight.

Treatment of TTS often can be difficult, especially if patients do not admit to wound manipulation or if manipulation occurs during sleep. Prevention of further ulceration can sometimes be achieved by occlusive dressing alone with mupirocin. Physical barriers can be supplemented with medications such as amitriptyline, carbamazepine, diazepam, chlorpromazine, and gabapentin to attempt to reduce paresthesia.² Psychiatric consultation can sometimes be necessary and helpful.³ Additionally, negative pressure wound therapy has been used with success in the pediatric setting when digital manipulation is difficult to control.⁵ More aggressive treatments include transcutaneous electrical stimulation, stellate ganglionectomy, radiotherapy, and innervated rotation flaps.^6,7

In summary, recognition of this relatively rare cause of unilateral facial erosions is critical, both to prevent counterproductive treatments such as steroids and to initiate measures to prevent further trauma to the lesion.

The Diagnosis: Necrolytic Acral Erythema

Histopathologic analysis of a biopsy specimen from the right leg revealed an erosion with parakeratosis containing neutrophils and marked spongiosis favoring the upper layer of the epidermis with focal individual necrotic keratinocytes. In addition, there was a lymphocytic and neutrophilic exocytosis with edema of the papillary dermal papillae, mild papillary dermal fibrosis, and a mild perivascular lymphocytic infiltrate with neutrophils and occasional eosinophils. Clinicopathologic correlation led to a diagnosis of necrolytic acral erythema (NAE).

The patient was prescribed clobetasol propionate ointment 0.05% and oral zinc sulfate 220 mg twice daily but was initially noncompliant with the topical corticosteroid regimen. He did, however, initiate zinc supplementation, which was later increased to 220 mg 3 times daily. At 3-month follow-up, the lesions had nearly completely cleared (Figure) and the serum zinc level was within reference range at 81 μg/dL.

Necrolytic acral erythema is a rare dermatosis that was first described in 1996 by el Darouti and Abu el Ela¹ in a series of 7 Egyptian patients. Since then, most of the cases have reported concomitant hepatitis C virus (HCV) infection.² Necrolytic acral erythema classically presents with symmetric, well-defined, hyperkeratotic plaques in an acral distribution, typically on the dorsal aspect of the feet.^2,3 Lesions may involve the dorsal aspect of the toes and the lower legs, with less common involvement of the elbows, hands, and buttocks. Patients often report pruritus and/or burning.³

Abdallah et al⁴ proposed several stages of NAE development with erythematous papules with dusky eroded centers progressing to marginated, erythematous to violaceous, lichenified plaques. Over time, these lesions tend to thin with progressive hyperpigmentation.

Histologically, early findings of NAE include acanthosis with epidermal spongiosis and upper dermal perivascular dermatitis. Over time, lesions may exhibit psoriasiform hyperplasia with papillomatosis and parakeratosis, epidermal pallor, subcorneal pustules, vascular ectasia, papillary dermal inflammation, and necrotic keratinocytes. Minimal to moderate acanthosis with an inflammatory infiltrate may be observed later in disease progression.⁵

The differential diagnosis of NAE includes many benign inflammatory skin diseases. Given the acral/extensor distribution of hyperkeratotic lesions and psoriasiform pattern on histopathology, NAE initially may be misdiagnosed as psoriasis. Unlike psoriasis, however, NAE rarely involves palmoplantar skin or nails⁴ and may respond dramatically to treatment with zinc supplementation.^6,7 Necrolytic acral erythema also may be confused with other necrolytic erythemas, including necrolytic migratory erythema, acrodermatitis enteropathica, and pellagra. A deficiency of biotin or essential fatty acids also may mimic NAE. Necrolytic acral erythema can be distinguished from these entities based on its characteristic appearance and distribution, along with comorbid HCV infection.^2-4

Several reports of NAE have revealed an associated zinc deficiency.^2,8 The underlying pathophysiology of zinc deficiency in NAE has not been elucidated but is thought to be related to HCV infection.² Clinical improvement has been reported with zinc supplementation in patients with NAE at dosages of 220 mg twice daily, even in those with initial serum zinc levels within reference range.^6,7 Our patient was observed to have a low serum zinc level that dramatically improved with oral supplementation.

The recognition of this uncommon entity is critical for dermatologists and dermatopathologists, as NAE has been proposed as an early cutaneous marker of HCV and may prompt the initial diagnosis of HCV.^1-10 The severity of NAE has even been linked to HCV severity.^1,8 Treatment of HCV has cleared NAE in several cases,^4,10 implicating the virus in its pathogenesis. A proper workup for liver dysfunction and follow-up with an appropriate health care provider for HCV treatment is crucial. Our patient was encouraged to follow up with the hepatology department, as he had not been evaluated in several years.

The Diagnosis: Necrolytic Acral Erythema

Histopathologic analysis of a biopsy specimen from the right leg revealed an erosion with parakeratosis containing neutrophils and marked spongiosis favoring the upper layer of the epidermis with focal individual necrotic keratinocytes. In addition, there was a lymphocytic and neutrophilic exocytosis with edema of the papillary dermal papillae, mild papillary dermal fibrosis, and a mild perivascular lymphocytic infiltrate with neutrophils and occasional eosinophils. Clinicopathologic correlation led to a diagnosis of necrolytic acral erythema (NAE).

The patient was prescribed clobetasol propionate ointment 0.05% and oral zinc sulfate 220 mg twice daily but was initially noncompliant with the topical corticosteroid regimen. He did, however, initiate zinc supplementation, which was later increased to 220 mg 3 times daily. At 3-month follow-up, the lesions had nearly completely cleared (Figure) and the serum zinc level was within reference range at 81 μg/dL.

Necrolytic acral erythema is a rare dermatosis that was first described in 1996 by el Darouti and Abu el Ela¹ in a series of 7 Egyptian patients. Since then, most of the cases have reported concomitant hepatitis C virus (HCV) infection.² Necrolytic acral erythema classically presents with symmetric, well-defined, hyperkeratotic plaques in an acral distribution, typically on the dorsal aspect of the feet.^2,3 Lesions may involve the dorsal aspect of the toes and the lower legs, with less common involvement of the elbows, hands, and buttocks. Patients often report pruritus and/or burning.³

Abdallah et al⁴ proposed several stages of NAE development with erythematous papules with dusky eroded centers progressing to marginated, erythematous to violaceous, lichenified plaques. Over time, these lesions tend to thin with progressive hyperpigmentation.

Histologically, early findings of NAE include acanthosis with epidermal spongiosis and upper dermal perivascular dermatitis. Over time, lesions may exhibit psoriasiform hyperplasia with papillomatosis and parakeratosis, epidermal pallor, subcorneal pustules, vascular ectasia, papillary dermal inflammation, and necrotic keratinocytes. Minimal to moderate acanthosis with an inflammatory infiltrate may be observed later in disease progression.⁵

The differential diagnosis of NAE includes many benign inflammatory skin diseases. Given the acral/extensor distribution of hyperkeratotic lesions and psoriasiform pattern on histopathology, NAE initially may be misdiagnosed as psoriasis. Unlike psoriasis, however, NAE rarely involves palmoplantar skin or nails⁴ and may respond dramatically to treatment with zinc supplementation.^6,7 Necrolytic acral erythema also may be confused with other necrolytic erythemas, including necrolytic migratory erythema, acrodermatitis enteropathica, and pellagra. A deficiency of biotin or essential fatty acids also may mimic NAE. Necrolytic acral erythema can be distinguished from these entities based on its characteristic appearance and distribution, along with comorbid HCV infection.^2-4

Several reports of NAE have revealed an associated zinc deficiency.^2,8 The underlying pathophysiology of zinc deficiency in NAE has not been elucidated but is thought to be related to HCV infection.² Clinical improvement has been reported with zinc supplementation in patients with NAE at dosages of 220 mg twice daily, even in those with initial serum zinc levels within reference range.^6,7 Our patient was observed to have a low serum zinc level that dramatically improved with oral supplementation.

The recognition of this uncommon entity is critical for dermatologists and dermatopathologists, as NAE has been proposed as an early cutaneous marker of HCV and may prompt the initial diagnosis of HCV.^1-10 The severity of NAE has even been linked to HCV severity.^1,8 Treatment of HCV has cleared NAE in several cases,^4,10 implicating the virus in its pathogenesis. A proper workup for liver dysfunction and follow-up with an appropriate health care provider for HCV treatment is crucial. Our patient was encouraged to follow up with the hepatology department, as he had not been evaluated in several years.

The Diagnosis: Necrolytic Acral Erythema

Histopathologic analysis of a biopsy specimen from the right leg revealed an erosion with parakeratosis containing neutrophils and marked spongiosis favoring the upper layer of the epidermis with focal individual necrotic keratinocytes. In addition, there was a lymphocytic and neutrophilic exocytosis with edema of the papillary dermal papillae, mild papillary dermal fibrosis, and a mild perivascular lymphocytic infiltrate with neutrophils and occasional eosinophils. Clinicopathologic correlation led to a diagnosis of necrolytic acral erythema (NAE).

The patient was prescribed clobetasol propionate ointment 0.05% and oral zinc sulfate 220 mg twice daily but was initially noncompliant with the topical corticosteroid regimen. He did, however, initiate zinc supplementation, which was later increased to 220 mg 3 times daily. At 3-month follow-up, the lesions had nearly completely cleared (Figure) and the serum zinc level was within reference range at 81 μg/dL.

Necrolytic acral erythema is a rare dermatosis that was first described in 1996 by el Darouti and Abu el Ela¹ in a series of 7 Egyptian patients. Since then, most of the cases have reported concomitant hepatitis C virus (HCV) infection.² Necrolytic acral erythema classically presents with symmetric, well-defined, hyperkeratotic plaques in an acral distribution, typically on the dorsal aspect of the feet.^2,3 Lesions may involve the dorsal aspect of the toes and the lower legs, with less common involvement of the elbows, hands, and buttocks. Patients often report pruritus and/or burning.³

Abdallah et al⁴ proposed several stages of NAE development with erythematous papules with dusky eroded centers progressing to marginated, erythematous to violaceous, lichenified plaques. Over time, these lesions tend to thin with progressive hyperpigmentation.

Histologically, early findings of NAE include acanthosis with epidermal spongiosis and upper dermal perivascular dermatitis. Over time, lesions may exhibit psoriasiform hyperplasia with papillomatosis and parakeratosis, epidermal pallor, subcorneal pustules, vascular ectasia, papillary dermal inflammation, and necrotic keratinocytes. Minimal to moderate acanthosis with an inflammatory infiltrate may be observed later in disease progression.⁵

The differential diagnosis of NAE includes many benign inflammatory skin diseases. Given the acral/extensor distribution of hyperkeratotic lesions and psoriasiform pattern on histopathology, NAE initially may be misdiagnosed as psoriasis. Unlike psoriasis, however, NAE rarely involves palmoplantar skin or nails⁴ and may respond dramatically to treatment with zinc supplementation.^6,7 Necrolytic acral erythema also may be confused with other necrolytic erythemas, including necrolytic migratory erythema, acrodermatitis enteropathica, and pellagra. A deficiency of biotin or essential fatty acids also may mimic NAE. Necrolytic acral erythema can be distinguished from these entities based on its characteristic appearance and distribution, along with comorbid HCV infection.^2-4

Several reports of NAE have revealed an associated zinc deficiency.^2,8 The underlying pathophysiology of zinc deficiency in NAE has not been elucidated but is thought to be related to HCV infection.² Clinical improvement has been reported with zinc supplementation in patients with NAE at dosages of 220 mg twice daily, even in those with initial serum zinc levels within reference range.^6,7 Our patient was observed to have a low serum zinc level that dramatically improved with oral supplementation.

The recognition of this uncommon entity is critical for dermatologists and dermatopathologists, as NAE has been proposed as an early cutaneous marker of HCV and may prompt the initial diagnosis of HCV.^1-10 The severity of NAE has even been linked to HCV severity.^1,8 Treatment of HCV has cleared NAE in several cases,^4,10 implicating the virus in its pathogenesis. A proper workup for liver dysfunction and follow-up with an appropriate health care provider for HCV treatment is crucial. Our patient was encouraged to follow up with the hepatology department, as he had not been evaluated in several years.

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹

The Diagnosis: Irritated Seborrheic Keratosis

Biopsies of one of the protruding papules and the underlying plaque were performed. The specimen from the papule showed hyperkeratosis, acanthosis, papillomatosis, and a flattened dermoepidermal junction with demarcated horizontal margin, which demonstrated apparent upward growth of the epidermis. Moderate lymphocytic infiltration in the upper dermis also was observed (Figure, A). The histologic findings of the plaque showed acanthosis, several pseudohorn cysts, hyperpigmentation of the basal layer, and a horizontal demarcation of the dermoepidermal junction (Figure, B).

Seborrheic keratosis is the most common benign epidermal tumor of the skin with variable appearance.¹ It usually begins with well-circumscribed, dull, flat, tan or brown patches that then grow into waxy verrucous papules.¹ There are many clinicopathologic variants of SK such as common SK, stucco keratosis, and dermatosis papulosa nigra in clinical variation, as well as acanthotic, hyperkeratotic, clonal, reticulated, irritated, and melanoacanthoma subtypes based on histological variation.^2,3

Seborrheic keratosis is a tumor of keratinocytic origin. Although genetics, sun exposure,⁴ and human papillomavirus infection⁵ are thought to be causative factors, the precise etiology of SK is unknown.¹

The histology of SK shows monotonous basaloid tumor cells without atypia. It generally is comprised of focal acanthosis and papillomatosis with a sharp flat base. Intraepithelial horn pseudocysts are notable features of SK and increased melanin often is seen.^2,6

Irritated SK is a histologic variant of SK that has been mechanically or chemically irritated or is involved in immunologic responses. Histologically, the dermis underlying an SK lesion filled with a dense lymphocytic infiltration is characteristic.^1,2

For symptomatic or cosmetically undesirable lesions, complete removal of the lesion is the preferred treatment. Cryotherapy, electrodesiccation followed by curettage, curettage followed by desiccation, laser ablation, and surgical excision are effective treatments.¹