Dermatopathology

Cutaneous Larva Migrans 

Cutaneous larva migrans (CLM) is caused by the larval migration of animal hookworms. Ancylostoma braziliense, Ancylostoma ceylanicum, and Ancylostoma caninum are the species most commonly associated with the disease. The hookworm is endemic to tropical and subtropical climates in areas such as Africa, Southeast Asia, South America, and the southeastern United States.¹ Although cats and dogs are most commonly affected, humans can be infected if they are exposed to sand or soil containing hookworm larvae, often due to contamination from animal feces.² Cutaneous larva migrans is characterized by pruritic erythematous papules and linear or serpiginous, reddish brown, elevated tracks most commonly appearing on the feet, buttocks, thighs, and lower legs; however, lesions can appear anywhere. In human hosts, the larvae travel in the epidermis and are unable to invade the dermis; it is speculated that they lack the collagenase enzymes required to penetrate the basement membrane before invading the dermis.² 

On histopathology, there typically are small cavities in the epidermis corresponding to the track of the larvae.³ There often is a spongiotic dermatitis with a mixed inflammatory infiltrate following the larvae with scattered eosinophils. The migrating larvae may be up to 1 mm in size and have bilateral double alae, or winglike projections, on the side of the body (Figure 1).⁴ The larvae are difficult to find on histopathology because they often travel beyond the areas that demonstrate clinical findings. The diagnosis of CLM is mostly clinical, but if a biopsy is performed, the specimen should be taken ahead of the track. 

Disseminated strongyloidiasis is caused by Strongyloides stercoralis. When filariform larvae migrate out of the intestinal tract into the skin, they can cause an urticarial rash and serpiginous patterns on the skin that can move 5 to 15 cm per hour, a clinical condition known as larva currens. In immunocompromised individuals, there can be hyperinfection with diffuse petechial thumbprint purpura seen clinically, which characteristically radiate from the periumbilical area.¹ On pathology, there may be numerous larvae found between the dermal collagen bundles, measuring 9 to 15 µm in diameter. Rarely, they also can be found in small blood vessels.³ They often are accompanied by extravasated red blood cells in the tissues (Figure 2).

Myiasis represents the largest pathogen in the differential diagnosis for CLM. In myiasis, fly larvae will infest human tissue, usually by forming a small cavity in the dermis or subcutaneous tissue. The larvae are visible to the human eye and can be up to several centimeters in length. In the skin, the histology of myiasis usually is accompanied by a heavy mixed inflammatory cell infiltrate with many eosinophils. Fragments of the larvae are seen encased by a thick chitinous cuticle with widely spaced spines or pigmented setae (Figure 3) on the surface of the cuticle.⁵ Layers of striated muscle and internal organs may be seen beneath the cuticle.³

Onchocerciasis, or river blindness, is a parasitic disease caused by Onchocerca volvulus that is most often seen in sub-Saharan Africa. It may cause the skin finding of an onchocercoma, a subcutaneous nodule made up of Onchocerca nematodes. However, when the filaria disseminate, it may cause onchocerciasis with cutaneous findings of an eczematous dermatitis with itching and lichenification.¹ In onchocercal dermatitis, microfilariae may be found in the dermis and there may be a mild dermal chronic inflammatory infiltrate with eosinophils.³ These microfilariae are smaller than Strongyloides larvae (Figure 4).

Sarcoptes scabiei are mites that are pathologically found limited to the stratum corneum. There often is a spongiotic dermatitis as the mite travels with an accompanying mixed cell inflammatory infiltrate with many eosinophils. One or more mites may be seen with or without eggs and excreta or scybala (Figure 5). Pink pigtails may be seen connected to the stratum corneum, representing egg fragments or casings left behind after the mite hatches.³ The female mite measures up to 0.4 mm in length.³

Cutaneous Larva Migrans 

Cutaneous larva migrans (CLM) is caused by the larval migration of animal hookworms. Ancylostoma braziliense, Ancylostoma ceylanicum, and Ancylostoma caninum are the species most commonly associated with the disease. The hookworm is endemic to tropical and subtropical climates in areas such as Africa, Southeast Asia, South America, and the southeastern United States.¹ Although cats and dogs are most commonly affected, humans can be infected if they are exposed to sand or soil containing hookworm larvae, often due to contamination from animal feces.² Cutaneous larva migrans is characterized by pruritic erythematous papules and linear or serpiginous, reddish brown, elevated tracks most commonly appearing on the feet, buttocks, thighs, and lower legs; however, lesions can appear anywhere. In human hosts, the larvae travel in the epidermis and are unable to invade the dermis; it is speculated that they lack the collagenase enzymes required to penetrate the basement membrane before invading the dermis.² 

On histopathology, there typically are small cavities in the epidermis corresponding to the track of the larvae.³ There often is a spongiotic dermatitis with a mixed inflammatory infiltrate following the larvae with scattered eosinophils. The migrating larvae may be up to 1 mm in size and have bilateral double alae, or winglike projections, on the side of the body (Figure 1).⁴ The larvae are difficult to find on histopathology because they often travel beyond the areas that demonstrate clinical findings. The diagnosis of CLM is mostly clinical, but if a biopsy is performed, the specimen should be taken ahead of the track. 

Disseminated strongyloidiasis is caused by Strongyloides stercoralis. When filariform larvae migrate out of the intestinal tract into the skin, they can cause an urticarial rash and serpiginous patterns on the skin that can move 5 to 15 cm per hour, a clinical condition known as larva currens. In immunocompromised individuals, there can be hyperinfection with diffuse petechial thumbprint purpura seen clinically, which characteristically radiate from the periumbilical area.¹ On pathology, there may be numerous larvae found between the dermal collagen bundles, measuring 9 to 15 µm in diameter. Rarely, they also can be found in small blood vessels.³ They often are accompanied by extravasated red blood cells in the tissues (Figure 2).

Myiasis represents the largest pathogen in the differential diagnosis for CLM. In myiasis, fly larvae will infest human tissue, usually by forming a small cavity in the dermis or subcutaneous tissue. The larvae are visible to the human eye and can be up to several centimeters in length. In the skin, the histology of myiasis usually is accompanied by a heavy mixed inflammatory cell infiltrate with many eosinophils. Fragments of the larvae are seen encased by a thick chitinous cuticle with widely spaced spines or pigmented setae (Figure 3) on the surface of the cuticle.⁵ Layers of striated muscle and internal organs may be seen beneath the cuticle.³

Onchocerciasis, or river blindness, is a parasitic disease caused by Onchocerca volvulus that is most often seen in sub-Saharan Africa. It may cause the skin finding of an onchocercoma, a subcutaneous nodule made up of Onchocerca nematodes. However, when the filaria disseminate, it may cause onchocerciasis with cutaneous findings of an eczematous dermatitis with itching and lichenification.¹ In onchocercal dermatitis, microfilariae may be found in the dermis and there may be a mild dermal chronic inflammatory infiltrate with eosinophils.³ These microfilariae are smaller than Strongyloides larvae (Figure 4).

Sarcoptes scabiei are mites that are pathologically found limited to the stratum corneum. There often is a spongiotic dermatitis as the mite travels with an accompanying mixed cell inflammatory infiltrate with many eosinophils. One or more mites may be seen with or without eggs and excreta or scybala (Figure 5). Pink pigtails may be seen connected to the stratum corneum, representing egg fragments or casings left behind after the mite hatches.³ The female mite measures up to 0.4 mm in length.³

Cutaneous Larva Migrans 

Cutaneous larva migrans (CLM) is caused by the larval migration of animal hookworms. Ancylostoma braziliense, Ancylostoma ceylanicum, and Ancylostoma caninum are the species most commonly associated with the disease. The hookworm is endemic to tropical and subtropical climates in areas such as Africa, Southeast Asia, South America, and the southeastern United States.¹ Although cats and dogs are most commonly affected, humans can be infected if they are exposed to sand or soil containing hookworm larvae, often due to contamination from animal feces.² Cutaneous larva migrans is characterized by pruritic erythematous papules and linear or serpiginous, reddish brown, elevated tracks most commonly appearing on the feet, buttocks, thighs, and lower legs; however, lesions can appear anywhere. In human hosts, the larvae travel in the epidermis and are unable to invade the dermis; it is speculated that they lack the collagenase enzymes required to penetrate the basement membrane before invading the dermis.² 

On histopathology, there typically are small cavities in the epidermis corresponding to the track of the larvae.³ There often is a spongiotic dermatitis with a mixed inflammatory infiltrate following the larvae with scattered eosinophils. The migrating larvae may be up to 1 mm in size and have bilateral double alae, or winglike projections, on the side of the body (Figure 1).⁴ The larvae are difficult to find on histopathology because they often travel beyond the areas that demonstrate clinical findings. The diagnosis of CLM is mostly clinical, but if a biopsy is performed, the specimen should be taken ahead of the track. 

Disseminated strongyloidiasis is caused by Strongyloides stercoralis. When filariform larvae migrate out of the intestinal tract into the skin, they can cause an urticarial rash and serpiginous patterns on the skin that can move 5 to 15 cm per hour, a clinical condition known as larva currens. In immunocompromised individuals, there can be hyperinfection with diffuse petechial thumbprint purpura seen clinically, which characteristically radiate from the periumbilical area.¹ On pathology, there may be numerous larvae found between the dermal collagen bundles, measuring 9 to 15 µm in diameter. Rarely, they also can be found in small blood vessels.³ They often are accompanied by extravasated red blood cells in the tissues (Figure 2).

Myiasis represents the largest pathogen in the differential diagnosis for CLM. In myiasis, fly larvae will infest human tissue, usually by forming a small cavity in the dermis or subcutaneous tissue. The larvae are visible to the human eye and can be up to several centimeters in length. In the skin, the histology of myiasis usually is accompanied by a heavy mixed inflammatory cell infiltrate with many eosinophils. Fragments of the larvae are seen encased by a thick chitinous cuticle with widely spaced spines or pigmented setae (Figure 3) on the surface of the cuticle.⁵ Layers of striated muscle and internal organs may be seen beneath the cuticle.³

Onchocerciasis, or river blindness, is a parasitic disease caused by Onchocerca volvulus that is most often seen in sub-Saharan Africa. It may cause the skin finding of an onchocercoma, a subcutaneous nodule made up of Onchocerca nematodes. However, when the filaria disseminate, it may cause onchocerciasis with cutaneous findings of an eczematous dermatitis with itching and lichenification.¹ In onchocercal dermatitis, microfilariae may be found in the dermis and there may be a mild dermal chronic inflammatory infiltrate with eosinophils.³ These microfilariae are smaller than Strongyloides larvae (Figure 4).

Sarcoptes scabiei are mites that are pathologically found limited to the stratum corneum. There often is a spongiotic dermatitis as the mite travels with an accompanying mixed cell inflammatory infiltrate with many eosinophils. One or more mites may be seen with or without eggs and excreta or scybala (Figure 5). Pink pigtails may be seen connected to the stratum corneum, representing egg fragments or casings left behind after the mite hatches.³ The female mite measures up to 0.4 mm in length.³

Case Report

A 50-year-old man with a history of antisynthetase syndrome (positive for anti–Jo-1 polymyositis with interstitial lung disease) and sarcoidosis presented for evaluation of numerous new moles. The lesions had developed on the trunk, arms, legs, hands, and feet approximately 3 weeks after starting azathioprine 100 mg once daily for pulmonary and muscular involvement of antisynthetase syndrome. He denied any preceding cutaneous inflammation or sunburns. He had no personal or family history of skin cancer, and no family members had multiple nevi. Physical examination revealed 30 to 40 benign-appearing, 2- to 5-mm, hyperpigmented macules scattered on the medial aspect of the right foot (Figure 1A), left palm (Figure 1B), back, abdomen, chest, arms, and legs. A larger, somewhat asymmetric, irregularly bordered, and irregularly pigmented macule was noted on the left side of the upper back. A punch biopsy of the lesion revealed a benign, mildly atypical lentiginous compound nevus (Figure 2). Pathology confirmed that the lesions represented eruptive melanocytic nevi (EMN). The patient continued azathioprine therapy and was followed with regular full-body skin examinations. Mycophenolate mofetil was suggested as an alternative therapy, if clinically appropriate, though this change has not been made by the patient’s rheumatologists.

Comment

A PubMed search of articles indexed for MEDLINE using the search terms eruptive melanocytic nevi and azathioprine revealed 14 cases of EMN in the setting of azathioprine therapy, either during azathioprine monotherapy or in combination with other immunosuppressants, including systemic corticosteroids, biologics, and cyclosporine (Table).^1-5 The majority of these cases occurred in renal transplant patients,¹ with 3 additional cases reported in the setting of Crohn disease,^2,3,5 and another in a patient with myasthenia gravis.⁴ Patients ranged in age from 8 to 42 years (mean age, 22 years), with lesions developing a few months to up to 7 years after starting therapy. When specified, the reported lesions typically were small, ranging from 1 to 3 mm in size, and developed rapidly over a couple of months with a predilection for the palms, soles, and trunk. Although dysplastic nevi were described in only 2 patients, melanomas were not detected.

Various hypotheses have sought to explain the largely unknown etiology of EMN. Bovenschen et al³ suggested that immunocompromised patients have diminished immune surveillance in the skin, which allows for unchecked proliferation of melanocytes. Specifically, immune suppression may induce melanocyte-stimulating hormone or melanoma growth stimulatory activity, with composition-specific growth in skin at the palms and soles.^3,4 The preferential growth on the palms and soles suggests that those regions may have special sensitivity to melanocyte-stimulating hormone.⁴ Woodhouse and Maytin⁶ postulated that the increased density of eccrine sweat glands in the palms and soles as well as the absence of pilosebaceous units and apocrine glands and plentiful Pacinian and Meissner corpuscles may allow for a unique response to circulating melanocytic growth factors. Another hypothesis suggests the presence of genetic factors that allow subclinical nests of nevus cells to form, which become clinical eruptions following chemotherapy or immunosuppressive therapy.³ Azathioprine also has been suggested to induce various transcription factors that play a critical role in differentiation and proliferation of melanocytic stem cells, which leads to the formation of nevi.⁴ Our case and others similar to it implore that further studies be done to determine the molecular mechanism driving this phenomenon and whether a specific genetic predisposition exists that lowers the threshold for rapid proliferation of melanocytes given an immunosuppressed status.²

The risk for melanoma development in cases of EMN is unknown. Although our review of the literature did not reveal any melanomas reported in cases attributed to azathioprine, a theoretical risk exists given the established associations between melanoma and immunosuppression as well as increased numbers of nevi.⁶ Accordingly, these patients should be followed with regular skin examinations and biopsies of atypical-appearing lesions as indicated.^2,3,5 Braun et al⁴ also suggested the discontinuance of azathioprine and switch to mycophenolic acid, which has not been noted to cause such eruptions; this drug was recommended in our case.

Case Report

A 50-year-old man with a history of antisynthetase syndrome (positive for anti–Jo-1 polymyositis with interstitial lung disease) and sarcoidosis presented for evaluation of numerous new moles. The lesions had developed on the trunk, arms, legs, hands, and feet approximately 3 weeks after starting azathioprine 100 mg once daily for pulmonary and muscular involvement of antisynthetase syndrome. He denied any preceding cutaneous inflammation or sunburns. He had no personal or family history of skin cancer, and no family members had multiple nevi. Physical examination revealed 30 to 40 benign-appearing, 2- to 5-mm, hyperpigmented macules scattered on the medial aspect of the right foot (Figure 1A), left palm (Figure 1B), back, abdomen, chest, arms, and legs. A larger, somewhat asymmetric, irregularly bordered, and irregularly pigmented macule was noted on the left side of the upper back. A punch biopsy of the lesion revealed a benign, mildly atypical lentiginous compound nevus (Figure 2). Pathology confirmed that the lesions represented eruptive melanocytic nevi (EMN). The patient continued azathioprine therapy and was followed with regular full-body skin examinations. Mycophenolate mofetil was suggested as an alternative therapy, if clinically appropriate, though this change has not been made by the patient’s rheumatologists.

Comment

A PubMed search of articles indexed for MEDLINE using the search terms eruptive melanocytic nevi and azathioprine revealed 14 cases of EMN in the setting of azathioprine therapy, either during azathioprine monotherapy or in combination with other immunosuppressants, including systemic corticosteroids, biologics, and cyclosporine (Table).^1-5 The majority of these cases occurred in renal transplant patients,¹ with 3 additional cases reported in the setting of Crohn disease,^2,3,5 and another in a patient with myasthenia gravis.⁴ Patients ranged in age from 8 to 42 years (mean age, 22 years), with lesions developing a few months to up to 7 years after starting therapy. When specified, the reported lesions typically were small, ranging from 1 to 3 mm in size, and developed rapidly over a couple of months with a predilection for the palms, soles, and trunk. Although dysplastic nevi were described in only 2 patients, melanomas were not detected.

Various hypotheses have sought to explain the largely unknown etiology of EMN. Bovenschen et al³ suggested that immunocompromised patients have diminished immune surveillance in the skin, which allows for unchecked proliferation of melanocytes. Specifically, immune suppression may induce melanocyte-stimulating hormone or melanoma growth stimulatory activity, with composition-specific growth in skin at the palms and soles.^3,4 The preferential growth on the palms and soles suggests that those regions may have special sensitivity to melanocyte-stimulating hormone.⁴ Woodhouse and Maytin⁶ postulated that the increased density of eccrine sweat glands in the palms and soles as well as the absence of pilosebaceous units and apocrine glands and plentiful Pacinian and Meissner corpuscles may allow for a unique response to circulating melanocytic growth factors. Another hypothesis suggests the presence of genetic factors that allow subclinical nests of nevus cells to form, which become clinical eruptions following chemotherapy or immunosuppressive therapy.³ Azathioprine also has been suggested to induce various transcription factors that play a critical role in differentiation and proliferation of melanocytic stem cells, which leads to the formation of nevi.⁴ Our case and others similar to it implore that further studies be done to determine the molecular mechanism driving this phenomenon and whether a specific genetic predisposition exists that lowers the threshold for rapid proliferation of melanocytes given an immunosuppressed status.²

The risk for melanoma development in cases of EMN is unknown. Although our review of the literature did not reveal any melanomas reported in cases attributed to azathioprine, a theoretical risk exists given the established associations between melanoma and immunosuppression as well as increased numbers of nevi.⁶ Accordingly, these patients should be followed with regular skin examinations and biopsies of atypical-appearing lesions as indicated.^2,3,5 Braun et al⁴ also suggested the discontinuance of azathioprine and switch to mycophenolic acid, which has not been noted to cause such eruptions; this drug was recommended in our case.

Case Report

A 50-year-old man with a history of antisynthetase syndrome (positive for anti–Jo-1 polymyositis with interstitial lung disease) and sarcoidosis presented for evaluation of numerous new moles. The lesions had developed on the trunk, arms, legs, hands, and feet approximately 3 weeks after starting azathioprine 100 mg once daily for pulmonary and muscular involvement of antisynthetase syndrome. He denied any preceding cutaneous inflammation or sunburns. He had no personal or family history of skin cancer, and no family members had multiple nevi. Physical examination revealed 30 to 40 benign-appearing, 2- to 5-mm, hyperpigmented macules scattered on the medial aspect of the right foot (Figure 1A), left palm (Figure 1B), back, abdomen, chest, arms, and legs. A larger, somewhat asymmetric, irregularly bordered, and irregularly pigmented macule was noted on the left side of the upper back. A punch biopsy of the lesion revealed a benign, mildly atypical lentiginous compound nevus (Figure 2). Pathology confirmed that the lesions represented eruptive melanocytic nevi (EMN). The patient continued azathioprine therapy and was followed with regular full-body skin examinations. Mycophenolate mofetil was suggested as an alternative therapy, if clinically appropriate, though this change has not been made by the patient’s rheumatologists.

Comment

A PubMed search of articles indexed for MEDLINE using the search terms eruptive melanocytic nevi and azathioprine revealed 14 cases of EMN in the setting of azathioprine therapy, either during azathioprine monotherapy or in combination with other immunosuppressants, including systemic corticosteroids, biologics, and cyclosporine (Table).^1-5 The majority of these cases occurred in renal transplant patients,¹ with 3 additional cases reported in the setting of Crohn disease,^2,3,5 and another in a patient with myasthenia gravis.⁴ Patients ranged in age from 8 to 42 years (mean age, 22 years), with lesions developing a few months to up to 7 years after starting therapy. When specified, the reported lesions typically were small, ranging from 1 to 3 mm in size, and developed rapidly over a couple of months with a predilection for the palms, soles, and trunk. Although dysplastic nevi were described in only 2 patients, melanomas were not detected.

Various hypotheses have sought to explain the largely unknown etiology of EMN. Bovenschen et al³ suggested that immunocompromised patients have diminished immune surveillance in the skin, which allows for unchecked proliferation of melanocytes. Specifically, immune suppression may induce melanocyte-stimulating hormone or melanoma growth stimulatory activity, with composition-specific growth in skin at the palms and soles.^3,4 The preferential growth on the palms and soles suggests that those regions may have special sensitivity to melanocyte-stimulating hormone.⁴ Woodhouse and Maytin⁶ postulated that the increased density of eccrine sweat glands in the palms and soles as well as the absence of pilosebaceous units and apocrine glands and plentiful Pacinian and Meissner corpuscles may allow for a unique response to circulating melanocytic growth factors. Another hypothesis suggests the presence of genetic factors that allow subclinical nests of nevus cells to form, which become clinical eruptions following chemotherapy or immunosuppressive therapy.³ Azathioprine also has been suggested to induce various transcription factors that play a critical role in differentiation and proliferation of melanocytic stem cells, which leads to the formation of nevi.⁴ Our case and others similar to it implore that further studies be done to determine the molecular mechanism driving this phenomenon and whether a specific genetic predisposition exists that lowers the threshold for rapid proliferation of melanocytes given an immunosuppressed status.²

The risk for melanoma development in cases of EMN is unknown. Although our review of the literature did not reveal any melanomas reported in cases attributed to azathioprine, a theoretical risk exists given the established associations between melanoma and immunosuppression as well as increased numbers of nevi.⁶ Accordingly, these patients should be followed with regular skin examinations and biopsies of atypical-appearing lesions as indicated.^2,3,5 Braun et al⁴ also suggested the discontinuance of azathioprine and switch to mycophenolic acid, which has not been noted to cause such eruptions; this drug was recommended in our case.

To the Editor:
Collagenous and elastotic marginal plaques of the hands (CEMPHs) has several names including degenerative collagenous plaques of the hands, keratoelastoidosis marginalis, and digital papular calcific elastosis. This rare disorder is an acquired, slowly progressive, asymptomatic, dermal connective tissue abnormality that is underrecognized and underdiagnosed. Clinical presentation includes hyperkeratotic translucent papules arranged linearly on the radial aspect of the hands.

A 74-year-old woman described having "rough hands" of more than 20 years' duration. She presented with 4-cm wide longitudinal, erythematous, firm, depressed plaques along the lateral edge of the second finger and extending to the medial thumb in both hands (Figure 1). She had attempted multiple treatments by her primary care physician, including topical and oral medications unknown to the patient and light therapy, all without benefit over a period of several years. We have attempted salicylic acid 40%, clobetasol cream 0.05%, and emollient creams containing α-hydroxy acid. At best the condition fluctuated between a subtle raised scale at the edge to smooth and occasionally more red-pink, seemingly unrelated to any treatments.

The patient did not have plaques elsewhere on the body, and notably, the feet were clear. She did not have a history of repeated trauma to the hands and did not engage in manual labor. She denied excessive sun exposure, though she had Fitzpatrick skin type III and a history of multiple precancers and nonmelanoma skin cancers 7 years prior to presentation.

Histology of CEMPH reveals a hyperkeratotic epidermis with an avascular and acellular replacement of the superficial reticular dermis by haphazardly arranged, thickened collagen fibers (Figure 2A-2C). Collagen fibers were oriented perpendicularly to the epidermal surface. Intervening amorphous basophilic elastotic masses were present in the upper dermis with occasional calcification and degenerative elastic fibers (Figure 2D).

Collagenous and elastotic marginal plaques of the hands is a chronic, asymptomatic, sclerotic skin disorder described in a 1960 case series of 5 patients reported by Burks et al.¹ Although it has many names, the most common is CEMPH. Collagenous and elastotic marginal plaques of the hands most often presents in white men aged 50 to 60 years.² Patients typically are asymptomatic with plaques limited to the junction of the palmar and dorsal surfaces of the hands with only minimal intermittent stiffness around the flexor creases. Lesions begin as discrete yellow papules that coalesce to form hyperkeratotic linear plaques with occasional telangiectasia.³

The etiology of CEMPH is attributed to collagen and elastin degeneration by chronic actinic damage, pressure, or trauma.^4,5 The 3 stages of degeneration include an initial linear padded stage, an intermediate padded plaque stage, and an advanced padded hyperkeratotic plaque stage.⁴ Vascular compromise is seen from the enlarged and fused thickened collagen and elastic fibers that in turn lead to ischemic changes, hyperkeratosis with epidermal atrophy, and papillary dermis telangiectasia. Absence or weak expression of keratins 14 and 10 and strong expression of keratin 16 have been reported in the epidermis of CEMPH patients.⁴

Collagenous and elastotic marginal plaques of the hands do not have a specific treatment, as it is a benign, slowly progressive condition. Several treatments such as laser therapy, high-potency topical corticosteroids, topical tazarotene and tretinoin, oral isotretinoin, and cryotherapy have been tried with little long-term success.⁴ Moisturizing may help reduce fissuring, and patients are advised to avoid the sun and repeated trauma to the hands.

The differential diagnosis of CEMPH is summarized in the Table. Two genodermatoses—acrokeratoelastoidosis of Costa and focal acral hyperkeratosis—clinically resemble CEMPH. Acrokeratoelastoidosis of Costa is an autosomal-dominant condition that occurs without trauma in children and young adults. Histopathology shows orthokeratotic hyperkeratosis due to an overproduction of filaggrin in the granular layer of the epidermis. The reticular dermis shows basophilic, thick, curled and fragmented elastic fibers with dilated capillaries that can be seen with Weigert elastic, Verhoeff-van Gieson, or orcein stains. Focal acral hyperkeratosis occurs on the hands and feet, predominantly in black patients. On histology, the epidermis shows a characteristic orthohyperkeratosis, moderate acanthosis, and slight hypergranulosis with no dermal involvment.⁶

Chronic hyperkeratotic eczematous dermatitis is another common entity in the differential characterized by hyperkeratotic plaques that scale and fissure. Biopsy demonstrates a spongiotic acanthotic epidermis.^7,8

Psoriasis of the hands, specifically hyperkeratotic palmoplantar psoriasis, is associated with manual labor, similar to CEMPH. Histology shows epidermal hyperplasia; regular acanthosis; loss of the granular skin layer with prominent dermal capillaries; and a mixed dermal infiltrate of lymphocytes, macrophages, and neutrophils.⁹ Hyperkeratotic palmoplantar lichen planus presents with pruritic papules in the third and fifth decades of life. Histologically, hyperkeratosis, acanthosis, and wedge-shaped hypergranulosis with a lichenoid lymphocytic infiltration at the dermoepidermal junction is seen.¹⁰

Palmoplantar keratodermas due to inflammatory reactive dermatoses include callosities that develop in response to repeated trauma or friction on the skin. On histology, there is prominent hyperkeratosis and acanthosis with moderate papillomatosis.¹¹ Drug-related palmoplantar keratodermas such as those from arsenic exposure can lead to multiple, irregular, verrucous, keratotic, and pigmented lesions on the palms and soles. Histologically, atypical keratinocytes are seen in the epidermis with thick hyperkeratosis and vacuolated cells without solar elastosis.¹²

In conclusion, CEMPH is an underdiagnosed and underrecognized condition characterized by asymptomatic hyperkeratotic linear plaques along the medial aspect of the thumb and radial aspect of the index finger. It is important to keep CEMPH in mind when dealing with occupational cases of repeated long-term trauma or pressure to the hands as well as excessive sun exposure. It also is imperative to separate it from other diseases and avoid misdiagnosing this degenerative collagenous and elastotic disease as a malignant lesion. 

To the Editor:
Collagenous and elastotic marginal plaques of the hands (CEMPHs) has several names including degenerative collagenous plaques of the hands, keratoelastoidosis marginalis, and digital papular calcific elastosis. This rare disorder is an acquired, slowly progressive, asymptomatic, dermal connective tissue abnormality that is underrecognized and underdiagnosed. Clinical presentation includes hyperkeratotic translucent papules arranged linearly on the radial aspect of the hands.

A 74-year-old woman described having "rough hands" of more than 20 years' duration. She presented with 4-cm wide longitudinal, erythematous, firm, depressed plaques along the lateral edge of the second finger and extending to the medial thumb in both hands (Figure 1). She had attempted multiple treatments by her primary care physician, including topical and oral medications unknown to the patient and light therapy, all without benefit over a period of several years. We have attempted salicylic acid 40%, clobetasol cream 0.05%, and emollient creams containing α-hydroxy acid. At best the condition fluctuated between a subtle raised scale at the edge to smooth and occasionally more red-pink, seemingly unrelated to any treatments.

The patient did not have plaques elsewhere on the body, and notably, the feet were clear. She did not have a history of repeated trauma to the hands and did not engage in manual labor. She denied excessive sun exposure, though she had Fitzpatrick skin type III and a history of multiple precancers and nonmelanoma skin cancers 7 years prior to presentation.

Histology of CEMPH reveals a hyperkeratotic epidermis with an avascular and acellular replacement of the superficial reticular dermis by haphazardly arranged, thickened collagen fibers (Figure 2A-2C). Collagen fibers were oriented perpendicularly to the epidermal surface. Intervening amorphous basophilic elastotic masses were present in the upper dermis with occasional calcification and degenerative elastic fibers (Figure 2D).

Collagenous and elastotic marginal plaques of the hands is a chronic, asymptomatic, sclerotic skin disorder described in a 1960 case series of 5 patients reported by Burks et al.¹ Although it has many names, the most common is CEMPH. Collagenous and elastotic marginal plaques of the hands most often presents in white men aged 50 to 60 years.² Patients typically are asymptomatic with plaques limited to the junction of the palmar and dorsal surfaces of the hands with only minimal intermittent stiffness around the flexor creases. Lesions begin as discrete yellow papules that coalesce to form hyperkeratotic linear plaques with occasional telangiectasia.³

The etiology of CEMPH is attributed to collagen and elastin degeneration by chronic actinic damage, pressure, or trauma.^4,5 The 3 stages of degeneration include an initial linear padded stage, an intermediate padded plaque stage, and an advanced padded hyperkeratotic plaque stage.⁴ Vascular compromise is seen from the enlarged and fused thickened collagen and elastic fibers that in turn lead to ischemic changes, hyperkeratosis with epidermal atrophy, and papillary dermis telangiectasia. Absence or weak expression of keratins 14 and 10 and strong expression of keratin 16 have been reported in the epidermis of CEMPH patients.⁴

Collagenous and elastotic marginal plaques of the hands do not have a specific treatment, as it is a benign, slowly progressive condition. Several treatments such as laser therapy, high-potency topical corticosteroids, topical tazarotene and tretinoin, oral isotretinoin, and cryotherapy have been tried with little long-term success.⁴ Moisturizing may help reduce fissuring, and patients are advised to avoid the sun and repeated trauma to the hands.

The differential diagnosis of CEMPH is summarized in the Table. Two genodermatoses—acrokeratoelastoidosis of Costa and focal acral hyperkeratosis—clinically resemble CEMPH. Acrokeratoelastoidosis of Costa is an autosomal-dominant condition that occurs without trauma in children and young adults. Histopathology shows orthokeratotic hyperkeratosis due to an overproduction of filaggrin in the granular layer of the epidermis. The reticular dermis shows basophilic, thick, curled and fragmented elastic fibers with dilated capillaries that can be seen with Weigert elastic, Verhoeff-van Gieson, or orcein stains. Focal acral hyperkeratosis occurs on the hands and feet, predominantly in black patients. On histology, the epidermis shows a characteristic orthohyperkeratosis, moderate acanthosis, and slight hypergranulosis with no dermal involvment.⁶

Chronic hyperkeratotic eczematous dermatitis is another common entity in the differential characterized by hyperkeratotic plaques that scale and fissure. Biopsy demonstrates a spongiotic acanthotic epidermis.^7,8

Psoriasis of the hands, specifically hyperkeratotic palmoplantar psoriasis, is associated with manual labor, similar to CEMPH. Histology shows epidermal hyperplasia; regular acanthosis; loss of the granular skin layer with prominent dermal capillaries; and a mixed dermal infiltrate of lymphocytes, macrophages, and neutrophils.⁹ Hyperkeratotic palmoplantar lichen planus presents with pruritic papules in the third and fifth decades of life. Histologically, hyperkeratosis, acanthosis, and wedge-shaped hypergranulosis with a lichenoid lymphocytic infiltration at the dermoepidermal junction is seen.¹⁰

Palmoplantar keratodermas due to inflammatory reactive dermatoses include callosities that develop in response to repeated trauma or friction on the skin. On histology, there is prominent hyperkeratosis and acanthosis with moderate papillomatosis.¹¹ Drug-related palmoplantar keratodermas such as those from arsenic exposure can lead to multiple, irregular, verrucous, keratotic, and pigmented lesions on the palms and soles. Histologically, atypical keratinocytes are seen in the epidermis with thick hyperkeratosis and vacuolated cells without solar elastosis.¹²

In conclusion, CEMPH is an underdiagnosed and underrecognized condition characterized by asymptomatic hyperkeratotic linear plaques along the medial aspect of the thumb and radial aspect of the index finger. It is important to keep CEMPH in mind when dealing with occupational cases of repeated long-term trauma or pressure to the hands as well as excessive sun exposure. It also is imperative to separate it from other diseases and avoid misdiagnosing this degenerative collagenous and elastotic disease as a malignant lesion. 

To the Editor:
Collagenous and elastotic marginal plaques of the hands (CEMPHs) has several names including degenerative collagenous plaques of the hands, keratoelastoidosis marginalis, and digital papular calcific elastosis. This rare disorder is an acquired, slowly progressive, asymptomatic, dermal connective tissue abnormality that is underrecognized and underdiagnosed. Clinical presentation includes hyperkeratotic translucent papules arranged linearly on the radial aspect of the hands.

A 74-year-old woman described having "rough hands" of more than 20 years' duration. She presented with 4-cm wide longitudinal, erythematous, firm, depressed plaques along the lateral edge of the second finger and extending to the medial thumb in both hands (Figure 1). She had attempted multiple treatments by her primary care physician, including topical and oral medications unknown to the patient and light therapy, all without benefit over a period of several years. We have attempted salicylic acid 40%, clobetasol cream 0.05%, and emollient creams containing α-hydroxy acid. At best the condition fluctuated between a subtle raised scale at the edge to smooth and occasionally more red-pink, seemingly unrelated to any treatments.

The patient did not have plaques elsewhere on the body, and notably, the feet were clear. She did not have a history of repeated trauma to the hands and did not engage in manual labor. She denied excessive sun exposure, though she had Fitzpatrick skin type III and a history of multiple precancers and nonmelanoma skin cancers 7 years prior to presentation.

Histology of CEMPH reveals a hyperkeratotic epidermis with an avascular and acellular replacement of the superficial reticular dermis by haphazardly arranged, thickened collagen fibers (Figure 2A-2C). Collagen fibers were oriented perpendicularly to the epidermal surface. Intervening amorphous basophilic elastotic masses were present in the upper dermis with occasional calcification and degenerative elastic fibers (Figure 2D).

Collagenous and elastotic marginal plaques of the hands is a chronic, asymptomatic, sclerotic skin disorder described in a 1960 case series of 5 patients reported by Burks et al.¹ Although it has many names, the most common is CEMPH. Collagenous and elastotic marginal plaques of the hands most often presents in white men aged 50 to 60 years.² Patients typically are asymptomatic with plaques limited to the junction of the palmar and dorsal surfaces of the hands with only minimal intermittent stiffness around the flexor creases. Lesions begin as discrete yellow papules that coalesce to form hyperkeratotic linear plaques with occasional telangiectasia.³

The etiology of CEMPH is attributed to collagen and elastin degeneration by chronic actinic damage, pressure, or trauma.^4,5 The 3 stages of degeneration include an initial linear padded stage, an intermediate padded plaque stage, and an advanced padded hyperkeratotic plaque stage.⁴ Vascular compromise is seen from the enlarged and fused thickened collagen and elastic fibers that in turn lead to ischemic changes, hyperkeratosis with epidermal atrophy, and papillary dermis telangiectasia. Absence or weak expression of keratins 14 and 10 and strong expression of keratin 16 have been reported in the epidermis of CEMPH patients.⁴

Collagenous and elastotic marginal plaques of the hands do not have a specific treatment, as it is a benign, slowly progressive condition. Several treatments such as laser therapy, high-potency topical corticosteroids, topical tazarotene and tretinoin, oral isotretinoin, and cryotherapy have been tried with little long-term success.⁴ Moisturizing may help reduce fissuring, and patients are advised to avoid the sun and repeated trauma to the hands.

The differential diagnosis of CEMPH is summarized in the Table. Two genodermatoses—acrokeratoelastoidosis of Costa and focal acral hyperkeratosis—clinically resemble CEMPH. Acrokeratoelastoidosis of Costa is an autosomal-dominant condition that occurs without trauma in children and young adults. Histopathology shows orthokeratotic hyperkeratosis due to an overproduction of filaggrin in the granular layer of the epidermis. The reticular dermis shows basophilic, thick, curled and fragmented elastic fibers with dilated capillaries that can be seen with Weigert elastic, Verhoeff-van Gieson, or orcein stains. Focal acral hyperkeratosis occurs on the hands and feet, predominantly in black patients. On histology, the epidermis shows a characteristic orthohyperkeratosis, moderate acanthosis, and slight hypergranulosis with no dermal involvment.⁶

Chronic hyperkeratotic eczematous dermatitis is another common entity in the differential characterized by hyperkeratotic plaques that scale and fissure. Biopsy demonstrates a spongiotic acanthotic epidermis.^7,8

Psoriasis of the hands, specifically hyperkeratotic palmoplantar psoriasis, is associated with manual labor, similar to CEMPH. Histology shows epidermal hyperplasia; regular acanthosis; loss of the granular skin layer with prominent dermal capillaries; and a mixed dermal infiltrate of lymphocytes, macrophages, and neutrophils.⁹ Hyperkeratotic palmoplantar lichen planus presents with pruritic papules in the third and fifth decades of life. Histologically, hyperkeratosis, acanthosis, and wedge-shaped hypergranulosis with a lichenoid lymphocytic infiltration at the dermoepidermal junction is seen.¹⁰

Palmoplantar keratodermas due to inflammatory reactive dermatoses include callosities that develop in response to repeated trauma or friction on the skin. On histology, there is prominent hyperkeratosis and acanthosis with moderate papillomatosis.¹¹ Drug-related palmoplantar keratodermas such as those from arsenic exposure can lead to multiple, irregular, verrucous, keratotic, and pigmented lesions on the palms and soles. Histologically, atypical keratinocytes are seen in the epidermis with thick hyperkeratosis and vacuolated cells without solar elastosis.¹²

In conclusion, CEMPH is an underdiagnosed and underrecognized condition characterized by asymptomatic hyperkeratotic linear plaques along the medial aspect of the thumb and radial aspect of the index finger. It is important to keep CEMPH in mind when dealing with occupational cases of repeated long-term trauma or pressure to the hands as well as excessive sun exposure. It also is imperative to separate it from other diseases and avoid misdiagnosing this degenerative collagenous and elastotic disease as a malignant lesion. 

The Diagnosis: Erythema Dyschromicum Perstans

Erythema dyschromicum perstans (EDP), also referred to as ashy dermatosis, was first described by Ramirez¹ in 1957 who labeled the patients los cenicientos (the ashen ones). It preferentially affects women in the second decade of life; however, patients of all ages can be affected, with reported cases occurring in children as young as 2 years of age.² Most patients have Fitzpatrick skin type IV, mainly Amerindian, Hispanic South Asian, and Southwest Asian; however, there are cases reported worldwide.³ A genetic predisposition is proposed, as major histocompatibility complex genes associated with HLA-DR4⁎0407 are frequent in Mexican patients with ashy dermatosis and in the Amerindian population.⁴

The etiology of EDP is unknown. Various contributing factors have been reported including alimentary, occupational, and climatic factors,^5,6 yet none have been conclusively demonstrated. High expression of CD36 (thrombospondin receptor not found in normal skin) in spinous and granular layers, CD94 (cytotoxic cell marker) in the basal cell layer and in the inflammatory dermal infiltrate,⁷ and focal keratinocytic expression of intercellular adhesion molecule I (CD54) in the active lesions of EDP, as well as the absence of these findings in normal skin, suggests an immunologic role in the development of the disease.⁸

Erythema dyschromicum perstans presents clinically with blue-gray hyperpigmented macules varying in size and shape and developing symmetrically in both sun-exposed and sun-protected areas of the face, neck, trunk, arms, and sometimes the dorsal hands (Figures 1 and 2). Notable sparing of the palms, soles, scalp, and mucous membranes occurs.

Occasionally, in the early active stage of the disease, elevated erythematous borders are noted surrounding the hyperpigmented macules. Eventually a hypopigmented halo develops after a prolonged duration of disease.⁹ The eruption typically is chronic and asymptomatic, though some cases may be pruritic.¹⁰

Histopathologically, the early lesions of EDP with an erythematous active border reveal lichenoid dermatitis with basal vacuolar change and occasional Civatte bodies. A mild to moderate perivascular lymphohistiocytic infiltrate admixed with melanophages can be seen in the papillary dermis (Figure 3). In older lesions, the inflammatory infiltrate is sparse, and pigment incontinence consistent with postinflammatory pigmentation is prominent, though melanophages extending deep into the reticular dermis may aid in distinguishing EDP from other causes of postinflammatory pigment alteration.^7,11

Erythema dyschromicum perstans and lichen planus pigmentosus (LPP) may be indistinguishable histopathologically and may both be variants of lichen planus actinicus. Lichen planus pigmentosus often differs from EDP in that it presents with brown-black macules and patches often on the face and flexural areas. A subset of cases of LPP also may have mucous membrane involvement. The erythematous border that characterizes the active lesion of EDP is characteristically absent in LPP. In addition, pruritus often is reported with LPP. Direct immunofluorescence is not a beneficial tool in distinguishing the entities.¹²

Other differential diagnoses of predominantly facial hyperpigmentation include a lichenoid drug eruption; drug-induced hyperpigmentation (deposition disorder); postinflammatory hyperpigmentation following atopic dermatitis; contact dermatitis or photosensitivity reaction; early pinta; and cutaneous findings of systemic diseases manifesting with diffuse hyperpigmentation such as lupus erythematosus, dermatomyositis, hemochromatosis, and Addison disease. A detailed history including medication use, thorough clinical examination, and careful histopathologic evaluation will help distinguish these conditions.

Chrysiasis is a rare bluish to slate gray discoloration of the skin that predominantly occurs in sun-exposed areas. It is caused by chronic use of gold salts, which have been used to treat rheumatoid arthritis. UV light may contribute to induce the uptake of gold and subsequently stimulate tyrosinase activity.¹³ Histologic features of chrysiasis include dermal and perivascular gold deposition within the macrophages and endothelial cells as well as extracellular granules. It demonstrates an orange-red birefringence on fluorescent microscopy.^14,15

Minocycline-induced hyperpigmentation is a well-recognized side effect of this drug. It is dose dependent and appears as a blue-black pigmentation that most frequently affects the shins, ankles, and arms.¹⁶ Three distinct types were documented: abnormal discoloration of the skin that has been linked to deposition of pigmented metabolites of minocycline producing blue-black pigmentation at the site of scarring or prior inflammation (type 1); blue-gray pigmentation affecting normal skin, mainly the legs (type 2); and elevated levels of melanin on the sun-exposed areas producing dirty skin syndrome (type 3).^17,18

Topical and systemic corticosteroids, UV light therapy, oral dapsone, griseofulvin, retinoids, and clofazimine are reported as treatment options for ashy dermatosis, though results typically are disappointing.⁷

The Diagnosis: Erythema Dyschromicum Perstans

Erythema dyschromicum perstans (EDP), also referred to as ashy dermatosis, was first described by Ramirez¹ in 1957 who labeled the patients los cenicientos (the ashen ones). It preferentially affects women in the second decade of life; however, patients of all ages can be affected, with reported cases occurring in children as young as 2 years of age.² Most patients have Fitzpatrick skin type IV, mainly Amerindian, Hispanic South Asian, and Southwest Asian; however, there are cases reported worldwide.³ A genetic predisposition is proposed, as major histocompatibility complex genes associated with HLA-DR4⁎0407 are frequent in Mexican patients with ashy dermatosis and in the Amerindian population.⁴

The etiology of EDP is unknown. Various contributing factors have been reported including alimentary, occupational, and climatic factors,^5,6 yet none have been conclusively demonstrated. High expression of CD36 (thrombospondin receptor not found in normal skin) in spinous and granular layers, CD94 (cytotoxic cell marker) in the basal cell layer and in the inflammatory dermal infiltrate,⁷ and focal keratinocytic expression of intercellular adhesion molecule I (CD54) in the active lesions of EDP, as well as the absence of these findings in normal skin, suggests an immunologic role in the development of the disease.⁸

Erythema dyschromicum perstans presents clinically with blue-gray hyperpigmented macules varying in size and shape and developing symmetrically in both sun-exposed and sun-protected areas of the face, neck, trunk, arms, and sometimes the dorsal hands (Figures 1 and 2). Notable sparing of the palms, soles, scalp, and mucous membranes occurs.

Occasionally, in the early active stage of the disease, elevated erythematous borders are noted surrounding the hyperpigmented macules. Eventually a hypopigmented halo develops after a prolonged duration of disease.⁹ The eruption typically is chronic and asymptomatic, though some cases may be pruritic.¹⁰

Histopathologically, the early lesions of EDP with an erythematous active border reveal lichenoid dermatitis with basal vacuolar change and occasional Civatte bodies. A mild to moderate perivascular lymphohistiocytic infiltrate admixed with melanophages can be seen in the papillary dermis (Figure 3). In older lesions, the inflammatory infiltrate is sparse, and pigment incontinence consistent with postinflammatory pigmentation is prominent, though melanophages extending deep into the reticular dermis may aid in distinguishing EDP from other causes of postinflammatory pigment alteration.^7,11

Erythema dyschromicum perstans and lichen planus pigmentosus (LPP) may be indistinguishable histopathologically and may both be variants of lichen planus actinicus. Lichen planus pigmentosus often differs from EDP in that it presents with brown-black macules and patches often on the face and flexural areas. A subset of cases of LPP also may have mucous membrane involvement. The erythematous border that characterizes the active lesion of EDP is characteristically absent in LPP. In addition, pruritus often is reported with LPP. Direct immunofluorescence is not a beneficial tool in distinguishing the entities.¹²

Other differential diagnoses of predominantly facial hyperpigmentation include a lichenoid drug eruption; drug-induced hyperpigmentation (deposition disorder); postinflammatory hyperpigmentation following atopic dermatitis; contact dermatitis or photosensitivity reaction; early pinta; and cutaneous findings of systemic diseases manifesting with diffuse hyperpigmentation such as lupus erythematosus, dermatomyositis, hemochromatosis, and Addison disease. A detailed history including medication use, thorough clinical examination, and careful histopathologic evaluation will help distinguish these conditions.

Chrysiasis is a rare bluish to slate gray discoloration of the skin that predominantly occurs in sun-exposed areas. It is caused by chronic use of gold salts, which have been used to treat rheumatoid arthritis. UV light may contribute to induce the uptake of gold and subsequently stimulate tyrosinase activity.¹³ Histologic features of chrysiasis include dermal and perivascular gold deposition within the macrophages and endothelial cells as well as extracellular granules. It demonstrates an orange-red birefringence on fluorescent microscopy.^14,15

Minocycline-induced hyperpigmentation is a well-recognized side effect of this drug. It is dose dependent and appears as a blue-black pigmentation that most frequently affects the shins, ankles, and arms.¹⁶ Three distinct types were documented: abnormal discoloration of the skin that has been linked to deposition of pigmented metabolites of minocycline producing blue-black pigmentation at the site of scarring or prior inflammation (type 1); blue-gray pigmentation affecting normal skin, mainly the legs (type 2); and elevated levels of melanin on the sun-exposed areas producing dirty skin syndrome (type 3).^17,18

Topical and systemic corticosteroids, UV light therapy, oral dapsone, griseofulvin, retinoids, and clofazimine are reported as treatment options for ashy dermatosis, though results typically are disappointing.⁷

The Diagnosis: Erythema Dyschromicum Perstans

Erythema dyschromicum perstans (EDP), also referred to as ashy dermatosis, was first described by Ramirez¹ in 1957 who labeled the patients los cenicientos (the ashen ones). It preferentially affects women in the second decade of life; however, patients of all ages can be affected, with reported cases occurring in children as young as 2 years of age.² Most patients have Fitzpatrick skin type IV, mainly Amerindian, Hispanic South Asian, and Southwest Asian; however, there are cases reported worldwide.³ A genetic predisposition is proposed, as major histocompatibility complex genes associated with HLA-DR4⁎0407 are frequent in Mexican patients with ashy dermatosis and in the Amerindian population.⁴

The etiology of EDP is unknown. Various contributing factors have been reported including alimentary, occupational, and climatic factors,^5,6 yet none have been conclusively demonstrated. High expression of CD36 (thrombospondin receptor not found in normal skin) in spinous and granular layers, CD94 (cytotoxic cell marker) in the basal cell layer and in the inflammatory dermal infiltrate,⁷ and focal keratinocytic expression of intercellular adhesion molecule I (CD54) in the active lesions of EDP, as well as the absence of these findings in normal skin, suggests an immunologic role in the development of the disease.⁸

Erythema dyschromicum perstans presents clinically with blue-gray hyperpigmented macules varying in size and shape and developing symmetrically in both sun-exposed and sun-protected areas of the face, neck, trunk, arms, and sometimes the dorsal hands (Figures 1 and 2). Notable sparing of the palms, soles, scalp, and mucous membranes occurs.

Occasionally, in the early active stage of the disease, elevated erythematous borders are noted surrounding the hyperpigmented macules. Eventually a hypopigmented halo develops after a prolonged duration of disease.⁹ The eruption typically is chronic and asymptomatic, though some cases may be pruritic.¹⁰

Histopathologically, the early lesions of EDP with an erythematous active border reveal lichenoid dermatitis with basal vacuolar change and occasional Civatte bodies. A mild to moderate perivascular lymphohistiocytic infiltrate admixed with melanophages can be seen in the papillary dermis (Figure 3). In older lesions, the inflammatory infiltrate is sparse, and pigment incontinence consistent with postinflammatory pigmentation is prominent, though melanophages extending deep into the reticular dermis may aid in distinguishing EDP from other causes of postinflammatory pigment alteration.^7,11

Erythema dyschromicum perstans and lichen planus pigmentosus (LPP) may be indistinguishable histopathologically and may both be variants of lichen planus actinicus. Lichen planus pigmentosus often differs from EDP in that it presents with brown-black macules and patches often on the face and flexural areas. A subset of cases of LPP also may have mucous membrane involvement. The erythematous border that characterizes the active lesion of EDP is characteristically absent in LPP. In addition, pruritus often is reported with LPP. Direct immunofluorescence is not a beneficial tool in distinguishing the entities.¹²

Other differential diagnoses of predominantly facial hyperpigmentation include a lichenoid drug eruption; drug-induced hyperpigmentation (deposition disorder); postinflammatory hyperpigmentation following atopic dermatitis; contact dermatitis or photosensitivity reaction; early pinta; and cutaneous findings of systemic diseases manifesting with diffuse hyperpigmentation such as lupus erythematosus, dermatomyositis, hemochromatosis, and Addison disease. A detailed history including medication use, thorough clinical examination, and careful histopathologic evaluation will help distinguish these conditions.

Chrysiasis is a rare bluish to slate gray discoloration of the skin that predominantly occurs in sun-exposed areas. It is caused by chronic use of gold salts, which have been used to treat rheumatoid arthritis. UV light may contribute to induce the uptake of gold and subsequently stimulate tyrosinase activity.¹³ Histologic features of chrysiasis include dermal and perivascular gold deposition within the macrophages and endothelial cells as well as extracellular granules. It demonstrates an orange-red birefringence on fluorescent microscopy.^14,15

Minocycline-induced hyperpigmentation is a well-recognized side effect of this drug. It is dose dependent and appears as a blue-black pigmentation that most frequently affects the shins, ankles, and arms.¹⁶ Three distinct types were documented: abnormal discoloration of the skin that has been linked to deposition of pigmented metabolites of minocycline producing blue-black pigmentation at the site of scarring or prior inflammation (type 1); blue-gray pigmentation affecting normal skin, mainly the legs (type 2); and elevated levels of melanin on the sun-exposed areas producing dirty skin syndrome (type 3).^17,18

Topical and systemic corticosteroids, UV light therapy, oral dapsone, griseofulvin, retinoids, and clofazimine are reported as treatment options for ashy dermatosis, though results typically are disappointing.⁷

To the Editor:

A 57-year-old man with a history of type 2 diabetes mellitus and hypertension was hospitalized for heart disease resulting in an aortic valve replacement and multiple-vessel bypass grafting. He experienced a stormy septic postoperative course during which he developed numerous palpable purplish plaques (Figure 1). The lesions were bilateral and more heavily involved the lower legs and buttocks. The head and neck remained free of skin lesions. Additionally, the patient reported a bilateral burning sensation from the knees to the feet.

Punch biopsies of lesions from the right upper arm were obtained. Hematoxylin and eosin staining revealed neutrophilic-predominant small vessel vasculitis (Figure 2A) with the upper dermal location more heavily involved, as demonstrated by involvement of a superficial vascular plexus (Figures 2B and 2C) that was consistent with Henoch-Schönlein purpura (HSP). The diagnosis later was confirmed with immunofluorescence. Direct immunofluorescence revealed granular IgA deposition around the superficial vascular plexus (Figure 3). No IgG, IgM, C3, C5b-9 complement complex, or fibrinogen deposition was seen. Additionally, periodic acid-Schiff staining failed to show microorganisms, thrombi, or intravascular hyaline material.

At our initial consultation, we observed an ill-appearing afebrile man with purplish plaques. Our impression was that he had vasculitis and not warfarin necrosis, which had been suspected by the cardiovascular team. The burning sensation noted by the patient lent credence to our vasculitic diagnosis. Proteinuria and hematuria were present; however, the values for blood urea nitrogen, creatinine, and glomerular filtration rate all remained within reference range. His signs and symptoms responded dramatically to prednisone. He remains on 1 mg of prednisone daily and a nephrologist continues to monitor renal function as an outpatient.

Henoch-Schönlein purpura is a systemic leukocytoclastic vasculitis involving small vessels. The small vessel vasculitis is associated with IgA antigen-antibody complex deposition in areas throughout the body. Palpable purpura typically is seen on the skin, which characteristically involves dependent areas such as the legs and the buttocks. Lesions normally are present bilaterally in a symmetric distribution. Initially, the lesions develop as erythematous macules that progress to purple, nonblanching, palpable, and purpuric plaques.¹ Henoch-Schönlein purpura most commonly involves the skin; however, other locations for the immune complexes include the gastrointestinal tract, joints, and kidneys.² The cause for the body's immunogenic deposition response is unknown in a majority of cases.

Henoch-Schönlein purpura most commonly is seen in the pediatric population with a predilection for males.³ The incidence in the pediatric population is 13.5 to 20 per 100,000 children per year; HSP is more rare in adults.^4-6 Henoch-Schönlein purpura most often is a self-limiting disease that requires only supportive treatment. The signs and symptoms last 4 to 6 weeks in most patients and resolve completely in 94% of children and 89% of adults.⁷ Renal involvement carries a worse prognosis. Adult patients have a higher incidence of renal involvement, renal insufficiency, and subsequent progression to end-stage renal disease.^3,8-10 In a study by Hung et al⁸ of 65 children and 22 adult HSP patients, 12 adults presented with renal involvement in which hematuria or proteinuria were present. Of them, 6 progressed to renal insufficiency (defined as having a plasma creatinine concentration>1.2 mg/dL).⁸ Fogazzi et al¹¹ reported similar findings; 8 of 16 patients affected with HSP progressed to renal insufficiency with creatinine clearances ranging from 31 to 60 mL/min, and 3 patients required chronic dialysis. Pillebout et al⁹ evaluated 250 adults with HSP and 32% reached renal insufficiency with creatinine clearances of less than 50 mL/min, with 11% of patients developing end-stage renal disease. The degree of hematuria and/or proteinuria has been shown to be an effective prognostic indicator.^9,10 Coppo et al¹⁰ found a similar prognosis among children and adults with HSP-related nephritis.

Our patient described the burning sensation as occurring bilaterally from the knees down to the feet, which provided an additional clue that small vessel vasculitis was involved, as occluded blood vessels can cause ischemia to nerves and perivascular involvement can affect nearby neural structures. Sais et al¹² demonstrated that paresthesia in the setting of HSP was a risk factor for systemic involvement. Of note,  our patient's paresthesia lasted only several days.

The cause of HSP is not always as evident in the adult population as in the pediatric population. Early diagnosis of HSP in adults may allow for the proper instatement of treatment to deter long-term renal complications. Follow-up with urinalysis is recommended because a small percentage of patients have a late progression to renal failure.^13,14

Because the dermatologists involved in this case knew where and what types of biopsies to perform, a correct diagnosis was obtained quickly, allowing for the correct therapeutic intervention. After the diagnosis of HSP is made in an adult, nephrology should be consulted early in the treatment course.

To the Editor:

A 57-year-old man with a history of type 2 diabetes mellitus and hypertension was hospitalized for heart disease resulting in an aortic valve replacement and multiple-vessel bypass grafting. He experienced a stormy septic postoperative course during which he developed numerous palpable purplish plaques (Figure 1). The lesions were bilateral and more heavily involved the lower legs and buttocks. The head and neck remained free of skin lesions. Additionally, the patient reported a bilateral burning sensation from the knees to the feet.

Punch biopsies of lesions from the right upper arm were obtained. Hematoxylin and eosin staining revealed neutrophilic-predominant small vessel vasculitis (Figure 2A) with the upper dermal location more heavily involved, as demonstrated by involvement of a superficial vascular plexus (Figures 2B and 2C) that was consistent with Henoch-Schönlein purpura (HSP). The diagnosis later was confirmed with immunofluorescence. Direct immunofluorescence revealed granular IgA deposition around the superficial vascular plexus (Figure 3). No IgG, IgM, C3, C5b-9 complement complex, or fibrinogen deposition was seen. Additionally, periodic acid-Schiff staining failed to show microorganisms, thrombi, or intravascular hyaline material.

At our initial consultation, we observed an ill-appearing afebrile man with purplish plaques. Our impression was that he had vasculitis and not warfarin necrosis, which had been suspected by the cardiovascular team. The burning sensation noted by the patient lent credence to our vasculitic diagnosis. Proteinuria and hematuria were present; however, the values for blood urea nitrogen, creatinine, and glomerular filtration rate all remained within reference range. His signs and symptoms responded dramatically to prednisone. He remains on 1 mg of prednisone daily and a nephrologist continues to monitor renal function as an outpatient.

Henoch-Schönlein purpura is a systemic leukocytoclastic vasculitis involving small vessels. The small vessel vasculitis is associated with IgA antigen-antibody complex deposition in areas throughout the body. Palpable purpura typically is seen on the skin, which characteristically involves dependent areas such as the legs and the buttocks. Lesions normally are present bilaterally in a symmetric distribution. Initially, the lesions develop as erythematous macules that progress to purple, nonblanching, palpable, and purpuric plaques.¹ Henoch-Schönlein purpura most commonly involves the skin; however, other locations for the immune complexes include the gastrointestinal tract, joints, and kidneys.² The cause for the body's immunogenic deposition response is unknown in a majority of cases.

Henoch-Schönlein purpura most commonly is seen in the pediatric population with a predilection for males.³ The incidence in the pediatric population is 13.5 to 20 per 100,000 children per year; HSP is more rare in adults.^4-6 Henoch-Schönlein purpura most often is a self-limiting disease that requires only supportive treatment. The signs and symptoms last 4 to 6 weeks in most patients and resolve completely in 94% of children and 89% of adults.⁷ Renal involvement carries a worse prognosis. Adult patients have a higher incidence of renal involvement, renal insufficiency, and subsequent progression to end-stage renal disease.^3,8-10 In a study by Hung et al⁸ of 65 children and 22 adult HSP patients, 12 adults presented with renal involvement in which hematuria or proteinuria were present. Of them, 6 progressed to renal insufficiency (defined as having a plasma creatinine concentration>1.2 mg/dL).⁸ Fogazzi et al¹¹ reported similar findings; 8 of 16 patients affected with HSP progressed to renal insufficiency with creatinine clearances ranging from 31 to 60 mL/min, and 3 patients required chronic dialysis. Pillebout et al⁹ evaluated 250 adults with HSP and 32% reached renal insufficiency with creatinine clearances of less than 50 mL/min, with 11% of patients developing end-stage renal disease. The degree of hematuria and/or proteinuria has been shown to be an effective prognostic indicator.^9,10 Coppo et al¹⁰ found a similar prognosis among children and adults with HSP-related nephritis.

Our patient described the burning sensation as occurring bilaterally from the knees down to the feet, which provided an additional clue that small vessel vasculitis was involved, as occluded blood vessels can cause ischemia to nerves and perivascular involvement can affect nearby neural structures. Sais et al¹² demonstrated that paresthesia in the setting of HSP was a risk factor for systemic involvement. Of note,  our patient's paresthesia lasted only several days.

The cause of HSP is not always as evident in the adult population as in the pediatric population. Early diagnosis of HSP in adults may allow for the proper instatement of treatment to deter long-term renal complications. Follow-up with urinalysis is recommended because a small percentage of patients have a late progression to renal failure.^13,14

Because the dermatologists involved in this case knew where and what types of biopsies to perform, a correct diagnosis was obtained quickly, allowing for the correct therapeutic intervention. After the diagnosis of HSP is made in an adult, nephrology should be consulted early in the treatment course.

To the Editor:

A 57-year-old man with a history of type 2 diabetes mellitus and hypertension was hospitalized for heart disease resulting in an aortic valve replacement and multiple-vessel bypass grafting. He experienced a stormy septic postoperative course during which he developed numerous palpable purplish plaques (Figure 1). The lesions were bilateral and more heavily involved the lower legs and buttocks. The head and neck remained free of skin lesions. Additionally, the patient reported a bilateral burning sensation from the knees to the feet.

Punch biopsies of lesions from the right upper arm were obtained. Hematoxylin and eosin staining revealed neutrophilic-predominant small vessel vasculitis (Figure 2A) with the upper dermal location more heavily involved, as demonstrated by involvement of a superficial vascular plexus (Figures 2B and 2C) that was consistent with Henoch-Schönlein purpura (HSP). The diagnosis later was confirmed with immunofluorescence. Direct immunofluorescence revealed granular IgA deposition around the superficial vascular plexus (Figure 3). No IgG, IgM, C3, C5b-9 complement complex, or fibrinogen deposition was seen. Additionally, periodic acid-Schiff staining failed to show microorganisms, thrombi, or intravascular hyaline material.

At our initial consultation, we observed an ill-appearing afebrile man with purplish plaques. Our impression was that he had vasculitis and not warfarin necrosis, which had been suspected by the cardiovascular team. The burning sensation noted by the patient lent credence to our vasculitic diagnosis. Proteinuria and hematuria were present; however, the values for blood urea nitrogen, creatinine, and glomerular filtration rate all remained within reference range. His signs and symptoms responded dramatically to prednisone. He remains on 1 mg of prednisone daily and a nephrologist continues to monitor renal function as an outpatient.

Henoch-Schönlein purpura is a systemic leukocytoclastic vasculitis involving small vessels. The small vessel vasculitis is associated with IgA antigen-antibody complex deposition in areas throughout the body. Palpable purpura typically is seen on the skin, which characteristically involves dependent areas such as the legs and the buttocks. Lesions normally are present bilaterally in a symmetric distribution. Initially, the lesions develop as erythematous macules that progress to purple, nonblanching, palpable, and purpuric plaques.¹ Henoch-Schönlein purpura most commonly involves the skin; however, other locations for the immune complexes include the gastrointestinal tract, joints, and kidneys.² The cause for the body's immunogenic deposition response is unknown in a majority of cases.

Henoch-Schönlein purpura most commonly is seen in the pediatric population with a predilection for males.³ The incidence in the pediatric population is 13.5 to 20 per 100,000 children per year; HSP is more rare in adults.^4-6 Henoch-Schönlein purpura most often is a self-limiting disease that requires only supportive treatment. The signs and symptoms last 4 to 6 weeks in most patients and resolve completely in 94% of children and 89% of adults.⁷ Renal involvement carries a worse prognosis. Adult patients have a higher incidence of renal involvement, renal insufficiency, and subsequent progression to end-stage renal disease.^3,8-10 In a study by Hung et al⁸ of 65 children and 22 adult HSP patients, 12 adults presented with renal involvement in which hematuria or proteinuria were present. Of them, 6 progressed to renal insufficiency (defined as having a plasma creatinine concentration>1.2 mg/dL).⁸ Fogazzi et al¹¹ reported similar findings; 8 of 16 patients affected with HSP progressed to renal insufficiency with creatinine clearances ranging from 31 to 60 mL/min, and 3 patients required chronic dialysis. Pillebout et al⁹ evaluated 250 adults with HSP and 32% reached renal insufficiency with creatinine clearances of less than 50 mL/min, with 11% of patients developing end-stage renal disease. The degree of hematuria and/or proteinuria has been shown to be an effective prognostic indicator.^9,10 Coppo et al¹⁰ found a similar prognosis among children and adults with HSP-related nephritis.

Our patient described the burning sensation as occurring bilaterally from the knees down to the feet, which provided an additional clue that small vessel vasculitis was involved, as occluded blood vessels can cause ischemia to nerves and perivascular involvement can affect nearby neural structures. Sais et al¹² demonstrated that paresthesia in the setting of HSP was a risk factor for systemic involvement. Of note,  our patient's paresthesia lasted only several days.

The cause of HSP is not always as evident in the adult population as in the pediatric population. Early diagnosis of HSP in adults may allow for the proper instatement of treatment to deter long-term renal complications. Follow-up with urinalysis is recommended because a small percentage of patients have a late progression to renal failure.^13,14

Because the dermatologists involved in this case knew where and what types of biopsies to perform, a correct diagnosis was obtained quickly, allowing for the correct therapeutic intervention. After the diagnosis of HSP is made in an adult, nephrology should be consulted early in the treatment course.

The Diagnosis: Hypertrophic Lupus Erythematosus

Physical examination at initial presentation revealed well-demarcated, 2- to 3-cm plaques with scale distributed most extensively on the elbows and shins with lesser involvement of the chest and abdomen. After treatment with topical steroids, adalimumab, methotrexate, and narrowband UVB phototherapy, new annular, erythematous, and edematous lesions began to appear on the chest and abdomen (Figure 1). These new lesions appeared less hyperkeratotic than the older ones.

Biopsy of a hyperkeratotic lesion from the patient's arm revealed marked hyperkeratosis, parakeratosis, epidermal hyperplasia, focal vacuolar change, solar elastosis, and transepidermal elastotic elimination (Figure 2A). A second biopsy performed on a newer chest lesion revealed interface changes, degeneration of the basal layer, follicular plugging, and dermal mucin (Figure 2B). Serology revealed an antinuclear antibody (ANA) titer of 1:1280 (reference range, <1:40 dilution) and hemoglobin of 11.5 g/dL (reference range, 14.0-17.5 g/dL). On the basis of clinical, histologic, and serologic findings, hypertrophic lupus erythematosus (LE) was diagnosed. The patient was treated with oral prednisone, which resulted in rapid improvement.

Hypertrophic LE is a rare subset of chronic cutaneous lupus first described by Behcet¹ in 1942. Lesions are identified as verrucous keratotic plaques with a characteristic erythematous indurated border.² Patients predominantly are middle-aged women with lesions distributed on sun-exposed areas. Most often, hypertrophic LE is seen in association with the classic lesions of discoid LE; however, patients may present exclusively with the cutaneous manifestations of hypertrophic LE. More rarely, as seen in this case, hypertrophic LE may present in conjunction with systemic features.³ The diagnosis of systemic LE requires 4 of the following criteria be fulfilled: malar rash; discoid rash; photosensitivity; oral ulcers; arthritis; cardiopulmonary serositis; renal involvement; positive ANA titer; and neurologic, hematologic, or immunologic disorders.⁴ Our patient qualified for discoid rash, photosensitivity, cardiopulmonary involvement with mitral valve defects and pulmonary pleuritis, hematologic disorder (anemia), and a positive ANA titer. Furthermore, in patients with only cutaneous discoid LE, serology generally reveals negative or low-titer ANA and negative anti-Ro antibodies.⁵

Hypertrophic LE is characterized histologically by irregular epidermal hyperplasia in association with features of classic cutaneous LE. Distinctive features of cutaneous LE include interface changes, follicular plugging, dermal mucin, and angiocentric lymphocytic inflammation.⁶ Notably, additional biopsies of the less hyperkeratotic lesions on our patient's chest and abdomen were performed, which revealed classic cutaneous LE features (Figure 2B).

Hypertrophic LE has 2 histological variants: lichen planus-like and keratoacanthoma (KA)-like patterns. Most cases are described as lichen planus-like, with a dense bandlike infiltrate in association with irregular epidermal hyperplasia, vacuolar interface changes, and reactive squamous atypia.⁵ In contrast, the less common KA-like lesions consist of a keratinous center with vigorous squamous epithelial proliferation.⁶

Clinically, hypertrophic LE may resemble hypertrophic psoriasis, lichen planus, KA, or squamous cell carcinoma (SCC). Due to the presence of pseudocarcinomatous hyperplasia, the histopathologic differential includes hypertrophic lichen planus, SCC, KA, and deep fungal infections. However, these other diseases lack the classic features of cutaneous LE, which include interface changes, follicular plugging, dermal mucin, and perivascular lymphocytic inflammation. Additionally, transepidermal elastotic elimination (Figure 2A) helps distinguish hypertrophic LE from other diagnoses.⁷ One of the most important tasks is distinguishing hypertrophic LE from SCC. Hypertrophic LE does not typically display eosinophil infiltrates, which differentiates it from SCC and KA. Additionally, studies report that CD123 positivity can be useful.⁶ Positive plasmacytoid dendritic cells are abundant at the dermoepidermal junction in hypertrophic LE, while only single or rare clusters of CD123⁺ cells are seen in SCC.⁸ Also, SCC has been found to arise in long-standing cutaneous LE lesions including both discoid and hypertrophic LE. Therefore, clinical and sometimes histological follow-up is required.

Hypertrophic LE often is challenging to treat and frequently is resistant to antimalarial drugs. The primary goals of treatment involve reducing inflammatory infiltrate and minimizing hyperkeratinization. Topical corticosteroids and calcineurin inhibitors often are inadequate as monotherapy due to reduced penetrance through the thick lesions; however, intralesional corticosteroids may be beneficial in patients with localized disease.⁹ Unfortunately, topical or intralesional treatments are impractical in patients with extensive lesions, as seen in our patient, in which case systemic corticosteroids can be beneficial.

Topical retinoids also have been found to be highly effective.¹⁰ Specifically, retinoids such as acitretin and isotretinoin, in some cases combined with antimalarial drugs, are effective in reducing the keratinization of these lesions. Successful treatment also has been reported with ustekinumab, thalidomide, mycophenolate mofetil, and pulsed dye laser.¹¹ As in other types of cutaneous LE, hyperkeratotic LE is photosensitive; avoidance of prolonged sun exposure should be advised.⁸

The Diagnosis: Hypertrophic Lupus Erythematosus

Physical examination at initial presentation revealed well-demarcated, 2- to 3-cm plaques with scale distributed most extensively on the elbows and shins with lesser involvement of the chest and abdomen. After treatment with topical steroids, adalimumab, methotrexate, and narrowband UVB phototherapy, new annular, erythematous, and edematous lesions began to appear on the chest and abdomen (Figure 1). These new lesions appeared less hyperkeratotic than the older ones.

Biopsy of a hyperkeratotic lesion from the patient's arm revealed marked hyperkeratosis, parakeratosis, epidermal hyperplasia, focal vacuolar change, solar elastosis, and transepidermal elastotic elimination (Figure 2A). A second biopsy performed on a newer chest lesion revealed interface changes, degeneration of the basal layer, follicular plugging, and dermal mucin (Figure 2B). Serology revealed an antinuclear antibody (ANA) titer of 1:1280 (reference range, <1:40 dilution) and hemoglobin of 11.5 g/dL (reference range, 14.0-17.5 g/dL). On the basis of clinical, histologic, and serologic findings, hypertrophic lupus erythematosus (LE) was diagnosed. The patient was treated with oral prednisone, which resulted in rapid improvement.

Hypertrophic LE is a rare subset of chronic cutaneous lupus first described by Behcet¹ in 1942. Lesions are identified as verrucous keratotic plaques with a characteristic erythematous indurated border.² Patients predominantly are middle-aged women with lesions distributed on sun-exposed areas. Most often, hypertrophic LE is seen in association with the classic lesions of discoid LE; however, patients may present exclusively with the cutaneous manifestations of hypertrophic LE. More rarely, as seen in this case, hypertrophic LE may present in conjunction with systemic features.³ The diagnosis of systemic LE requires 4 of the following criteria be fulfilled: malar rash; discoid rash; photosensitivity; oral ulcers; arthritis; cardiopulmonary serositis; renal involvement; positive ANA titer; and neurologic, hematologic, or immunologic disorders.⁴ Our patient qualified for discoid rash, photosensitivity, cardiopulmonary involvement with mitral valve defects and pulmonary pleuritis, hematologic disorder (anemia), and a positive ANA titer. Furthermore, in patients with only cutaneous discoid LE, serology generally reveals negative or low-titer ANA and negative anti-Ro antibodies.⁵

Hypertrophic LE is characterized histologically by irregular epidermal hyperplasia in association with features of classic cutaneous LE. Distinctive features of cutaneous LE include interface changes, follicular plugging, dermal mucin, and angiocentric lymphocytic inflammation.⁶ Notably, additional biopsies of the less hyperkeratotic lesions on our patient's chest and abdomen were performed, which revealed classic cutaneous LE features (Figure 2B).

Hypertrophic LE has 2 histological variants: lichen planus-like and keratoacanthoma (KA)-like patterns. Most cases are described as lichen planus-like, with a dense bandlike infiltrate in association with irregular epidermal hyperplasia, vacuolar interface changes, and reactive squamous atypia.⁵ In contrast, the less common KA-like lesions consist of a keratinous center with vigorous squamous epithelial proliferation.⁶

Clinically, hypertrophic LE may resemble hypertrophic psoriasis, lichen planus, KA, or squamous cell carcinoma (SCC). Due to the presence of pseudocarcinomatous hyperplasia, the histopathologic differential includes hypertrophic lichen planus, SCC, KA, and deep fungal infections. However, these other diseases lack the classic features of cutaneous LE, which include interface changes, follicular plugging, dermal mucin, and perivascular lymphocytic inflammation. Additionally, transepidermal elastotic elimination (Figure 2A) helps distinguish hypertrophic LE from other diagnoses.⁷ One of the most important tasks is distinguishing hypertrophic LE from SCC. Hypertrophic LE does not typically display eosinophil infiltrates, which differentiates it from SCC and KA. Additionally, studies report that CD123 positivity can be useful.⁶ Positive plasmacytoid dendritic cells are abundant at the dermoepidermal junction in hypertrophic LE, while only single or rare clusters of CD123⁺ cells are seen in SCC.⁸ Also, SCC has been found to arise in long-standing cutaneous LE lesions including both discoid and hypertrophic LE. Therefore, clinical and sometimes histological follow-up is required.

Hypertrophic LE often is challenging to treat and frequently is resistant to antimalarial drugs. The primary goals of treatment involve reducing inflammatory infiltrate and minimizing hyperkeratinization. Topical corticosteroids and calcineurin inhibitors often are inadequate as monotherapy due to reduced penetrance through the thick lesions; however, intralesional corticosteroids may be beneficial in patients with localized disease.⁹ Unfortunately, topical or intralesional treatments are impractical in patients with extensive lesions, as seen in our patient, in which case systemic corticosteroids can be beneficial.

Topical retinoids also have been found to be highly effective.¹⁰ Specifically, retinoids such as acitretin and isotretinoin, in some cases combined with antimalarial drugs, are effective in reducing the keratinization of these lesions. Successful treatment also has been reported with ustekinumab, thalidomide, mycophenolate mofetil, and pulsed dye laser.¹¹ As in other types of cutaneous LE, hyperkeratotic LE is photosensitive; avoidance of prolonged sun exposure should be advised.⁸

The Diagnosis: Hypertrophic Lupus Erythematosus

Physical examination at initial presentation revealed well-demarcated, 2- to 3-cm plaques with scale distributed most extensively on the elbows and shins with lesser involvement of the chest and abdomen. After treatment with topical steroids, adalimumab, methotrexate, and narrowband UVB phototherapy, new annular, erythematous, and edematous lesions began to appear on the chest and abdomen (Figure 1). These new lesions appeared less hyperkeratotic than the older ones.

Biopsy of a hyperkeratotic lesion from the patient's arm revealed marked hyperkeratosis, parakeratosis, epidermal hyperplasia, focal vacuolar change, solar elastosis, and transepidermal elastotic elimination (Figure 2A). A second biopsy performed on a newer chest lesion revealed interface changes, degeneration of the basal layer, follicular plugging, and dermal mucin (Figure 2B). Serology revealed an antinuclear antibody (ANA) titer of 1:1280 (reference range, <1:40 dilution) and hemoglobin of 11.5 g/dL (reference range, 14.0-17.5 g/dL). On the basis of clinical, histologic, and serologic findings, hypertrophic lupus erythematosus (LE) was diagnosed. The patient was treated with oral prednisone, which resulted in rapid improvement.

Hypertrophic LE is a rare subset of chronic cutaneous lupus first described by Behcet¹ in 1942. Lesions are identified as verrucous keratotic plaques with a characteristic erythematous indurated border.² Patients predominantly are middle-aged women with lesions distributed on sun-exposed areas. Most often, hypertrophic LE is seen in association with the classic lesions of discoid LE; however, patients may present exclusively with the cutaneous manifestations of hypertrophic LE. More rarely, as seen in this case, hypertrophic LE may present in conjunction with systemic features.³ The diagnosis of systemic LE requires 4 of the following criteria be fulfilled: malar rash; discoid rash; photosensitivity; oral ulcers; arthritis; cardiopulmonary serositis; renal involvement; positive ANA titer; and neurologic, hematologic, or immunologic disorders.⁴ Our patient qualified for discoid rash, photosensitivity, cardiopulmonary involvement with mitral valve defects and pulmonary pleuritis, hematologic disorder (anemia), and a positive ANA titer. Furthermore, in patients with only cutaneous discoid LE, serology generally reveals negative or low-titer ANA and negative anti-Ro antibodies.⁵

Hypertrophic LE is characterized histologically by irregular epidermal hyperplasia in association with features of classic cutaneous LE. Distinctive features of cutaneous LE include interface changes, follicular plugging, dermal mucin, and angiocentric lymphocytic inflammation.⁶ Notably, additional biopsies of the less hyperkeratotic lesions on our patient's chest and abdomen were performed, which revealed classic cutaneous LE features (Figure 2B).

Hypertrophic LE has 2 histological variants: lichen planus-like and keratoacanthoma (KA)-like patterns. Most cases are described as lichen planus-like, with a dense bandlike infiltrate in association with irregular epidermal hyperplasia, vacuolar interface changes, and reactive squamous atypia.⁵ In contrast, the less common KA-like lesions consist of a keratinous center with vigorous squamous epithelial proliferation.⁶

Clinically, hypertrophic LE may resemble hypertrophic psoriasis, lichen planus, KA, or squamous cell carcinoma (SCC). Due to the presence of pseudocarcinomatous hyperplasia, the histopathologic differential includes hypertrophic lichen planus, SCC, KA, and deep fungal infections. However, these other diseases lack the classic features of cutaneous LE, which include interface changes, follicular plugging, dermal mucin, and perivascular lymphocytic inflammation. Additionally, transepidermal elastotic elimination (Figure 2A) helps distinguish hypertrophic LE from other diagnoses.⁷ One of the most important tasks is distinguishing hypertrophic LE from SCC. Hypertrophic LE does not typically display eosinophil infiltrates, which differentiates it from SCC and KA. Additionally, studies report that CD123 positivity can be useful.⁶ Positive plasmacytoid dendritic cells are abundant at the dermoepidermal junction in hypertrophic LE, while only single or rare clusters of CD123⁺ cells are seen in SCC.⁸ Also, SCC has been found to arise in long-standing cutaneous LE lesions including both discoid and hypertrophic LE. Therefore, clinical and sometimes histological follow-up is required.

Hypertrophic LE often is challenging to treat and frequently is resistant to antimalarial drugs. The primary goals of treatment involve reducing inflammatory infiltrate and minimizing hyperkeratinization. Topical corticosteroids and calcineurin inhibitors often are inadequate as monotherapy due to reduced penetrance through the thick lesions; however, intralesional corticosteroids may be beneficial in patients with localized disease.⁹ Unfortunately, topical or intralesional treatments are impractical in patients with extensive lesions, as seen in our patient, in which case systemic corticosteroids can be beneficial.

Topical retinoids also have been found to be highly effective.¹⁰ Specifically, retinoids such as acitretin and isotretinoin, in some cases combined with antimalarial drugs, are effective in reducing the keratinization of these lesions. Successful treatment also has been reported with ustekinumab, thalidomide, mycophenolate mofetil, and pulsed dye laser.¹¹ As in other types of cutaneous LE, hyperkeratotic LE is photosensitive; avoidance of prolonged sun exposure should be advised.⁸

The Diagnosis: Verrucous Hemangioma

Verrucous hemangioma (VH) is a rare vascular anomaly that has not been definitively delineated as a malformation or a tumor, as it has features of both. Verrucous hemangioma presents at birth as a compressible soft mass with a red violaceous hue favoring the legs.^1,2 Over time VH will develop a warty, friable, and keratotic surface that can begin to evolve as early as 6 months or as late as 34 years of age.³ Verrucous hemangioma does not involute and tends to grow proportionally with the patient. Thus, VH classically has been considered a vascular malformation.

On histopathology VH shows collections of uniform, thin-walled vessels with a multilamellated basement membrane throughout the dermis, similar to an infantile hemangioma (IH). These lesions extend deep into the subcutaneous tissue and often involve the underlying fascia. The papillary dermis has large ectatic vessels, while the epidermis displays verrucous hyperkeratosis, papillomatosis, and irregular acanthosis without viral change (Figure).^4,5 The superficial component can resemble an angiokeratoma; however, VH is differentiated by a deeper component that is often larger in size and has a more protracted clinical course.

Similar to IH, immunohistochemical studies have shown that VH expresses Wilms tumor 1 and glucose transporter 1 but is negative for D2-40.⁴ These findings suggest that VH is a vascular tumor rather than a vascular malformation, as was previously reported.⁶ Additional research has shown that the immunohistochemical staining profile of VH is nearly identical to IH, which has led to postulation that VH may be of placental mesodermal origin, as has been hypothesized for IH.⁵

Due to its deep infiltration and tendency for recurrence, VH is most effectively treated with wide local excision.^3,6-8 Preoperative planning with magnetic resonance imaging may be indicated. Although laser monotherapy and other local destructive therapies have been largely unsuccessful, postsurgical laser therapy with CO2 lasers as well as dual pulsed dye laser and Nd:YAG laser have shown promise in preventing recurrence.³

The Diagnosis: Verrucous Hemangioma

Verrucous hemangioma (VH) is a rare vascular anomaly that has not been definitively delineated as a malformation or a tumor, as it has features of both. Verrucous hemangioma presents at birth as a compressible soft mass with a red violaceous hue favoring the legs.^1,2 Over time VH will develop a warty, friable, and keratotic surface that can begin to evolve as early as 6 months or as late as 34 years of age.³ Verrucous hemangioma does not involute and tends to grow proportionally with the patient. Thus, VH classically has been considered a vascular malformation.

On histopathology VH shows collections of uniform, thin-walled vessels with a multilamellated basement membrane throughout the dermis, similar to an infantile hemangioma (IH). These lesions extend deep into the subcutaneous tissue and often involve the underlying fascia. The papillary dermis has large ectatic vessels, while the epidermis displays verrucous hyperkeratosis, papillomatosis, and irregular acanthosis without viral change (Figure).^4,5 The superficial component can resemble an angiokeratoma; however, VH is differentiated by a deeper component that is often larger in size and has a more protracted clinical course.

Similar to IH, immunohistochemical studies have shown that VH expresses Wilms tumor 1 and glucose transporter 1 but is negative for D2-40.⁴ These findings suggest that VH is a vascular tumor rather than a vascular malformation, as was previously reported.⁶ Additional research has shown that the immunohistochemical staining profile of VH is nearly identical to IH, which has led to postulation that VH may be of placental mesodermal origin, as has been hypothesized for IH.⁵

Due to its deep infiltration and tendency for recurrence, VH is most effectively treated with wide local excision.^3,6-8 Preoperative planning with magnetic resonance imaging may be indicated. Although laser monotherapy and other local destructive therapies have been largely unsuccessful, postsurgical laser therapy with CO2 lasers as well as dual pulsed dye laser and Nd:YAG laser have shown promise in preventing recurrence.³

The Diagnosis: Verrucous Hemangioma

Verrucous hemangioma (VH) is a rare vascular anomaly that has not been definitively delineated as a malformation or a tumor, as it has features of both. Verrucous hemangioma presents at birth as a compressible soft mass with a red violaceous hue favoring the legs.^1,2 Over time VH will develop a warty, friable, and keratotic surface that can begin to evolve as early as 6 months or as late as 34 years of age.³ Verrucous hemangioma does not involute and tends to grow proportionally with the patient. Thus, VH classically has been considered a vascular malformation.

On histopathology VH shows collections of uniform, thin-walled vessels with a multilamellated basement membrane throughout the dermis, similar to an infantile hemangioma (IH). These lesions extend deep into the subcutaneous tissue and often involve the underlying fascia. The papillary dermis has large ectatic vessels, while the epidermis displays verrucous hyperkeratosis, papillomatosis, and irregular acanthosis without viral change (Figure).^4,5 The superficial component can resemble an angiokeratoma; however, VH is differentiated by a deeper component that is often larger in size and has a more protracted clinical course.

Similar to IH, immunohistochemical studies have shown that VH expresses Wilms tumor 1 and glucose transporter 1 but is negative for D2-40.⁴ These findings suggest that VH is a vascular tumor rather than a vascular malformation, as was previously reported.⁶ Additional research has shown that the immunohistochemical staining profile of VH is nearly identical to IH, which has led to postulation that VH may be of placental mesodermal origin, as has been hypothesized for IH.⁵

Due to its deep infiltration and tendency for recurrence, VH is most effectively treated with wide local excision.^3,6-8 Preoperative planning with magnetic resonance imaging may be indicated. Although laser monotherapy and other local destructive therapies have been largely unsuccessful, postsurgical laser therapy with CO2 lasers as well as dual pulsed dye laser and Nd:YAG laser have shown promise in preventing recurrence.³

Primary Cutaneous B-cell Lymphoma

Cutaneous B-cell lymphomas (CBCLs) are a diverse but rare group of cutaneous lympho­proliferative neoplasms that make up approximately 20% of the total number of hematolymphoid neoplasms primary to the skin.¹ These lymphomas are comprised of neoplastic B cells in various stages of differentiation. As a whole, they are rare neoplasms that primarily involve the head, neck, trunk, arms, or legs.¹ Clinically, patients present with nontender, compressible, solitary, red to violaceous papules or nodules. Most CBCLs are considered low-grade malignancies with nonaggressive behavior and excellent prognosis; however, the diffuse large B-cell lymphomas, including but not limited to intravascular and leg type; lymphomatoid granulomatosis; and B-cell lymphoblastic lymphoma can act more aggressively.¹

Histopathologic examination of primary CBCL generally reveals a relatively normal epidermis accompanied by a nodular to diffuse monomorphic lymphocytic cellular infiltrate in the dermis that can occasionally extend into the subcutaneous tissue (quiz image). Although not specific for CBCLs, oftentimes there is an acellular portion of the superficial papillary dermis known as a grenz zone that can serve as a histopathologic clue to the diagnosis of a cutaneous lymphoproliferative disorder. The list of malignant B-cell neoplasms is extensive (eg, cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center lymphoma, diffuse large B-cell lymphoma, intravascular large B-cell lymphoma), and few are seen in the skin.

The most common type of CBCL is marginal zone B-cell lymphoma, which is considered to be a tumor of mucosa-associated (or skin-associated) lymphoid tissue. It is characterized by a monomorphous population of small mature lymphocytes showing characteristics of the B cells of the marginal zone of the lymph node. Some cells have the features of centrocytes/centroblasts (Figure 1) demonstrated by slightly irregular or indented nuclei and generous amounts of cytoplasm. Larger and more pleomorphic cells such as immunoblasts are similarly noted (Figure 1). The quiz image and Figure 1 demonstrate a cutaneous marginal zone B-cell lymphoma. A histomorphologic clue supporting a diagnosis of marginal zone B-cell lymphoma over reactive lymphoid hyperplasia is a B-cell predominate (B- to T-cell ratio of at least 3 to 1) infiltrate that is comprised of marginal zone-type cells. Immunohistochemistry demonstrating fewer differentiated B cells with light chain restriction may provide additional evidence that supports a clonal and potentially malignant process.

Erythematous to violaceous nodules on the head and neck of older individuals are characteristic of both granuloma faciale and CBCL. Histologically, granuloma faciale is characterized by a dense cellular infiltrate, often with a nodular outline, occupying the mid dermis.² Granuloma faciale typically spares the immediate subepidermis and hair follicles, forming a grenz zone. The cellular infiltrate is polymorphic and consists of eosinophils and neutrophils with scattered plasma cells, mast cells, and lymphocytes in a vasculocentric distribution, eventually with chronic concentric fibrosis (Figure 2).

Leukemia cutis demonstrates a dermal infiltrate that contains atypical mononuclear cells (myeloblasts and myelocytes)(Figure 3).³ These markedly atypical mononuclear cells can have kidney bean-shaped nuclei and percolate through the dermal collagen, resembling single-file cells. They have increased nuclear to cytoplasmic ratios and occasionally have prominent nucleoli. Correlation with immunophenotypic and cytochemical studies is required for specific typing of the leukemic infiltrate.

Similar to primary CBCL, lymphomatoid papulosis (LyP) consists of erythematous papules or nodules that can occur anywhere on the body. In contrast to CBCL, the lesions of LyP classically self-resolve. However, approximately 10% to 20% of patients develop a malignant lymphoma, with mycosis fungoides, Hodgkin disease, and anaplastic large cell lymphoma being the most commonly associated.

Histologic examination of lesions of LyP classically demonstrates a wedge-shaped dermal infiltrate with variable epidermal changes (Figure 4). The wedge-shaped infiltrate is composed of large atypical cells. Three main types of lesions have been delineated: types A, B, and C. Type A is characterized by an increased number of cells with large vesicular nuclei with clumped chromatin, prominent nucleoli, and pronounced cytoplasm. Reed-Sternberg-like cells with an admixture of inflammatory cells including small lymphocytes, macrophages, neutrophils, and eosinophils also are present. Type B neoplastic cells vary in size and feature hyperchromatic, convoluted, or cerebriform nuclei. The infiltrate can be dense and bandlike with fewer cells resembling mycosis fungoides; type B LyP has neoplastic cells, not inflammatory cells. Finally, type C demonstrates solid sheets of large atypical cells resembling anaplastic large cell lymphoma. Immunohistochemically, the atypical cells often are CD4⁺ and CD8^- with variable loss of pan-T-cell antigens. The atypical cells of types A and C express CD30 reactivity.⁴

Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin that usually arises on sun-exposed skin in elderly patients with lesions that histologically and clinically resemble cutaneous lymphoma.⁵ It classically is composed of small, round to oval, basophilic cells with a vesicular nucleus and multiple small nucleoli. Apoptotic cells and mitoses often are present.⁶ One key finding that helps to differentiate MCC from lymphoma is the presence of finely dispersed salt-and-pepper chromatin and molded nuclear contour in MCC (Figure 5).

Immunophenotyping is important in the differentiation of these diagnoses. The atypical cells of LyP are positive for CD3, CD4, and CD30 but are negative for CD8. However, in type B LyP, the large CD30⁺ cells seen in the other types are not commonly seen. In contrast, MCC expresses reactivity with cytokeratins, in particular cytokeratin 20 and CAM5.2, classically in a paranuclear dotlike pattern. In keeping with MCC's neuroendocrine differentiation, the tumor cells will demonstrate reactivity with synaptophysin, chromogranin, and CD56. The immunohistochemistry for leukemia cutis varies depending on the type of leukemia. Acute myelomonocytic leukemia is positive for myeloperoxidase, CD13, CD33, and CD68. The immunophenotype of these marginal zone lymphoma cells is as follows: positive for CD20, CD79a, and Bcl-2; negative for Bcl-6, CD5, CD10, CD23, and cyclin D1 (Bcl-1).⁷ 

Primary Cutaneous B-cell Lymphoma

Cutaneous B-cell lymphomas (CBCLs) are a diverse but rare group of cutaneous lympho­proliferative neoplasms that make up approximately 20% of the total number of hematolymphoid neoplasms primary to the skin.¹ These lymphomas are comprised of neoplastic B cells in various stages of differentiation. As a whole, they are rare neoplasms that primarily involve the head, neck, trunk, arms, or legs.¹ Clinically, patients present with nontender, compressible, solitary, red to violaceous papules or nodules. Most CBCLs are considered low-grade malignancies with nonaggressive behavior and excellent prognosis; however, the diffuse large B-cell lymphomas, including but not limited to intravascular and leg type; lymphomatoid granulomatosis; and B-cell lymphoblastic lymphoma can act more aggressively.¹

Histopathologic examination of primary CBCL generally reveals a relatively normal epidermis accompanied by a nodular to diffuse monomorphic lymphocytic cellular infiltrate in the dermis that can occasionally extend into the subcutaneous tissue (quiz image). Although not specific for CBCLs, oftentimes there is an acellular portion of the superficial papillary dermis known as a grenz zone that can serve as a histopathologic clue to the diagnosis of a cutaneous lymphoproliferative disorder. The list of malignant B-cell neoplasms is extensive (eg, cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center lymphoma, diffuse large B-cell lymphoma, intravascular large B-cell lymphoma), and few are seen in the skin.

The most common type of CBCL is marginal zone B-cell lymphoma, which is considered to be a tumor of mucosa-associated (or skin-associated) lymphoid tissue. It is characterized by a monomorphous population of small mature lymphocytes showing characteristics of the B cells of the marginal zone of the lymph node. Some cells have the features of centrocytes/centroblasts (Figure 1) demonstrated by slightly irregular or indented nuclei and generous amounts of cytoplasm. Larger and more pleomorphic cells such as immunoblasts are similarly noted (Figure 1). The quiz image and Figure 1 demonstrate a cutaneous marginal zone B-cell lymphoma. A histomorphologic clue supporting a diagnosis of marginal zone B-cell lymphoma over reactive lymphoid hyperplasia is a B-cell predominate (B- to T-cell ratio of at least 3 to 1) infiltrate that is comprised of marginal zone-type cells. Immunohistochemistry demonstrating fewer differentiated B cells with light chain restriction may provide additional evidence that supports a clonal and potentially malignant process.

Erythematous to violaceous nodules on the head and neck of older individuals are characteristic of both granuloma faciale and CBCL. Histologically, granuloma faciale is characterized by a dense cellular infiltrate, often with a nodular outline, occupying the mid dermis.² Granuloma faciale typically spares the immediate subepidermis and hair follicles, forming a grenz zone. The cellular infiltrate is polymorphic and consists of eosinophils and neutrophils with scattered plasma cells, mast cells, and lymphocytes in a vasculocentric distribution, eventually with chronic concentric fibrosis (Figure 2).

Leukemia cutis demonstrates a dermal infiltrate that contains atypical mononuclear cells (myeloblasts and myelocytes)(Figure 3).³ These markedly atypical mononuclear cells can have kidney bean-shaped nuclei and percolate through the dermal collagen, resembling single-file cells. They have increased nuclear to cytoplasmic ratios and occasionally have prominent nucleoli. Correlation with immunophenotypic and cytochemical studies is required for specific typing of the leukemic infiltrate.

Similar to primary CBCL, lymphomatoid papulosis (LyP) consists of erythematous papules or nodules that can occur anywhere on the body. In contrast to CBCL, the lesions of LyP classically self-resolve. However, approximately 10% to 20% of patients develop a malignant lymphoma, with mycosis fungoides, Hodgkin disease, and anaplastic large cell lymphoma being the most commonly associated.

Histologic examination of lesions of LyP classically demonstrates a wedge-shaped dermal infiltrate with variable epidermal changes (Figure 4). The wedge-shaped infiltrate is composed of large atypical cells. Three main types of lesions have been delineated: types A, B, and C. Type A is characterized by an increased number of cells with large vesicular nuclei with clumped chromatin, prominent nucleoli, and pronounced cytoplasm. Reed-Sternberg-like cells with an admixture of inflammatory cells including small lymphocytes, macrophages, neutrophils, and eosinophils also are present. Type B neoplastic cells vary in size and feature hyperchromatic, convoluted, or cerebriform nuclei. The infiltrate can be dense and bandlike with fewer cells resembling mycosis fungoides; type B LyP has neoplastic cells, not inflammatory cells. Finally, type C demonstrates solid sheets of large atypical cells resembling anaplastic large cell lymphoma. Immunohistochemically, the atypical cells often are CD4⁺ and CD8^- with variable loss of pan-T-cell antigens. The atypical cells of types A and C express CD30 reactivity.⁴

Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin that usually arises on sun-exposed skin in elderly patients with lesions that histologically and clinically resemble cutaneous lymphoma.⁵ It classically is composed of small, round to oval, basophilic cells with a vesicular nucleus and multiple small nucleoli. Apoptotic cells and mitoses often are present.⁶ One key finding that helps to differentiate MCC from lymphoma is the presence of finely dispersed salt-and-pepper chromatin and molded nuclear contour in MCC (Figure 5).

Immunophenotyping is important in the differentiation of these diagnoses. The atypical cells of LyP are positive for CD3, CD4, and CD30 but are negative for CD8. However, in type B LyP, the large CD30⁺ cells seen in the other types are not commonly seen. In contrast, MCC expresses reactivity with cytokeratins, in particular cytokeratin 20 and CAM5.2, classically in a paranuclear dotlike pattern. In keeping with MCC's neuroendocrine differentiation, the tumor cells will demonstrate reactivity with synaptophysin, chromogranin, and CD56. The immunohistochemistry for leukemia cutis varies depending on the type of leukemia. Acute myelomonocytic leukemia is positive for myeloperoxidase, CD13, CD33, and CD68. The immunophenotype of these marginal zone lymphoma cells is as follows: positive for CD20, CD79a, and Bcl-2; negative for Bcl-6, CD5, CD10, CD23, and cyclin D1 (Bcl-1).⁷ 

Primary Cutaneous B-cell Lymphoma

Cutaneous B-cell lymphomas (CBCLs) are a diverse but rare group of cutaneous lympho­proliferative neoplasms that make up approximately 20% of the total number of hematolymphoid neoplasms primary to the skin.¹ These lymphomas are comprised of neoplastic B cells in various stages of differentiation. As a whole, they are rare neoplasms that primarily involve the head, neck, trunk, arms, or legs.¹ Clinically, patients present with nontender, compressible, solitary, red to violaceous papules or nodules. Most CBCLs are considered low-grade malignancies with nonaggressive behavior and excellent prognosis; however, the diffuse large B-cell lymphomas, including but not limited to intravascular and leg type; lymphomatoid granulomatosis; and B-cell lymphoblastic lymphoma can act more aggressively.¹

Histopathologic examination of primary CBCL generally reveals a relatively normal epidermis accompanied by a nodular to diffuse monomorphic lymphocytic cellular infiltrate in the dermis that can occasionally extend into the subcutaneous tissue (quiz image). Although not specific for CBCLs, oftentimes there is an acellular portion of the superficial papillary dermis known as a grenz zone that can serve as a histopathologic clue to the diagnosis of a cutaneous lymphoproliferative disorder. The list of malignant B-cell neoplasms is extensive (eg, cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center lymphoma, diffuse large B-cell lymphoma, intravascular large B-cell lymphoma), and few are seen in the skin.

The most common type of CBCL is marginal zone B-cell lymphoma, which is considered to be a tumor of mucosa-associated (or skin-associated) lymphoid tissue. It is characterized by a monomorphous population of small mature lymphocytes showing characteristics of the B cells of the marginal zone of the lymph node. Some cells have the features of centrocytes/centroblasts (Figure 1) demonstrated by slightly irregular or indented nuclei and generous amounts of cytoplasm. Larger and more pleomorphic cells such as immunoblasts are similarly noted (Figure 1). The quiz image and Figure 1 demonstrate a cutaneous marginal zone B-cell lymphoma. A histomorphologic clue supporting a diagnosis of marginal zone B-cell lymphoma over reactive lymphoid hyperplasia is a B-cell predominate (B- to T-cell ratio of at least 3 to 1) infiltrate that is comprised of marginal zone-type cells. Immunohistochemistry demonstrating fewer differentiated B cells with light chain restriction may provide additional evidence that supports a clonal and potentially malignant process.

Erythematous to violaceous nodules on the head and neck of older individuals are characteristic of both granuloma faciale and CBCL. Histologically, granuloma faciale is characterized by a dense cellular infiltrate, often with a nodular outline, occupying the mid dermis.² Granuloma faciale typically spares the immediate subepidermis and hair follicles, forming a grenz zone. The cellular infiltrate is polymorphic and consists of eosinophils and neutrophils with scattered plasma cells, mast cells, and lymphocytes in a vasculocentric distribution, eventually with chronic concentric fibrosis (Figure 2).

Leukemia cutis demonstrates a dermal infiltrate that contains atypical mononuclear cells (myeloblasts and myelocytes)(Figure 3).³ These markedly atypical mononuclear cells can have kidney bean-shaped nuclei and percolate through the dermal collagen, resembling single-file cells. They have increased nuclear to cytoplasmic ratios and occasionally have prominent nucleoli. Correlation with immunophenotypic and cytochemical studies is required for specific typing of the leukemic infiltrate.

Similar to primary CBCL, lymphomatoid papulosis (LyP) consists of erythematous papules or nodules that can occur anywhere on the body. In contrast to CBCL, the lesions of LyP classically self-resolve. However, approximately 10% to 20% of patients develop a malignant lymphoma, with mycosis fungoides, Hodgkin disease, and anaplastic large cell lymphoma being the most commonly associated.

Histologic examination of lesions of LyP classically demonstrates a wedge-shaped dermal infiltrate with variable epidermal changes (Figure 4). The wedge-shaped infiltrate is composed of large atypical cells. Three main types of lesions have been delineated: types A, B, and C. Type A is characterized by an increased number of cells with large vesicular nuclei with clumped chromatin, prominent nucleoli, and pronounced cytoplasm. Reed-Sternberg-like cells with an admixture of inflammatory cells including small lymphocytes, macrophages, neutrophils, and eosinophils also are present. Type B neoplastic cells vary in size and feature hyperchromatic, convoluted, or cerebriform nuclei. The infiltrate can be dense and bandlike with fewer cells resembling mycosis fungoides; type B LyP has neoplastic cells, not inflammatory cells. Finally, type C demonstrates solid sheets of large atypical cells resembling anaplastic large cell lymphoma. Immunohistochemically, the atypical cells often are CD4⁺ and CD8^- with variable loss of pan-T-cell antigens. The atypical cells of types A and C express CD30 reactivity.⁴

Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin that usually arises on sun-exposed skin in elderly patients with lesions that histologically and clinically resemble cutaneous lymphoma.⁵ It classically is composed of small, round to oval, basophilic cells with a vesicular nucleus and multiple small nucleoli. Apoptotic cells and mitoses often are present.⁶ One key finding that helps to differentiate MCC from lymphoma is the presence of finely dispersed salt-and-pepper chromatin and molded nuclear contour in MCC (Figure 5).

Immunophenotyping is important in the differentiation of these diagnoses. The atypical cells of LyP are positive for CD3, CD4, and CD30 but are negative for CD8. However, in type B LyP, the large CD30⁺ cells seen in the other types are not commonly seen. In contrast, MCC expresses reactivity with cytokeratins, in particular cytokeratin 20 and CAM5.2, classically in a paranuclear dotlike pattern. In keeping with MCC's neuroendocrine differentiation, the tumor cells will demonstrate reactivity with synaptophysin, chromogranin, and CD56. The immunohistochemistry for leukemia cutis varies depending on the type of leukemia. Acute myelomonocytic leukemia is positive for myeloperoxidase, CD13, CD33, and CD68. The immunophenotype of these marginal zone lymphoma cells is as follows: positive for CD20, CD79a, and Bcl-2; negative for Bcl-6, CD5, CD10, CD23, and cyclin D1 (Bcl-1).⁷ 

Epidermodysplasia Verruciformis

Epidermodysplasia verruciformis (EV) is a rare hereditary disorder that predisposes affected individuals to widespread infection with various forms of human papillomavirus (HPV). It is inherited in an autosomal-recessive pattern.¹ The first manifestations generally are seen in childhood. The clinical appearance of lesions can vary, at times mimicking other disease processes. Patients can present with flat wartlike papules resembling verruca plana distributed in sun-exposed areas. Another distinct presentation is multiple salmon-colored, hyperpigmented, or hypopigmented macules, papules, or plaques with overlying scale that can resemble tinea versicolor.^1,2 A large percentage of patients will go on to develop actinic keratosis and squamous cell carcinoma by 40 years of age.² The malignancies most commonly develop in sun-exposed areas, suggesting UV radiation as an important contributor to development along with HPV infection. Mutations in the EVER1 and EVER2 genes that code for transmembrane proteins on the endoplasmic reticulum that are involved in zinc transport lead to EV. The mutations lead to decreased zinc movement into the cytoplasm, which is thought to play a role in preventing HPV infection. The decreased protection against HPV leads to infections from both common subtypes and those that immunocompetent individuals would be resistant to, namely the β-genus HPV-5, -8, -9 and -20.^1,2 Immunosuppressed individuals, such as those with human immunodeficiency virus/AIDS, also are at an increased risk for infection with these HPV subtypes and generally have similar clinical and histological presentations.¹ It is important to promote sunscreen use for preventive care in patients with EV due to the increased risk for squamous cell carcinoma.

Histologically, the lesions in EV are composed of acanthosis and hyperkeratosis with keratinocytes arranged in clusters.^1,3 There is orthokeratosis and parakeratosis.¹ Scattered or clustered keratinocytes in the granular layer or upper stratum spinosum appear swollen with foamy blue-gray cytoplasm (quiz image and Figure 1).^1,4 The keratinocytes may become atypical and progress to squamous cell carcinoma, particularly in sun-exposed regions. Cell differentiation becomes disorganized and nuclei become enlarged and hyperchromatic.¹

Condyloma acuminatum will have pronounced acanthosis and hyperkeratosis with exophytic growth. Rounded parakeratosis is visible. The characteristic cell is the koilocyte, a keratinocyte that has an enlarged nucleus with areas of surrounding clearing, increased dark color in the nucleus, and wrinkled nuclear membrane (Figure 2).^1,3 True koilocytes may be rare in condyloma acuminatum.⁴ Other distinct features include coarse hypergranulosis and a compact stratum corneum.

Herpesvirus lesions typically demonstrate ballooning degeneration of keratinocytes.¹ They will become pale and fuse to form multinucleated giant cells, a feature not found in verruca. The nuclei will be slate gray with margination of the chromatin, which can be identified due to its increased basophilic appearance (Figure 3).^1,4 Inclusion bodies can be found, but unlike molluscum contagiosum (MC), these bodies are intranuclear as opposed to cytoplasmic.¹

The telltale Henderson-Patterson (molluscum) bodies can identify MC histologically.⁴ Located within keratinocytes, these cytoplasmic inclusions can vary in both color and size as they mature. As the keratinocytes develop outward, the molluscum bodies grow larger and become more eosinophilic (Figure 4).^1,4 Another feature of MC that can be used to differentiate it from EV is the scalloped borders located on lesions.⁴

On histology, verruca vulgaris will have pronounced acanthosis with orthokeratosis and vertical tiers of parakeratosis.^3,4 Growth is exophytic. The granular layer will have large irregular basophilic granules. Koilocytes may be seen. A distinctive feature is the papillomatosis with inward bending of rete ridges.^3,4 It is common to see invasion of tortuous blood vessels into the exophytic projections.³ In myrmecia (palmoplantar warts) it is common to see thrombosis of these vessels and inclusions of red cytoplasmic bodies (Figure 5).^1,4

Epidermodysplasia Verruciformis

Epidermodysplasia verruciformis (EV) is a rare hereditary disorder that predisposes affected individuals to widespread infection with various forms of human papillomavirus (HPV). It is inherited in an autosomal-recessive pattern.¹ The first manifestations generally are seen in childhood. The clinical appearance of lesions can vary, at times mimicking other disease processes. Patients can present with flat wartlike papules resembling verruca plana distributed in sun-exposed areas. Another distinct presentation is multiple salmon-colored, hyperpigmented, or hypopigmented macules, papules, or plaques with overlying scale that can resemble tinea versicolor.^1,2 A large percentage of patients will go on to develop actinic keratosis and squamous cell carcinoma by 40 years of age.² The malignancies most commonly develop in sun-exposed areas, suggesting UV radiation as an important contributor to development along with HPV infection. Mutations in the EVER1 and EVER2 genes that code for transmembrane proteins on the endoplasmic reticulum that are involved in zinc transport lead to EV. The mutations lead to decreased zinc movement into the cytoplasm, which is thought to play a role in preventing HPV infection. The decreased protection against HPV leads to infections from both common subtypes and those that immunocompetent individuals would be resistant to, namely the β-genus HPV-5, -8, -9 and -20.^1,2 Immunosuppressed individuals, such as those with human immunodeficiency virus/AIDS, also are at an increased risk for infection with these HPV subtypes and generally have similar clinical and histological presentations.¹ It is important to promote sunscreen use for preventive care in patients with EV due to the increased risk for squamous cell carcinoma.

Histologically, the lesions in EV are composed of acanthosis and hyperkeratosis with keratinocytes arranged in clusters.^1,3 There is orthokeratosis and parakeratosis.¹ Scattered or clustered keratinocytes in the granular layer or upper stratum spinosum appear swollen with foamy blue-gray cytoplasm (quiz image and Figure 1).^1,4 The keratinocytes may become atypical and progress to squamous cell carcinoma, particularly in sun-exposed regions. Cell differentiation becomes disorganized and nuclei become enlarged and hyperchromatic.¹

Condyloma acuminatum will have pronounced acanthosis and hyperkeratosis with exophytic growth. Rounded parakeratosis is visible. The characteristic cell is the koilocyte, a keratinocyte that has an enlarged nucleus with areas of surrounding clearing, increased dark color in the nucleus, and wrinkled nuclear membrane (Figure 2).^1,3 True koilocytes may be rare in condyloma acuminatum.⁴ Other distinct features include coarse hypergranulosis and a compact stratum corneum.

Herpesvirus lesions typically demonstrate ballooning degeneration of keratinocytes.¹ They will become pale and fuse to form multinucleated giant cells, a feature not found in verruca. The nuclei will be slate gray with margination of the chromatin, which can be identified due to its increased basophilic appearance (Figure 3).^1,4 Inclusion bodies can be found, but unlike molluscum contagiosum (MC), these bodies are intranuclear as opposed to cytoplasmic.¹

The telltale Henderson-Patterson (molluscum) bodies can identify MC histologically.⁴ Located within keratinocytes, these cytoplasmic inclusions can vary in both color and size as they mature. As the keratinocytes develop outward, the molluscum bodies grow larger and become more eosinophilic (Figure 4).^1,4 Another feature of MC that can be used to differentiate it from EV is the scalloped borders located on lesions.⁴

On histology, verruca vulgaris will have pronounced acanthosis with orthokeratosis and vertical tiers of parakeratosis.^3,4 Growth is exophytic. The granular layer will have large irregular basophilic granules. Koilocytes may be seen. A distinctive feature is the papillomatosis with inward bending of rete ridges.^3,4 It is common to see invasion of tortuous blood vessels into the exophytic projections.³ In myrmecia (palmoplantar warts) it is common to see thrombosis of these vessels and inclusions of red cytoplasmic bodies (Figure 5).^1,4

Epidermodysplasia Verruciformis

Epidermodysplasia verruciformis (EV) is a rare hereditary disorder that predisposes affected individuals to widespread infection with various forms of human papillomavirus (HPV). It is inherited in an autosomal-recessive pattern.¹ The first manifestations generally are seen in childhood. The clinical appearance of lesions can vary, at times mimicking other disease processes. Patients can present with flat wartlike papules resembling verruca plana distributed in sun-exposed areas. Another distinct presentation is multiple salmon-colored, hyperpigmented, or hypopigmented macules, papules, or plaques with overlying scale that can resemble tinea versicolor.^1,2 A large percentage of patients will go on to develop actinic keratosis and squamous cell carcinoma by 40 years of age.² The malignancies most commonly develop in sun-exposed areas, suggesting UV radiation as an important contributor to development along with HPV infection. Mutations in the EVER1 and EVER2 genes that code for transmembrane proteins on the endoplasmic reticulum that are involved in zinc transport lead to EV. The mutations lead to decreased zinc movement into the cytoplasm, which is thought to play a role in preventing HPV infection. The decreased protection against HPV leads to infections from both common subtypes and those that immunocompetent individuals would be resistant to, namely the β-genus HPV-5, -8, -9 and -20.^1,2 Immunosuppressed individuals, such as those with human immunodeficiency virus/AIDS, also are at an increased risk for infection with these HPV subtypes and generally have similar clinical and histological presentations.¹ It is important to promote sunscreen use for preventive care in patients with EV due to the increased risk for squamous cell carcinoma.

Histologically, the lesions in EV are composed of acanthosis and hyperkeratosis with keratinocytes arranged in clusters.^1,3 There is orthokeratosis and parakeratosis.¹ Scattered or clustered keratinocytes in the granular layer or upper stratum spinosum appear swollen with foamy blue-gray cytoplasm (quiz image and Figure 1).^1,4 The keratinocytes may become atypical and progress to squamous cell carcinoma, particularly in sun-exposed regions. Cell differentiation becomes disorganized and nuclei become enlarged and hyperchromatic.¹

Condyloma acuminatum will have pronounced acanthosis and hyperkeratosis with exophytic growth. Rounded parakeratosis is visible. The characteristic cell is the koilocyte, a keratinocyte that has an enlarged nucleus with areas of surrounding clearing, increased dark color in the nucleus, and wrinkled nuclear membrane (Figure 2).^1,3 True koilocytes may be rare in condyloma acuminatum.⁴ Other distinct features include coarse hypergranulosis and a compact stratum corneum.

Herpesvirus lesions typically demonstrate ballooning degeneration of keratinocytes.¹ They will become pale and fuse to form multinucleated giant cells, a feature not found in verruca. The nuclei will be slate gray with margination of the chromatin, which can be identified due to its increased basophilic appearance (Figure 3).^1,4 Inclusion bodies can be found, but unlike molluscum contagiosum (MC), these bodies are intranuclear as opposed to cytoplasmic.¹

The telltale Henderson-Patterson (molluscum) bodies can identify MC histologically.⁴ Located within keratinocytes, these cytoplasmic inclusions can vary in both color and size as they mature. As the keratinocytes develop outward, the molluscum bodies grow larger and become more eosinophilic (Figure 4).^1,4 Another feature of MC that can be used to differentiate it from EV is the scalloped borders located on lesions.⁴

On histology, verruca vulgaris will have pronounced acanthosis with orthokeratosis and vertical tiers of parakeratosis.^3,4 Growth is exophytic. The granular layer will have large irregular basophilic granules. Koilocytes may be seen. A distinctive feature is the papillomatosis with inward bending of rete ridges.^3,4 It is common to see invasion of tortuous blood vessels into the exophytic projections.³ In myrmecia (palmoplantar warts) it is common to see thrombosis of these vessels and inclusions of red cytoplasmic bodies (Figure 5).^1,4

The Diagnosis: Cutaneous Protothecosis

A 4-mm punch biopsy of the plaque on the right forearm was performed. The biopsy showed chronic inflammation with prominent histiocytes, foreign body giant cells, plasma cells, and abundant eosinophils (Figure 1). Grocott-Gomori methenamine-silver stain demonstrated abundant soccer ball-like or floretlike sporangia that were 3 to 11 μm, consistent with a diagnosis of protothecosis (Figure 2).

Cutaneous protothecosis is an infection caused by chlorophyll-lacking algae of the genus Prototheca.¹ It is ubiquitous in nature and can be isolated from various reservoirs such as trees, grass, water, and food sources.² Protothecosis is present worldwide and in the United States; it is most prevalent in the Southeast. Prototheca species are rare but often endemic in cattle and can cause bovine mastitis and enteritis.³ However, they are rare opportunistic infections in humans.

The pathogenesis of cutaneous protothecosis is largely unknown.⁴ However, most infections are thought to be caused by traumatic inoculation into subcutaneous tissues.^1,2 The majority of cases occur in patients older than 30 years. To date, approximately 160 cases have been reported in the literature worldwide.⁵ There are 3 main species of Prototheca, but almost all human infections are caused by Prototheca wickerhamii.² Clinically, most patients with protothecosis present with cutaneous findings, but olecranon bursitis and systemic forms also have been reported.¹

Risk factors for protothecosis include immunosuppression, most often due to steroids, in addition to malignancies, diabetes mellitus, and certain occupations.¹ The presentation can be variable from papules and plaques to even herpetiform appearances.⁴ Protothecosis usually affects the skin and soft tissues of exposed areas such as the extremities or the face.⁶ Diagnosis largely is made on detection of characteristic floretlike sporangia with a prominent cell wall on histopathological examination. Prototheca wickerhamii specifically produces a morula form of sporangia with endospores arranged symmetrically, giving it a characteristic soccer ball appearance.²

Treatment of protothecosis is difficult and remains controversial.¹ There are no established protothecosis treatment protocols or guidelines due to the small number of cases.⁷ In vitro studies have demonstrated sensitivity to amphotericin B and various azoles as well as a wide range of antibiotics.¹ Olecranon bursitis and small skin lesions can be treated by surgical excision. All other Prototheca infections require systemic treatment with azoles or  intravenous amphotericin B for immunocompromised patients or those with disseminated disease.⁵ However, failure to respond to medical management often occurs, requiring surgical excision.^1,6

Our patient was treated with a 3-month course of voriconazole but therapy failed and the plaque continued to expand. The patient underwent a wide excision that was repaired with a partial-thickness skin graft. Rebiopsy of the papule adjacent to the skin graft showed no further recurrence.

In conclusion, protothecosis generally is not clinically suspected and patients are subjected to various treatments without adequate results. A definitive diagnosis easily can be established with a skin biopsy, which can direct timely and appropriate treatment.

The Diagnosis: Cutaneous Protothecosis

A 4-mm punch biopsy of the plaque on the right forearm was performed. The biopsy showed chronic inflammation with prominent histiocytes, foreign body giant cells, plasma cells, and abundant eosinophils (Figure 1). Grocott-Gomori methenamine-silver stain demonstrated abundant soccer ball-like or floretlike sporangia that were 3 to 11 μm, consistent with a diagnosis of protothecosis (Figure 2).

Cutaneous protothecosis is an infection caused by chlorophyll-lacking algae of the genus Prototheca.¹ It is ubiquitous in nature and can be isolated from various reservoirs such as trees, grass, water, and food sources.² Protothecosis is present worldwide and in the United States; it is most prevalent in the Southeast. Prototheca species are rare but often endemic in cattle and can cause bovine mastitis and enteritis.³ However, they are rare opportunistic infections in humans.

The pathogenesis of cutaneous protothecosis is largely unknown.⁴ However, most infections are thought to be caused by traumatic inoculation into subcutaneous tissues.^1,2 The majority of cases occur in patients older than 30 years. To date, approximately 160 cases have been reported in the literature worldwide.⁵ There are 3 main species of Prototheca, but almost all human infections are caused by Prototheca wickerhamii.² Clinically, most patients with protothecosis present with cutaneous findings, but olecranon bursitis and systemic forms also have been reported.¹

Risk factors for protothecosis include immunosuppression, most often due to steroids, in addition to malignancies, diabetes mellitus, and certain occupations.¹ The presentation can be variable from papules and plaques to even herpetiform appearances.⁴ Protothecosis usually affects the skin and soft tissues of exposed areas such as the extremities or the face.⁶ Diagnosis largely is made on detection of characteristic floretlike sporangia with a prominent cell wall on histopathological examination. Prototheca wickerhamii specifically produces a morula form of sporangia with endospores arranged symmetrically, giving it a characteristic soccer ball appearance.²

Treatment of protothecosis is difficult and remains controversial.¹ There are no established protothecosis treatment protocols or guidelines due to the small number of cases.⁷ In vitro studies have demonstrated sensitivity to amphotericin B and various azoles as well as a wide range of antibiotics.¹ Olecranon bursitis and small skin lesions can be treated by surgical excision. All other Prototheca infections require systemic treatment with azoles or  intravenous amphotericin B for immunocompromised patients or those with disseminated disease.⁵ However, failure to respond to medical management often occurs, requiring surgical excision.^1,6

Our patient was treated with a 3-month course of voriconazole but therapy failed and the plaque continued to expand. The patient underwent a wide excision that was repaired with a partial-thickness skin graft. Rebiopsy of the papule adjacent to the skin graft showed no further recurrence.

In conclusion, protothecosis generally is not clinically suspected and patients are subjected to various treatments without adequate results. A definitive diagnosis easily can be established with a skin biopsy, which can direct timely and appropriate treatment.

The Diagnosis: Cutaneous Protothecosis

A 4-mm punch biopsy of the plaque on the right forearm was performed. The biopsy showed chronic inflammation with prominent histiocytes, foreign body giant cells, plasma cells, and abundant eosinophils (Figure 1). Grocott-Gomori methenamine-silver stain demonstrated abundant soccer ball-like or floretlike sporangia that were 3 to 11 μm, consistent with a diagnosis of protothecosis (Figure 2).

Cutaneous protothecosis is an infection caused by chlorophyll-lacking algae of the genus Prototheca.¹ It is ubiquitous in nature and can be isolated from various reservoirs such as trees, grass, water, and food sources.² Protothecosis is present worldwide and in the United States; it is most prevalent in the Southeast. Prototheca species are rare but often endemic in cattle and can cause bovine mastitis and enteritis.³ However, they are rare opportunistic infections in humans.

The pathogenesis of cutaneous protothecosis is largely unknown.⁴ However, most infections are thought to be caused by traumatic inoculation into subcutaneous tissues.^1,2 The majority of cases occur in patients older than 30 years. To date, approximately 160 cases have been reported in the literature worldwide.⁵ There are 3 main species of Prototheca, but almost all human infections are caused by Prototheca wickerhamii.² Clinically, most patients with protothecosis present with cutaneous findings, but olecranon bursitis and systemic forms also have been reported.¹

Risk factors for protothecosis include immunosuppression, most often due to steroids, in addition to malignancies, diabetes mellitus, and certain occupations.¹ The presentation can be variable from papules and plaques to even herpetiform appearances.⁴ Protothecosis usually affects the skin and soft tissues of exposed areas such as the extremities or the face.⁶ Diagnosis largely is made on detection of characteristic floretlike sporangia with a prominent cell wall on histopathological examination. Prototheca wickerhamii specifically produces a morula form of sporangia with endospores arranged symmetrically, giving it a characteristic soccer ball appearance.²

Treatment of protothecosis is difficult and remains controversial.¹ There are no established protothecosis treatment protocols or guidelines due to the small number of cases.⁷ In vitro studies have demonstrated sensitivity to amphotericin B and various azoles as well as a wide range of antibiotics.¹ Olecranon bursitis and small skin lesions can be treated by surgical excision. All other Prototheca infections require systemic treatment with azoles or  intravenous amphotericin B for immunocompromised patients or those with disseminated disease.⁵ However, failure to respond to medical management often occurs, requiring surgical excision.^1,6

Our patient was treated with a 3-month course of voriconazole but therapy failed and the plaque continued to expand. The patient underwent a wide excision that was repaired with a partial-thickness skin graft. Rebiopsy of the papule adjacent to the skin graft showed no further recurrence.

In conclusion, protothecosis generally is not clinically suspected and patients are subjected to various treatments without adequate results. A definitive diagnosis easily can be established with a skin biopsy, which can direct timely and appropriate treatment.