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The Diagnosis: Mycosis Fungoides

Physical examination revealed erythematous polycyclic and arcuate plaques with fine overlying scale on the right arm and shoulder (Figure 1). Mild wrinkling and telangiectasias were noted on the skin surrounding the lesions. Laboratory tests showed normal values for antinuclear antibodies, anti–Sjögren syndrome–related antigen A, and anti–Sjögren syndrome–related antigen B.

A skin biopsy of a plaque on the right upper arm showed enlarged pleomorphic lymphocytes arranged along the basal layer and in focal collections within the epidermis (Figure 2). Within the dermis were wiry bundles of collagen, a sparse superficial and patchy infiltrate of lymphocytes, and scattered large mononuclear cells (Figure 3). Immunoperoxidase staining revealed large intraepidermal lymphocytes positive for CD4 (Figure 4A) and CD5. Notably, these lymphocytes also stained positive for CD30 (Figure 4B). Staining for CD8, CD1a, CD56, and anaplastic lymphoma kinase was negative, with aberrant loss of CD3. The morphology and pattern of immunoreactivity supported the diagnosis of mycosis fungoides (MF).

Mycosis fungoides is the most common form of cutaneous T-cell lymphoma.¹ Its progression is classified in 3 stages: (1) early (patch) stage, (2) plaque stage, and (3) tumor stage. Conclusive diagnosis of early stage MF often is difficult due to its clinical features that are similar to more common benign dermatoses (eg, atopic dermatitis, psoriasis, lichen planus), leading to shortcomings in determining prognosis and selecting an appropriate treatment regimen. With this diagnositic difficulty in mind, guidelines have been created to aid in the diagnosis of early stage MF.²

Clinical features consistent with early stage MF include multiple erythematous, well-demarcated lesions with varying shapes that typically are greater than 5 cm in diameter.² Lesions usually are flat or thinly elevated and may exhibit slight scaling. As was noted in our patient, poikiloderma of the surrounding skin is fairly specific for early stage MF, as it is not a feature associated with common clinical mimics of MF (eg, atopic dermatitis, psoriasis, lichen planus). The distribution of skin lesions in non–sun-exposed areas is common. The eruption is persistent, though it may wax and wane in severity.²
 

Histopathologic examination is necessary to confirm a diagnosis of MF. Typically, early stage MF is marked by enlarged T lymphocytes within the epidermis as well as the papillary and superficial reticular dermis. Cerebriform nuclei are a key finding in the diagnosis of MF. Lymphocytes frequently are arranged linearly along the basal layer of the epidermis. Within the epidermis, clusters of atypical lymphocytes (Pautrier microabscesses) without spongiosis are uncommon but are a characteristic finding of MF if present.¹ Papillary dermal fibrosis also may be evident.²
 

Figure 4. Large intraepidermal lymphocytes were highlighted on CD4 (A) and CD30 immunostaining (B)(original magnification ×200 and ×200).

Immunostaining typically reveals positivity for CD3 and CD4, as well as for lymphocyte antigens CD2 and CD5.¹ CD30 positivity in early stage MF rarely has been reported in the literature.^3,4 Such cases appear histologically similarly to CD30‒negative cases in other respects. One study showed that the presence of CD30-positive lymphocytes does not alter the clinical course of MF.³ Another study found that, while epidermal CD30-postive lymphocytes had no prognostic relevance, an increased percentage of dermal CD30-positive cells was linked to a higher stage at diagnosis and worse overall prognosis.⁵ Pathogenesis underlying CD30 positivity in early MF is unknown. It is important to note that CD30-positive cells commonly are seen in lymphomatoid papulosis and anaplastic large cell lymphoma, as well as a variety of nonneoplastic conditions.^3,6,7

The Diagnosis: Mycosis Fungoides

Physical examination revealed erythematous polycyclic and arcuate plaques with fine overlying scale on the right arm and shoulder (Figure 1). Mild wrinkling and telangiectasias were noted on the skin surrounding the lesions. Laboratory tests showed normal values for antinuclear antibodies, anti–Sjögren syndrome–related antigen A, and anti–Sjögren syndrome–related antigen B.

A skin biopsy of a plaque on the right upper arm showed enlarged pleomorphic lymphocytes arranged along the basal layer and in focal collections within the epidermis (Figure 2). Within the dermis were wiry bundles of collagen, a sparse superficial and patchy infiltrate of lymphocytes, and scattered large mononuclear cells (Figure 3). Immunoperoxidase staining revealed large intraepidermal lymphocytes positive for CD4 (Figure 4A) and CD5. Notably, these lymphocytes also stained positive for CD30 (Figure 4B). Staining for CD8, CD1a, CD56, and anaplastic lymphoma kinase was negative, with aberrant loss of CD3. The morphology and pattern of immunoreactivity supported the diagnosis of mycosis fungoides (MF).

Mycosis fungoides is the most common form of cutaneous T-cell lymphoma.¹ Its progression is classified in 3 stages: (1) early (patch) stage, (2) plaque stage, and (3) tumor stage. Conclusive diagnosis of early stage MF often is difficult due to its clinical features that are similar to more common benign dermatoses (eg, atopic dermatitis, psoriasis, lichen planus), leading to shortcomings in determining prognosis and selecting an appropriate treatment regimen. With this diagnositic difficulty in mind, guidelines have been created to aid in the diagnosis of early stage MF.²

Clinical features consistent with early stage MF include multiple erythematous, well-demarcated lesions with varying shapes that typically are greater than 5 cm in diameter.² Lesions usually are flat or thinly elevated and may exhibit slight scaling. As was noted in our patient, poikiloderma of the surrounding skin is fairly specific for early stage MF, as it is not a feature associated with common clinical mimics of MF (eg, atopic dermatitis, psoriasis, lichen planus). The distribution of skin lesions in non–sun-exposed areas is common. The eruption is persistent, though it may wax and wane in severity.²
 

Histopathologic examination is necessary to confirm a diagnosis of MF. Typically, early stage MF is marked by enlarged T lymphocytes within the epidermis as well as the papillary and superficial reticular dermis. Cerebriform nuclei are a key finding in the diagnosis of MF. Lymphocytes frequently are arranged linearly along the basal layer of the epidermis. Within the epidermis, clusters of atypical lymphocytes (Pautrier microabscesses) without spongiosis are uncommon but are a characteristic finding of MF if present.¹ Papillary dermal fibrosis also may be evident.²
 

Figure 4. Large intraepidermal lymphocytes were highlighted on CD4 (A) and CD30 immunostaining (B)(original magnification ×200 and ×200).

Immunostaining typically reveals positivity for CD3 and CD4, as well as for lymphocyte antigens CD2 and CD5.¹ CD30 positivity in early stage MF rarely has been reported in the literature.^3,4 Such cases appear histologically similarly to CD30‒negative cases in other respects. One study showed that the presence of CD30-positive lymphocytes does not alter the clinical course of MF.³ Another study found that, while epidermal CD30-postive lymphocytes had no prognostic relevance, an increased percentage of dermal CD30-positive cells was linked to a higher stage at diagnosis and worse overall prognosis.⁵ Pathogenesis underlying CD30 positivity in early MF is unknown. It is important to note that CD30-positive cells commonly are seen in lymphomatoid papulosis and anaplastic large cell lymphoma, as well as a variety of nonneoplastic conditions.^3,6,7

The Diagnosis: Mycosis Fungoides

Physical examination revealed erythematous polycyclic and arcuate plaques with fine overlying scale on the right arm and shoulder (Figure 1). Mild wrinkling and telangiectasias were noted on the skin surrounding the lesions. Laboratory tests showed normal values for antinuclear antibodies, anti–Sjögren syndrome–related antigen A, and anti–Sjögren syndrome–related antigen B.

A skin biopsy of a plaque on the right upper arm showed enlarged pleomorphic lymphocytes arranged along the basal layer and in focal collections within the epidermis (Figure 2). Within the dermis were wiry bundles of collagen, a sparse superficial and patchy infiltrate of lymphocytes, and scattered large mononuclear cells (Figure 3). Immunoperoxidase staining revealed large intraepidermal lymphocytes positive for CD4 (Figure 4A) and CD5. Notably, these lymphocytes also stained positive for CD30 (Figure 4B). Staining for CD8, CD1a, CD56, and anaplastic lymphoma kinase was negative, with aberrant loss of CD3. The morphology and pattern of immunoreactivity supported the diagnosis of mycosis fungoides (MF).

Mycosis fungoides is the most common form of cutaneous T-cell lymphoma.¹ Its progression is classified in 3 stages: (1) early (patch) stage, (2) plaque stage, and (3) tumor stage. Conclusive diagnosis of early stage MF often is difficult due to its clinical features that are similar to more common benign dermatoses (eg, atopic dermatitis, psoriasis, lichen planus), leading to shortcomings in determining prognosis and selecting an appropriate treatment regimen. With this diagnositic difficulty in mind, guidelines have been created to aid in the diagnosis of early stage MF.²

Clinical features consistent with early stage MF include multiple erythematous, well-demarcated lesions with varying shapes that typically are greater than 5 cm in diameter.² Lesions usually are flat or thinly elevated and may exhibit slight scaling. As was noted in our patient, poikiloderma of the surrounding skin is fairly specific for early stage MF, as it is not a feature associated with common clinical mimics of MF (eg, atopic dermatitis, psoriasis, lichen planus). The distribution of skin lesions in non–sun-exposed areas is common. The eruption is persistent, though it may wax and wane in severity.²
 

Histopathologic examination is necessary to confirm a diagnosis of MF. Typically, early stage MF is marked by enlarged T lymphocytes within the epidermis as well as the papillary and superficial reticular dermis. Cerebriform nuclei are a key finding in the diagnosis of MF. Lymphocytes frequently are arranged linearly along the basal layer of the epidermis. Within the epidermis, clusters of atypical lymphocytes (Pautrier microabscesses) without spongiosis are uncommon but are a characteristic finding of MF if present.¹ Papillary dermal fibrosis also may be evident.²
 

Figure 4. Large intraepidermal lymphocytes were highlighted on CD4 (A) and CD30 immunostaining (B)(original magnification ×200 and ×200).

Immunostaining typically reveals positivity for CD3 and CD4, as well as for lymphocyte antigens CD2 and CD5.¹ CD30 positivity in early stage MF rarely has been reported in the literature.^3,4 Such cases appear histologically similarly to CD30‒negative cases in other respects. One study showed that the presence of CD30-positive lymphocytes does not alter the clinical course of MF.³ Another study found that, while epidermal CD30-postive lymphocytes had no prognostic relevance, an increased percentage of dermal CD30-positive cells was linked to a higher stage at diagnosis and worse overall prognosis.⁵ Pathogenesis underlying CD30 positivity in early MF is unknown. It is important to note that CD30-positive cells commonly are seen in lymphomatoid papulosis and anaplastic large cell lymphoma, as well as a variety of nonneoplastic conditions.^3,6,7

The Diagnosis: Neutrophilic Dermatosis of the Dorsal Hands

Neutrophilic dermatosis of the dorsal hands (NDDH) is considered to be an uncommon localized variant of Sweet syndrome (SS). The term pustular vasculitis originally was used to describe this condition by Strutton et al¹ in 1995 due to the presence of leukocytoclastic vasculitis on histology. In 2000, Galaria et al² suggested this eruption was a localized variant of SS based on clinical presentations that demonstrated associated fever and lack of necrotizing vasculitis and proposed the term neutrophilic dermatosis of the dorsal hands to describe the condition. Cases of similar cutaneous eruptions on the hands associated with fever, leukocytosis, elevated erythrocyte sedimentation rate, and leukocytoclasis have since been reported.^3-5 Some authors have concluded that these eruptions, previously termed atypical pyoderma gangrenosum and pustular vasculitis of the hands, represent a single disease entity and should be designated as NDDH.^3,4

Neutrophilic dermatosis of the dorsal hands characteristically presents with hemorrhagic pustular ulcerations limited to or predominantly located on the dorsal hands, as seen in our patient. Histopathologically, NDDH demonstrates a neutrophil-predominant infiltrate of the upper dermis and marked papillary dermal edema; a punch biopsy specimen from our patient was consistent with these features (Figure). Two punch biopsies were performed and were negative for fungus and acid-fast bacteria and positive for methicillin-sensitive Staphylococcus aureus. Vasculitis, if present, is more commonly seen in eruptions of longer duration (ie, months to years) and is thought to be secondary to the dense neutrophilic infiltrate and not a primary vasculitis.^3,6,7 Similar to classic SS, NDDH is inherently responsive to corticosteroid therapy. Successful treatment also has been reported with dapsone, colchicine, sulfapyridine, potassium iodide, intralesional and topical corticosteroids, and topical tacrolimus.^2-8 Oral minocycline has shown variable results.^3,4

Numerous case series have demonstrated that a majority of cases of NDDH are associated with hematologic or solid organ malignancies, myelodysplastic syndrome (MDS), inflammatory bowel disease, or other underlying systemic diseases.^3,5,9 It is important for dermatologists to recognize NDDH, distinguish it from localized infection, and perform the appropriate workup (eg, basic laboratory tests [complete blood count, complete metabolic panel], age-appropriate malignancy screening, colonoscopy, bone marrow biopsy) to exclude associated systemic diseases.

Our patient demonstrated characteristic clinical and histopathologic findings of NDDH in association with early MDS and possible common bile duct (CBD) malignancy. The lesions showed a rapid response to topical corticosteroid therapy. The initial differential diagnoses included NDDH or other neutrophilic dermatosis, phototoxic drug eruption, and atypical mycobacterial or fungal infection (cultures were negative in our patient). Physical examination and histopathologic findings along with the patient’s clinical course and rapid response to topical corticosteroid therapy supported the diagnosis of NDDH. Our patient’s multiple comorbidities, including macrocytic anemia, MDS, and potential CBD malignancy, presented a therapeutic challenge. Oral dapsone, an ideal steroid-sparing agent for neutrophilic dermatoses including NDDH, was avoided given its associated hematologic side effects including hemolysis, methemoglobinemia, and possible agranulocytosis. To date, the patient has not received any further treatment for MDS or the CBD mass and continues regular follow-up with hematology, gastroenterology, and dermatology.

This case highlights the importance of including NDDH in the differential diagnosis of papules and plaques on the hands, especially in patients with known malignancies, and emphasizes the association of neutrophilic dermatoses with malignancy and systemic disease. 

The Diagnosis: Neutrophilic Dermatosis of the Dorsal Hands

Neutrophilic dermatosis of the dorsal hands (NDDH) is considered to be an uncommon localized variant of Sweet syndrome (SS). The term pustular vasculitis originally was used to describe this condition by Strutton et al¹ in 1995 due to the presence of leukocytoclastic vasculitis on histology. In 2000, Galaria et al² suggested this eruption was a localized variant of SS based on clinical presentations that demonstrated associated fever and lack of necrotizing vasculitis and proposed the term neutrophilic dermatosis of the dorsal hands to describe the condition. Cases of similar cutaneous eruptions on the hands associated with fever, leukocytosis, elevated erythrocyte sedimentation rate, and leukocytoclasis have since been reported.^3-5 Some authors have concluded that these eruptions, previously termed atypical pyoderma gangrenosum and pustular vasculitis of the hands, represent a single disease entity and should be designated as NDDH.^3,4

Neutrophilic dermatosis of the dorsal hands characteristically presents with hemorrhagic pustular ulcerations limited to or predominantly located on the dorsal hands, as seen in our patient. Histopathologically, NDDH demonstrates a neutrophil-predominant infiltrate of the upper dermis and marked papillary dermal edema; a punch biopsy specimen from our patient was consistent with these features (Figure). Two punch biopsies were performed and were negative for fungus and acid-fast bacteria and positive for methicillin-sensitive Staphylococcus aureus. Vasculitis, if present, is more commonly seen in eruptions of longer duration (ie, months to years) and is thought to be secondary to the dense neutrophilic infiltrate and not a primary vasculitis.^3,6,7 Similar to classic SS, NDDH is inherently responsive to corticosteroid therapy. Successful treatment also has been reported with dapsone, colchicine, sulfapyridine, potassium iodide, intralesional and topical corticosteroids, and topical tacrolimus.^2-8 Oral minocycline has shown variable results.^3,4

Numerous case series have demonstrated that a majority of cases of NDDH are associated with hematologic or solid organ malignancies, myelodysplastic syndrome (MDS), inflammatory bowel disease, or other underlying systemic diseases.^3,5,9 It is important for dermatologists to recognize NDDH, distinguish it from localized infection, and perform the appropriate workup (eg, basic laboratory tests [complete blood count, complete metabolic panel], age-appropriate malignancy screening, colonoscopy, bone marrow biopsy) to exclude associated systemic diseases.

Our patient demonstrated characteristic clinical and histopathologic findings of NDDH in association with early MDS and possible common bile duct (CBD) malignancy. The lesions showed a rapid response to topical corticosteroid therapy. The initial differential diagnoses included NDDH or other neutrophilic dermatosis, phototoxic drug eruption, and atypical mycobacterial or fungal infection (cultures were negative in our patient). Physical examination and histopathologic findings along with the patient’s clinical course and rapid response to topical corticosteroid therapy supported the diagnosis of NDDH. Our patient’s multiple comorbidities, including macrocytic anemia, MDS, and potential CBD malignancy, presented a therapeutic challenge. Oral dapsone, an ideal steroid-sparing agent for neutrophilic dermatoses including NDDH, was avoided given its associated hematologic side effects including hemolysis, methemoglobinemia, and possible agranulocytosis. To date, the patient has not received any further treatment for MDS or the CBD mass and continues regular follow-up with hematology, gastroenterology, and dermatology.

This case highlights the importance of including NDDH in the differential diagnosis of papules and plaques on the hands, especially in patients with known malignancies, and emphasizes the association of neutrophilic dermatoses with malignancy and systemic disease. 

The Diagnosis: Neutrophilic Dermatosis of the Dorsal Hands

Neutrophilic dermatosis of the dorsal hands (NDDH) is considered to be an uncommon localized variant of Sweet syndrome (SS). The term pustular vasculitis originally was used to describe this condition by Strutton et al¹ in 1995 due to the presence of leukocytoclastic vasculitis on histology. In 2000, Galaria et al² suggested this eruption was a localized variant of SS based on clinical presentations that demonstrated associated fever and lack of necrotizing vasculitis and proposed the term neutrophilic dermatosis of the dorsal hands to describe the condition. Cases of similar cutaneous eruptions on the hands associated with fever, leukocytosis, elevated erythrocyte sedimentation rate, and leukocytoclasis have since been reported.^3-5 Some authors have concluded that these eruptions, previously termed atypical pyoderma gangrenosum and pustular vasculitis of the hands, represent a single disease entity and should be designated as NDDH.^3,4

Neutrophilic dermatosis of the dorsal hands characteristically presents with hemorrhagic pustular ulcerations limited to or predominantly located on the dorsal hands, as seen in our patient. Histopathologically, NDDH demonstrates a neutrophil-predominant infiltrate of the upper dermis and marked papillary dermal edema; a punch biopsy specimen from our patient was consistent with these features (Figure). Two punch biopsies were performed and were negative for fungus and acid-fast bacteria and positive for methicillin-sensitive Staphylococcus aureus. Vasculitis, if present, is more commonly seen in eruptions of longer duration (ie, months to years) and is thought to be secondary to the dense neutrophilic infiltrate and not a primary vasculitis.^3,6,7 Similar to classic SS, NDDH is inherently responsive to corticosteroid therapy. Successful treatment also has been reported with dapsone, colchicine, sulfapyridine, potassium iodide, intralesional and topical corticosteroids, and topical tacrolimus.^2-8 Oral minocycline has shown variable results.^3,4

Numerous case series have demonstrated that a majority of cases of NDDH are associated with hematologic or solid organ malignancies, myelodysplastic syndrome (MDS), inflammatory bowel disease, or other underlying systemic diseases.^3,5,9 It is important for dermatologists to recognize NDDH, distinguish it from localized infection, and perform the appropriate workup (eg, basic laboratory tests [complete blood count, complete metabolic panel], age-appropriate malignancy screening, colonoscopy, bone marrow biopsy) to exclude associated systemic diseases.

Our patient demonstrated characteristic clinical and histopathologic findings of NDDH in association with early MDS and possible common bile duct (CBD) malignancy. The lesions showed a rapid response to topical corticosteroid therapy. The initial differential diagnoses included NDDH or other neutrophilic dermatosis, phototoxic drug eruption, and atypical mycobacterial or fungal infection (cultures were negative in our patient). Physical examination and histopathologic findings along with the patient’s clinical course and rapid response to topical corticosteroid therapy supported the diagnosis of NDDH. Our patient’s multiple comorbidities, including macrocytic anemia, MDS, and potential CBD malignancy, presented a therapeutic challenge. Oral dapsone, an ideal steroid-sparing agent for neutrophilic dermatoses including NDDH, was avoided given its associated hematologic side effects including hemolysis, methemoglobinemia, and possible agranulocytosis. To date, the patient has not received any further treatment for MDS or the CBD mass and continues regular follow-up with hematology, gastroenterology, and dermatology.

This case highlights the importance of including NDDH in the differential diagnosis of papules and plaques on the hands, especially in patients with known malignancies, and emphasizes the association of neutrophilic dermatoses with malignancy and systemic disease. 

The Diagnosis: Hyperkeratosis Lenticularis Perstans

A shave biopsy of a lesion on the right leg was performed. Histopathology revealed a discrete papule with overlying compact hyperkeratosis. There was parakeratosis with an absent granular layer and a lichenoid lymphocytic infiltrate within the papillary dermis (Figure). Given the clinical context, these changes were consistent with a diagnosis of hyperkeratosis lenticularis perstans (HLP), also known as Flegel disease.

The patient was started on tretinoin cream 0.1% nightly for 3 months and triamcinolone ointment 0.1% as needed for pruritus but showed no clinical response. Given the benign nature of the condition and because the lesions were asymptomatic, additional treatment options were not pursued.

Originally described by Flegel¹ in 1958, HLP is a rare skin disorder commonly seen in white individuals with onset in the fourth or fifth decades of life.^1,2 While most cases are sporadic,^3-6 HLP also has been associated with autosomal dominant inheritance.^7-10

Patients with HLP typically present with multiple 1- to 5-mm reddish-brown, hyperkeratotic, scaly papules that reveal a moist, erythematous base with pinpoint bleeding upon removal of the scale. Lesions usually are distributed symmetrically and most commonly present on the extensor surfaces of the lower legs and dorsal feet.^1,2,7 Lesions also may appear on the extensor surfaces of the arms, pinna, periocular region, antecubital and popliteal fossae, and oral mucosa and also may present as pits on the palms and soles.^2,4,7,8 Furthermore, unilateral and localized variants of HLP have been described.^11,12 Hyperkeratosis lenticularis perstans usually is asymptomatic but can present with mild pruritus or burning.^3,5,13

The etiology and pathogenesis of HLP are unknown. Exposure to UV light has been implicated as an inciting factor¹⁴; however, reports of spontaneous resolution in the summer¹³ and upon treatment with psoralen plus UVA therapy¹⁵ make the role of UV light unclear. Furthermore, investigators disagree as to whether the primary pathogenic event in HLP is an inflammatory process or one of abnormal keratinization.^1,3,7,10 Fernandez-Flores and Manjon¹⁶ suggested HLP is an inflammatory process with periods of exacerbations and remissions after finding mounds of parakeratosis with neutrophils arranged in different strata in the stratum corneum.

Histologically, compact hyperkeratosis usually is noted, often with associated parakeratosis, epidermal atrophy with thinning or absence of the granular layer, and a bandlike lymphohistiocytic infiltrate in the papillary dermis.^1-3 Histopathologic differences between recent-onset versus longstanding lesions have been found, with old lesions lacking an inflammatory infiltrate.³ Furthermore, new lesions often show abnormalities in quantity and/or morphology of membrane-coating granules, also known as Odland bodies, in keratinocytes on electron microscopy,^3,10,17 while old lesions do not.³ Odland bodies are involved in normal desquamation, leading some to speculate on their role in HLP.¹⁰ Currently, it is unclear whether abnormalities in these organelles cause the retention hyperkeratosis seen in HLP or if such abnormalities are a secondary phenomenon.^3,17

There are questionable associations between HLP and diabetes mellitus type 2, hyperthyroidism, basal and squamous cell carcinomas of the skin, and gastrointestinal malignancy.^4,9,18 Our patient had a history of basal cell carcinoma on the face, diet-controlled diabetes mellitus, and hypothyroidism. Given the high prevalence of these diseases in the general population, however, it is difficult to ascertain whether a true association with HLP exists.

While HLP can slowly progress to involve additional body sites, it is overall a benign condition that does not require treatment. Therapeutic options are based on case reports, with no single treatment showing a consistent response. From review of the literature, therapies that have been most effective include dermabrasion, excision,¹⁹ topical 5-fluorouracil,^2,17,20 and oral retinoids.⁸ Hyperkeratosis lenticularis perstans generally is resistant to topical steroids, retinoids, and vitamin D₃ analogs, although success with betamethasone dipropionate,⁵ isotretinoin  
gel 0.05%,¹¹ and calcipotriol have been reported.⁶ A case of HLP with clinical response to psoralen plus UVA therapy also has been described.¹⁵

The Diagnosis: Hyperkeratosis Lenticularis Perstans

A shave biopsy of a lesion on the right leg was performed. Histopathology revealed a discrete papule with overlying compact hyperkeratosis. There was parakeratosis with an absent granular layer and a lichenoid lymphocytic infiltrate within the papillary dermis (Figure). Given the clinical context, these changes were consistent with a diagnosis of hyperkeratosis lenticularis perstans (HLP), also known as Flegel disease.

The patient was started on tretinoin cream 0.1% nightly for 3 months and triamcinolone ointment 0.1% as needed for pruritus but showed no clinical response. Given the benign nature of the condition and because the lesions were asymptomatic, additional treatment options were not pursued.

Originally described by Flegel¹ in 1958, HLP is a rare skin disorder commonly seen in white individuals with onset in the fourth or fifth decades of life.^1,2 While most cases are sporadic,^3-6 HLP also has been associated with autosomal dominant inheritance.^7-10

Patients with HLP typically present with multiple 1- to 5-mm reddish-brown, hyperkeratotic, scaly papules that reveal a moist, erythematous base with pinpoint bleeding upon removal of the scale. Lesions usually are distributed symmetrically and most commonly present on the extensor surfaces of the lower legs and dorsal feet.^1,2,7 Lesions also may appear on the extensor surfaces of the arms, pinna, periocular region, antecubital and popliteal fossae, and oral mucosa and also may present as pits on the palms and soles.^2,4,7,8 Furthermore, unilateral and localized variants of HLP have been described.^11,12 Hyperkeratosis lenticularis perstans usually is asymptomatic but can present with mild pruritus or burning.^3,5,13

The etiology and pathogenesis of HLP are unknown. Exposure to UV light has been implicated as an inciting factor¹⁴; however, reports of spontaneous resolution in the summer¹³ and upon treatment with psoralen plus UVA therapy¹⁵ make the role of UV light unclear. Furthermore, investigators disagree as to whether the primary pathogenic event in HLP is an inflammatory process or one of abnormal keratinization.^1,3,7,10 Fernandez-Flores and Manjon¹⁶ suggested HLP is an inflammatory process with periods of exacerbations and remissions after finding mounds of parakeratosis with neutrophils arranged in different strata in the stratum corneum.

Histologically, compact hyperkeratosis usually is noted, often with associated parakeratosis, epidermal atrophy with thinning or absence of the granular layer, and a bandlike lymphohistiocytic infiltrate in the papillary dermis.^1-3 Histopathologic differences between recent-onset versus longstanding lesions have been found, with old lesions lacking an inflammatory infiltrate.³ Furthermore, new lesions often show abnormalities in quantity and/or morphology of membrane-coating granules, also known as Odland bodies, in keratinocytes on electron microscopy,^3,10,17 while old lesions do not.³ Odland bodies are involved in normal desquamation, leading some to speculate on their role in HLP.¹⁰ Currently, it is unclear whether abnormalities in these organelles cause the retention hyperkeratosis seen in HLP or if such abnormalities are a secondary phenomenon.^3,17

There are questionable associations between HLP and diabetes mellitus type 2, hyperthyroidism, basal and squamous cell carcinomas of the skin, and gastrointestinal malignancy.^4,9,18 Our patient had a history of basal cell carcinoma on the face, diet-controlled diabetes mellitus, and hypothyroidism. Given the high prevalence of these diseases in the general population, however, it is difficult to ascertain whether a true association with HLP exists.

While HLP can slowly progress to involve additional body sites, it is overall a benign condition that does not require treatment. Therapeutic options are based on case reports, with no single treatment showing a consistent response. From review of the literature, therapies that have been most effective include dermabrasion, excision,¹⁹ topical 5-fluorouracil,^2,17,20 and oral retinoids.⁸ Hyperkeratosis lenticularis perstans generally is resistant to topical steroids, retinoids, and vitamin D₃ analogs, although success with betamethasone dipropionate,⁵ isotretinoin  
gel 0.05%,¹¹ and calcipotriol have been reported.⁶ A case of HLP with clinical response to psoralen plus UVA therapy also has been described.¹⁵

The Diagnosis: Hyperkeratosis Lenticularis Perstans

A shave biopsy of a lesion on the right leg was performed. Histopathology revealed a discrete papule with overlying compact hyperkeratosis. There was parakeratosis with an absent granular layer and a lichenoid lymphocytic infiltrate within the papillary dermis (Figure). Given the clinical context, these changes were consistent with a diagnosis of hyperkeratosis lenticularis perstans (HLP), also known as Flegel disease.

The patient was started on tretinoin cream 0.1% nightly for 3 months and triamcinolone ointment 0.1% as needed for pruritus but showed no clinical response. Given the benign nature of the condition and because the lesions were asymptomatic, additional treatment options were not pursued.

Originally described by Flegel¹ in 1958, HLP is a rare skin disorder commonly seen in white individuals with onset in the fourth or fifth decades of life.^1,2 While most cases are sporadic,^3-6 HLP also has been associated with autosomal dominant inheritance.^7-10

Patients with HLP typically present with multiple 1- to 5-mm reddish-brown, hyperkeratotic, scaly papules that reveal a moist, erythematous base with pinpoint bleeding upon removal of the scale. Lesions usually are distributed symmetrically and most commonly present on the extensor surfaces of the lower legs and dorsal feet.^1,2,7 Lesions also may appear on the extensor surfaces of the arms, pinna, periocular region, antecubital and popliteal fossae, and oral mucosa and also may present as pits on the palms and soles.^2,4,7,8 Furthermore, unilateral and localized variants of HLP have been described.^11,12 Hyperkeratosis lenticularis perstans usually is asymptomatic but can present with mild pruritus or burning.^3,5,13

The etiology and pathogenesis of HLP are unknown. Exposure to UV light has been implicated as an inciting factor¹⁴; however, reports of spontaneous resolution in the summer¹³ and upon treatment with psoralen plus UVA therapy¹⁵ make the role of UV light unclear. Furthermore, investigators disagree as to whether the primary pathogenic event in HLP is an inflammatory process or one of abnormal keratinization.^1,3,7,10 Fernandez-Flores and Manjon¹⁶ suggested HLP is an inflammatory process with periods of exacerbations and remissions after finding mounds of parakeratosis with neutrophils arranged in different strata in the stratum corneum.

Histologically, compact hyperkeratosis usually is noted, often with associated parakeratosis, epidermal atrophy with thinning or absence of the granular layer, and a bandlike lymphohistiocytic infiltrate in the papillary dermis.^1-3 Histopathologic differences between recent-onset versus longstanding lesions have been found, with old lesions lacking an inflammatory infiltrate.³ Furthermore, new lesions often show abnormalities in quantity and/or morphology of membrane-coating granules, also known as Odland bodies, in keratinocytes on electron microscopy,^3,10,17 while old lesions do not.³ Odland bodies are involved in normal desquamation, leading some to speculate on their role in HLP.¹⁰ Currently, it is unclear whether abnormalities in these organelles cause the retention hyperkeratosis seen in HLP or if such abnormalities are a secondary phenomenon.^3,17

There are questionable associations between HLP and diabetes mellitus type 2, hyperthyroidism, basal and squamous cell carcinomas of the skin, and gastrointestinal malignancy.^4,9,18 Our patient had a history of basal cell carcinoma on the face, diet-controlled diabetes mellitus, and hypothyroidism. Given the high prevalence of these diseases in the general population, however, it is difficult to ascertain whether a true association with HLP exists.

While HLP can slowly progress to involve additional body sites, it is overall a benign condition that does not require treatment. Therapeutic options are based on case reports, with no single treatment showing a consistent response. From review of the literature, therapies that have been most effective include dermabrasion, excision,¹⁹ topical 5-fluorouracil,^2,17,20 and oral retinoids.⁸ Hyperkeratosis lenticularis perstans generally is resistant to topical steroids, retinoids, and vitamin D₃ analogs, although success with betamethasone dipropionate,⁵ isotretinoin  
gel 0.05%,¹¹ and calcipotriol have been reported.⁶ A case of HLP with clinical response to psoralen plus UVA therapy also has been described.¹⁵

The Diagnosis: Herpes Zoster

Herpes zoster is a common infection that clinically presents with moderate to intense pain in the involved dermatome (1–3 days before the outbreak¹) followed by a unilateral dermatomal eruption. The most common sites of involvement include the trunk (dermatomes T3–L2) and upper face (dermatome V1).² Herpes zoster characteristically begins as erythematous macules and papules that progress to vesicles and sometimes pustules, which subsequently crust over (7–10 days after the initial outbreak).¹ Regional lymphadenopathy is present in most cases. Due to the classic presentation of herpes zoster, clinical diagnosis is the mainstay for most cases. Although it can present in any age group, herpes zoster is most commonly associated with advancing age.³

During the course of primary varicella infection, the herpes virus spreads from infected lesions to the contiguous endings of sensory nerves and travels to the dorsal root ganglion cells where it remains latent.¹ It is hypothesized that cell-mediated immunity suppresses viral activity and maintains viral latency. A decline in varicella zoster virus–specific cell-mediated immunity can result in reactivation of the latent virus.¹ The virus is then transported to the skin from the dorsal root ganglion via myelinated nerves, which terminate at the isthmus of hair follicles, and subsequent infection of the folliculosebaceous unit occurs.⁴

Laboratory tests that can assist in the diagnosis of herpes zoster, especially atypical cases, include Tzanck smear and viral culture of the vesicle fluid.¹ When vesicles are not present, biopsy of the lesion followed by immunohistochemical staining and polymerase chain reaction assay can aid in the diagnosis. The differential diagnosis for our patient included pseudolymphoma, herpes simplex virus, lymphomatoid papulosis, sarcoidosis, trigeminal trophic syndrome, and Sweet syndrome.

Vesicles were not present in our patient, but the dermatomal nature of the eruption and the pain she experienced made the clinical scenario suspicious for herpes zoster. A 4-mm punch biopsy of a single folliculosebaceous unit revealed herpetic, cytopathic features including prominent keratinocyte necrosis involving sebaceous, isthmic, and infundibular epithelium; ballooning of epithelial cells with steel gray nuclei; and multinucleation with nuclear molding (Figure 1). Strong nuclear and cytoplasmic staining was seen in the affected keratinocytes under anti–varicella zoster virus immunohistochemical analysis (Figure 2). Staining for herpes simplex virus types 1 and 2 was negative. Within days of starting valacyclovir 1000 mg (every 8 hours for 1 week), the patient’s symptoms resolved.
 

Atypical presentations of herpes zoster (eg, presentations that are not completely dermatomal) are becoming more common. Herpetic infections should always be in the differential diagnosis for cutaneous ulcerations. Misdiagnosis of herpes zoster due to atypical features is common and can delay prompt and adequate treatment.

The Diagnosis: Herpes Zoster

Herpes zoster is a common infection that clinically presents with moderate to intense pain in the involved dermatome (1–3 days before the outbreak¹) followed by a unilateral dermatomal eruption. The most common sites of involvement include the trunk (dermatomes T3–L2) and upper face (dermatome V1).² Herpes zoster characteristically begins as erythematous macules and papules that progress to vesicles and sometimes pustules, which subsequently crust over (7–10 days after the initial outbreak).¹ Regional lymphadenopathy is present in most cases. Due to the classic presentation of herpes zoster, clinical diagnosis is the mainstay for most cases. Although it can present in any age group, herpes zoster is most commonly associated with advancing age.³

During the course of primary varicella infection, the herpes virus spreads from infected lesions to the contiguous endings of sensory nerves and travels to the dorsal root ganglion cells where it remains latent.¹ It is hypothesized that cell-mediated immunity suppresses viral activity and maintains viral latency. A decline in varicella zoster virus–specific cell-mediated immunity can result in reactivation of the latent virus.¹ The virus is then transported to the skin from the dorsal root ganglion via myelinated nerves, which terminate at the isthmus of hair follicles, and subsequent infection of the folliculosebaceous unit occurs.⁴

Laboratory tests that can assist in the diagnosis of herpes zoster, especially atypical cases, include Tzanck smear and viral culture of the vesicle fluid.¹ When vesicles are not present, biopsy of the lesion followed by immunohistochemical staining and polymerase chain reaction assay can aid in the diagnosis. The differential diagnosis for our patient included pseudolymphoma, herpes simplex virus, lymphomatoid papulosis, sarcoidosis, trigeminal trophic syndrome, and Sweet syndrome.

Vesicles were not present in our patient, but the dermatomal nature of the eruption and the pain she experienced made the clinical scenario suspicious for herpes zoster. A 4-mm punch biopsy of a single folliculosebaceous unit revealed herpetic, cytopathic features including prominent keratinocyte necrosis involving sebaceous, isthmic, and infundibular epithelium; ballooning of epithelial cells with steel gray nuclei; and multinucleation with nuclear molding (Figure 1). Strong nuclear and cytoplasmic staining was seen in the affected keratinocytes under anti–varicella zoster virus immunohistochemical analysis (Figure 2). Staining for herpes simplex virus types 1 and 2 was negative. Within days of starting valacyclovir 1000 mg (every 8 hours for 1 week), the patient’s symptoms resolved.
 

Atypical presentations of herpes zoster (eg, presentations that are not completely dermatomal) are becoming more common. Herpetic infections should always be in the differential diagnosis for cutaneous ulcerations. Misdiagnosis of herpes zoster due to atypical features is common and can delay prompt and adequate treatment.

The Diagnosis: Herpes Zoster

Herpes zoster is a common infection that clinically presents with moderate to intense pain in the involved dermatome (1–3 days before the outbreak¹) followed by a unilateral dermatomal eruption. The most common sites of involvement include the trunk (dermatomes T3–L2) and upper face (dermatome V1).² Herpes zoster characteristically begins as erythematous macules and papules that progress to vesicles and sometimes pustules, which subsequently crust over (7–10 days after the initial outbreak).¹ Regional lymphadenopathy is present in most cases. Due to the classic presentation of herpes zoster, clinical diagnosis is the mainstay for most cases. Although it can present in any age group, herpes zoster is most commonly associated with advancing age.³

During the course of primary varicella infection, the herpes virus spreads from infected lesions to the contiguous endings of sensory nerves and travels to the dorsal root ganglion cells where it remains latent.¹ It is hypothesized that cell-mediated immunity suppresses viral activity and maintains viral latency. A decline in varicella zoster virus–specific cell-mediated immunity can result in reactivation of the latent virus.¹ The virus is then transported to the skin from the dorsal root ganglion via myelinated nerves, which terminate at the isthmus of hair follicles, and subsequent infection of the folliculosebaceous unit occurs.⁴

Laboratory tests that can assist in the diagnosis of herpes zoster, especially atypical cases, include Tzanck smear and viral culture of the vesicle fluid.¹ When vesicles are not present, biopsy of the lesion followed by immunohistochemical staining and polymerase chain reaction assay can aid in the diagnosis. The differential diagnosis for our patient included pseudolymphoma, herpes simplex virus, lymphomatoid papulosis, sarcoidosis, trigeminal trophic syndrome, and Sweet syndrome.

Vesicles were not present in our patient, but the dermatomal nature of the eruption and the pain she experienced made the clinical scenario suspicious for herpes zoster. A 4-mm punch biopsy of a single folliculosebaceous unit revealed herpetic, cytopathic features including prominent keratinocyte necrosis involving sebaceous, isthmic, and infundibular epithelium; ballooning of epithelial cells with steel gray nuclei; and multinucleation with nuclear molding (Figure 1). Strong nuclear and cytoplasmic staining was seen in the affected keratinocytes under anti–varicella zoster virus immunohistochemical analysis (Figure 2). Staining for herpes simplex virus types 1 and 2 was negative. Within days of starting valacyclovir 1000 mg (every 8 hours for 1 week), the patient’s symptoms resolved.
 

Atypical presentations of herpes zoster (eg, presentations that are not completely dermatomal) are becoming more common. Herpetic infections should always be in the differential diagnosis for cutaneous ulcerations. Misdiagnosis of herpes zoster due to atypical features is common and can delay prompt and adequate treatment.

The Diagnosis: Acrodermatitis Continua of Hallopeau

Acrodermatitis continua of Hallopeau (ACH) is considered to be a form of acropustular psoriasis that presents as a sterile, pustular eruption initially affecting the fingertips and/or toes.¹ The slow-growing pustules typically progress locally and can lead to onychodystrophy and/or osteolysis of the underlying bone.^2,3 Most commonly affecting adult women, ACH often begins following local trauma to or infection of a single digit.⁴ As the disease progresses proximally, the small pustules burst, leaving a shiny, erythematous surface on which new pustules can develop. These pustules have a tendency to amalgamate, leading to the characteristic clinical finding of lakes of pus. Pustules frequently appear on the nail matrix and nail bed presenting as severe onychodystrophy and ultimately anonychia.^5,6 Rarely, ACH can be associated with generalized pustular psoriasis as well as conjunctivitis, balanitis, and fissuring or annulus migrans of the tongue.^2,7

Diagnosis can be established based on clinical findings, biopsy, and bacterial and fungal cultures revealing sterile pustules.^8,9 Histologic findings are similar to those seen in pustular psoriasis, demonstrating subcorneal neutrophilic pustules, Munro microabscesses, and dilated blood vessels with lymphocytic infiltrate in the papillary dermis.¹⁰

Due to the refractory nature of the disease, there are no recommended guidelines for treatment of ACH. Most successful treatment regimens consist of topical psoriasis medications combined with systemic psoriatic therapies such as cyclosporine, methotrexate, acitretin, or biologic therapy.^8,11-16 Our patient achieved satisfactory clinical improvement with clobetasol propionate ointment 0.05% twice daily alternating with calcipotriene cream 0.005% twice daily.

The Diagnosis: Acrodermatitis Continua of Hallopeau

Acrodermatitis continua of Hallopeau (ACH) is considered to be a form of acropustular psoriasis that presents as a sterile, pustular eruption initially affecting the fingertips and/or toes.¹ The slow-growing pustules typically progress locally and can lead to onychodystrophy and/or osteolysis of the underlying bone.^2,3 Most commonly affecting adult women, ACH often begins following local trauma to or infection of a single digit.⁴ As the disease progresses proximally, the small pustules burst, leaving a shiny, erythematous surface on which new pustules can develop. These pustules have a tendency to amalgamate, leading to the characteristic clinical finding of lakes of pus. Pustules frequently appear on the nail matrix and nail bed presenting as severe onychodystrophy and ultimately anonychia.^5,6 Rarely, ACH can be associated with generalized pustular psoriasis as well as conjunctivitis, balanitis, and fissuring or annulus migrans of the tongue.^2,7

Diagnosis can be established based on clinical findings, biopsy, and bacterial and fungal cultures revealing sterile pustules.^8,9 Histologic findings are similar to those seen in pustular psoriasis, demonstrating subcorneal neutrophilic pustules, Munro microabscesses, and dilated blood vessels with lymphocytic infiltrate in the papillary dermis.¹⁰

Due to the refractory nature of the disease, there are no recommended guidelines for treatment of ACH. Most successful treatment regimens consist of topical psoriasis medications combined with systemic psoriatic therapies such as cyclosporine, methotrexate, acitretin, or biologic therapy.^8,11-16 Our patient achieved satisfactory clinical improvement with clobetasol propionate ointment 0.05% twice daily alternating with calcipotriene cream 0.005% twice daily.

The Diagnosis: Acrodermatitis Continua of Hallopeau

Acrodermatitis continua of Hallopeau (ACH) is considered to be a form of acropustular psoriasis that presents as a sterile, pustular eruption initially affecting the fingertips and/or toes.¹ The slow-growing pustules typically progress locally and can lead to onychodystrophy and/or osteolysis of the underlying bone.^2,3 Most commonly affecting adult women, ACH often begins following local trauma to or infection of a single digit.⁴ As the disease progresses proximally, the small pustules burst, leaving a shiny, erythematous surface on which new pustules can develop. These pustules have a tendency to amalgamate, leading to the characteristic clinical finding of lakes of pus. Pustules frequently appear on the nail matrix and nail bed presenting as severe onychodystrophy and ultimately anonychia.^5,6 Rarely, ACH can be associated with generalized pustular psoriasis as well as conjunctivitis, balanitis, and fissuring or annulus migrans of the tongue.^2,7

Diagnosis can be established based on clinical findings, biopsy, and bacterial and fungal cultures revealing sterile pustules.^8,9 Histologic findings are similar to those seen in pustular psoriasis, demonstrating subcorneal neutrophilic pustules, Munro microabscesses, and dilated blood vessels with lymphocytic infiltrate in the papillary dermis.¹⁰

Due to the refractory nature of the disease, there are no recommended guidelines for treatment of ACH. Most successful treatment regimens consist of topical psoriasis medications combined with systemic psoriatic therapies such as cyclosporine, methotrexate, acitretin, or biologic therapy.^8,11-16 Our patient achieved satisfactory clinical improvement with clobetasol propionate ointment 0.05% twice daily alternating with calcipotriene cream 0.005% twice daily.

The Diagnosis: Tinea Corporis

Although contact dermatitis from the metal on the back of the watch was suspected, many modern wrist watches are made with stainless steel rather than nickel, which is a common contact allergen; therefore, other diagnoses were considered in the differential including irritant contact dermatitis, psoriasis, and tinea infection. A potassium hydroxide (KOH) preparation was performed to rule out tinea infection. Unexpectedly, the KOH preparation was positive for fungal hyphae, confirming a diagnosis of tinea corporis. The patient was treated with clotrimazole cream 1% twice daily for 3 weeks during which time the rash completely resolved.

We present this case to stress the importance of performing KOH preparations even when the likelihood of tinea infection seems remote. At our institution, we teach our residents, “If it’s scaly, scrape it.” This adage has served us well. Tinea corporis may be mistaken for many other skin diseases, including eczema, psoriasis, and seborrheic dermatitis.¹ A KOH preparation often is a helpful tool in confirming the diagnosis and should be performed when a dermatophyte infection is suspected. The KOH preparation is the most sensitive diagnostic test used to confirm dermatophyte infection, with 90% of infections showing positive results.^2,3

Tinea infections may occur anywhere on the body, but areas that are prone to excessive heat and/or moisture are particularly susceptible.⁴ Dermatophyte infections typically present as annular, scaly, pruritic patches or plaques often with central clearing and an active border.¹ In our patient, the lesion showed characteristics that were suggestive of a dermatophyte infection but was somewhat atypical in appearance, as it lacked central clearing (Figure). The 3 genera of dermatophytes—Trichophyton, Microsporum, and Epidermophyton—are common causes of fungal infections.² The pathogenesis of dermatophytosis is the synthesis of keratinases that digest keratin and sustain the presence of the fungi. Local factors such as sweating and occlusion facilitate the activity of these organisms.² In our case, the pathogenesis was believed to be due to the entrapment of moisture behind the patient’s watch, creating a favorable environment for fungal growth.

The Diagnosis: Tinea Corporis

Although contact dermatitis from the metal on the back of the watch was suspected, many modern wrist watches are made with stainless steel rather than nickel, which is a common contact allergen; therefore, other diagnoses were considered in the differential including irritant contact dermatitis, psoriasis, and tinea infection. A potassium hydroxide (KOH) preparation was performed to rule out tinea infection. Unexpectedly, the KOH preparation was positive for fungal hyphae, confirming a diagnosis of tinea corporis. The patient was treated with clotrimazole cream 1% twice daily for 3 weeks during which time the rash completely resolved.

We present this case to stress the importance of performing KOH preparations even when the likelihood of tinea infection seems remote. At our institution, we teach our residents, “If it’s scaly, scrape it.” This adage has served us well. Tinea corporis may be mistaken for many other skin diseases, including eczema, psoriasis, and seborrheic dermatitis.¹ A KOH preparation often is a helpful tool in confirming the diagnosis and should be performed when a dermatophyte infection is suspected. The KOH preparation is the most sensitive diagnostic test used to confirm dermatophyte infection, with 90% of infections showing positive results.^2,3

Tinea infections may occur anywhere on the body, but areas that are prone to excessive heat and/or moisture are particularly susceptible.⁴ Dermatophyte infections typically present as annular, scaly, pruritic patches or plaques often with central clearing and an active border.¹ In our patient, the lesion showed characteristics that were suggestive of a dermatophyte infection but was somewhat atypical in appearance, as it lacked central clearing (Figure). The 3 genera of dermatophytes—Trichophyton, Microsporum, and Epidermophyton—are common causes of fungal infections.² The pathogenesis of dermatophytosis is the synthesis of keratinases that digest keratin and sustain the presence of the fungi. Local factors such as sweating and occlusion facilitate the activity of these organisms.² In our case, the pathogenesis was believed to be due to the entrapment of moisture behind the patient’s watch, creating a favorable environment for fungal growth.

The Diagnosis: Tinea Corporis

Although contact dermatitis from the metal on the back of the watch was suspected, many modern wrist watches are made with stainless steel rather than nickel, which is a common contact allergen; therefore, other diagnoses were considered in the differential including irritant contact dermatitis, psoriasis, and tinea infection. A potassium hydroxide (KOH) preparation was performed to rule out tinea infection. Unexpectedly, the KOH preparation was positive for fungal hyphae, confirming a diagnosis of tinea corporis. The patient was treated with clotrimazole cream 1% twice daily for 3 weeks during which time the rash completely resolved.

We present this case to stress the importance of performing KOH preparations even when the likelihood of tinea infection seems remote. At our institution, we teach our residents, “If it’s scaly, scrape it.” This adage has served us well. Tinea corporis may be mistaken for many other skin diseases, including eczema, psoriasis, and seborrheic dermatitis.¹ A KOH preparation often is a helpful tool in confirming the diagnosis and should be performed when a dermatophyte infection is suspected. The KOH preparation is the most sensitive diagnostic test used to confirm dermatophyte infection, with 90% of infections showing positive results.^2,3

Tinea infections may occur anywhere on the body, but areas that are prone to excessive heat and/or moisture are particularly susceptible.⁴ Dermatophyte infections typically present as annular, scaly, pruritic patches or plaques often with central clearing and an active border.¹ In our patient, the lesion showed characteristics that were suggestive of a dermatophyte infection but was somewhat atypical in appearance, as it lacked central clearing (Figure). The 3 genera of dermatophytes—Trichophyton, Microsporum, and Epidermophyton—are common causes of fungal infections.² The pathogenesis of dermatophytosis is the synthesis of keratinases that digest keratin and sustain the presence of the fungi. Local factors such as sweating and occlusion facilitate the activity of these organisms.² In our case, the pathogenesis was believed to be due to the entrapment of moisture behind the patient’s watch, creating a favorable environment for fungal growth.

The Diagnosis: Agminated Blue Nevus

Agminated blue nevus is a rare melanocytic nevus that characteristically presents as a group of multiple small, bluish papules occurring in a well-circumscribed area.¹ It also has been referred to as a plaque-type nevus^2,3 and an eruptive blue nevus.⁴ Originally described by Upshaw et al² in 1947, agminated blue nevi may be congenital or arise in early childhood and almost always occur on the trunk. The skin between the papules often is unaffected or sometimes may show bluish or brown pigmentation.⁴ Agminated blue nevi usually are smaller than 10 cm in diameter; however, rare cases have measured up to 24 cm.^1,4-6 The incidence of agminated blue nevi is 2 times higher in males than in females.¹

A biopsy of the lesion revealed pigmented dendritic melanocytes admixed with melanophages, forming fascicles and bundles (A)(H&E, original magnification ×10). In some areas the dermis was uninvolved. Higher magnification showed dendritic and epithelioid melanocytes extending down along the adnexal structures (B)(H&E, original magnification ×40).

Histopathologically, agminated blue nevi typically demonstrate the features of common and/or cellular blue nevi. Cytologic atypia and mitoses are rare.¹ The degree of cellularity and pigmentation of the lesions is variable, and the presence of subcutaneous cellular nodules also has been described.⁵

In our patient, histologic evaluation revealed foci of diffuse dermal spindle cell proliferation composed of heavily pigmented dendritic melanocytes admixed with melanophages in a fibrotic stroma (Figure, A). The dermis was uninvolved in some areas and the melanocytes were epithelioid and formed fascicles and bundles that extended down adnexal structures in other areas (Figure, B). Junctional involvement of melanocytes, cellular atypia, and mitoses were not identified. Our case demonstrated a combination of histologic findings of a cellular blue nevus as well as features reminiscent of a deep penetrating nevus. The differential diagnosis of agminated blue nevus includes agminated Spitz nevus arising in a speckled lentiginous nevus,⁷ dermal melanocytosis, melanoma, and pilar neurocristic hamartoma. Pilar neurocristic hamartomas may resemble plaque-type blue nevi; however, the former show a predilection for the scalp, histologically demonstrate features that overlap with blue nevi and congenital nevi, and are associated with neural structures that show Schwannian differentiation.⁸ Agminated blue nevi usually are characterized by a benign clinical course, but few cases describing malignant changes with development of malignant melanoma have been reported.^9,10 Therefore, recognition of the clinical and histopathologic spectrum of agminated blue nevus is critical in order to avoid diagnostic pitfalls and confusion with melanoma.

The Diagnosis: Agminated Blue Nevus

Agminated blue nevus is a rare melanocytic nevus that characteristically presents as a group of multiple small, bluish papules occurring in a well-circumscribed area.¹ It also has been referred to as a plaque-type nevus^2,3 and an eruptive blue nevus.⁴ Originally described by Upshaw et al² in 1947, agminated blue nevi may be congenital or arise in early childhood and almost always occur on the trunk. The skin between the papules often is unaffected or sometimes may show bluish or brown pigmentation.⁴ Agminated blue nevi usually are smaller than 10 cm in diameter; however, rare cases have measured up to 24 cm.^1,4-6 The incidence of agminated blue nevi is 2 times higher in males than in females.¹

A biopsy of the lesion revealed pigmented dendritic melanocytes admixed with melanophages, forming fascicles and bundles (A)(H&E, original magnification ×10). In some areas the dermis was uninvolved. Higher magnification showed dendritic and epithelioid melanocytes extending down along the adnexal structures (B)(H&E, original magnification ×40).

Histopathologically, agminated blue nevi typically demonstrate the features of common and/or cellular blue nevi. Cytologic atypia and mitoses are rare.¹ The degree of cellularity and pigmentation of the lesions is variable, and the presence of subcutaneous cellular nodules also has been described.⁵

In our patient, histologic evaluation revealed foci of diffuse dermal spindle cell proliferation composed of heavily pigmented dendritic melanocytes admixed with melanophages in a fibrotic stroma (Figure, A). The dermis was uninvolved in some areas and the melanocytes were epithelioid and formed fascicles and bundles that extended down adnexal structures in other areas (Figure, B). Junctional involvement of melanocytes, cellular atypia, and mitoses were not identified. Our case demonstrated a combination of histologic findings of a cellular blue nevus as well as features reminiscent of a deep penetrating nevus. The differential diagnosis of agminated blue nevus includes agminated Spitz nevus arising in a speckled lentiginous nevus,⁷ dermal melanocytosis, melanoma, and pilar neurocristic hamartoma. Pilar neurocristic hamartomas may resemble plaque-type blue nevi; however, the former show a predilection for the scalp, histologically demonstrate features that overlap with blue nevi and congenital nevi, and are associated with neural structures that show Schwannian differentiation.⁸ Agminated blue nevi usually are characterized by a benign clinical course, but few cases describing malignant changes with development of malignant melanoma have been reported.^9,10 Therefore, recognition of the clinical and histopathologic spectrum of agminated blue nevus is critical in order to avoid diagnostic pitfalls and confusion with melanoma.

The Diagnosis: Agminated Blue Nevus

Agminated blue nevus is a rare melanocytic nevus that characteristically presents as a group of multiple small, bluish papules occurring in a well-circumscribed area.¹ It also has been referred to as a plaque-type nevus^2,3 and an eruptive blue nevus.⁴ Originally described by Upshaw et al² in 1947, agminated blue nevi may be congenital or arise in early childhood and almost always occur on the trunk. The skin between the papules often is unaffected or sometimes may show bluish or brown pigmentation.⁴ Agminated blue nevi usually are smaller than 10 cm in diameter; however, rare cases have measured up to 24 cm.^1,4-6 The incidence of agminated blue nevi is 2 times higher in males than in females.¹

A biopsy of the lesion revealed pigmented dendritic melanocytes admixed with melanophages, forming fascicles and bundles (A)(H&E, original magnification ×10). In some areas the dermis was uninvolved. Higher magnification showed dendritic and epithelioid melanocytes extending down along the adnexal structures (B)(H&E, original magnification ×40).

Histopathologically, agminated blue nevi typically demonstrate the features of common and/or cellular blue nevi. Cytologic atypia and mitoses are rare.¹ The degree of cellularity and pigmentation of the lesions is variable, and the presence of subcutaneous cellular nodules also has been described.⁵

In our patient, histologic evaluation revealed foci of diffuse dermal spindle cell proliferation composed of heavily pigmented dendritic melanocytes admixed with melanophages in a fibrotic stroma (Figure, A). The dermis was uninvolved in some areas and the melanocytes were epithelioid and formed fascicles and bundles that extended down adnexal structures in other areas (Figure, B). Junctional involvement of melanocytes, cellular atypia, and mitoses were not identified. Our case demonstrated a combination of histologic findings of a cellular blue nevus as well as features reminiscent of a deep penetrating nevus. The differential diagnosis of agminated blue nevus includes agminated Spitz nevus arising in a speckled lentiginous nevus,⁷ dermal melanocytosis, melanoma, and pilar neurocristic hamartoma. Pilar neurocristic hamartomas may resemble plaque-type blue nevi; however, the former show a predilection for the scalp, histologically demonstrate features that overlap with blue nevi and congenital nevi, and are associated with neural structures that show Schwannian differentiation.⁸ Agminated blue nevi usually are characterized by a benign clinical course, but few cases describing malignant changes with development of malignant melanoma have been reported.^9,10 Therefore, recognition of the clinical and histopathologic spectrum of agminated blue nevus is critical in order to avoid diagnostic pitfalls and confusion with melanoma.

The Diagnosis: Eccrine Poroma

A shave biopsy of the lesion was performed for definitive diagnosis and demonstrated a well-circumscribed tumor with cords and broad columns composed of uniform basaloid cells extending into the dermis and in areas connecting to the overlying epidermis (Figure). There also were small ducts and cysts admixed in the tumor columns that were embedded in a tumor stroma rich in blood vessels. A diagnosis of eccrine poroma was made based on these characteristic histologic features.

Biopsy revealed a basaloid tumor originating from the epidermis and extending into the dermis (A)(H&E, original magnification ×4). On higher magnification, ducts were evident amongst the tumor cells and a vascular rich stroma was revealed (B)(H&E, original magnification ×10).

First described by Pinkus et al¹ in 1956, eccrine poroma is a benign neoplasm of cells from the intraepidermal ductal portion of the eccrine sweat gland. Eccrine poroma (along with hidroacanthoma simplex, dermal duct tumor, and poroid hidradenoma) is one of the poroid neoplasms, which account for approximately 10% of all primary sweat gland tumors.² Eccrine poroma usually is seen in patients over 40 years of age without any predilection for race or sex.

Characteristically, eccrine poromas clinically manifest as solitary, firm, sharply demarcated papules or nodules that may be sessile or pedunculated and rarely exceed 2 cm in diameter. This entity classically presents on acral, non–hair-bearing areas (eg, palms and soles). Eccrine poromas have a wide range of clinical appearances that can lead to broad differential diagnoses³ and have been described as flesh-colored,³ pink to red,⁴ purple,⁵ and pigmented^3,4 papules or nodules depending on features such as blood vessel proliferation and pigment deposition.

Eccrine poromas also have been reported on hair-bearing areas of the body, including the head,³ neck,^3,6 chest,^4,6 hip,⁷ and pubic area,⁸ despite the paucity of eccrine glands in these areas on the body. These findings suggest that these neoplasms may not be purely eccrine in origin. The wide range of clinical presentations of eccrine poromas has prompted investigation into further classification and delineation of this neoplasm.³ The occurrence of eccrine poromas on areas of the skin known to have few eccrine glands suggests that eccrine poromas may not be purely comprised of eccrine ducts and instead may be of apocrine origin.^3,9,10 Histologic features of eccrine poromas that suggest apocrine origination include sebaceous and follicular differentiation (eg, folliculocentric distribution), the association with the follicular infundibulum, and the presence of follicular germ cells.^3,9,10 Thus, apocrine gland involvement in eccrine poromas may account for their appearance in anatomic areas that do not have high concentrations of eccrine glands, such as the trunk and pubic area.

Based on these findings, eccrine poromas may therefore be of eccrine and/or apocrine origin; however, the nomenclature of this neoplasm remains confusing and possibly misleading, as the term eccrine poroma continues to be accepted even in instances in which the differentiation appears to be largely apocrine. The terms poroma and eccrine poroma often are used interchangeably, which contributes to the confusion by failing to acknowledge the possibility of apocrine influence and possibly causing the clinician to exclude eccrine poromas from the differential diagnosis in areas that do not have high concentrations of eccrine glands.

Because of their high degree of clinical variability, characteristic acral location, and misleading nomenclature, eccrine poromas often are mistakenly confused with a long list of other cutaneous neoplasms, including hemangiomas, pyogenic granulomas, melanocytic nevi, warts, cysts, and other adnexal neoplasms.³ In our case, the lesion was abnormally large and was clinically concerning for an unusual sebaceous nevus. Its location on the lower back is not commonly noted and should remind the clinician of the possibility of apocrine differentiation. Clinicians should be aware of the wide phenotypic diversity of eccrine poromas, and therefore they should consider this diagnosis in their differential diagnosis for solitary papules or nodules occurring in any anatomic area.

The Diagnosis: Eccrine Poroma

A shave biopsy of the lesion was performed for definitive diagnosis and demonstrated a well-circumscribed tumor with cords and broad columns composed of uniform basaloid cells extending into the dermis and in areas connecting to the overlying epidermis (Figure). There also were small ducts and cysts admixed in the tumor columns that were embedded in a tumor stroma rich in blood vessels. A diagnosis of eccrine poroma was made based on these characteristic histologic features.

Biopsy revealed a basaloid tumor originating from the epidermis and extending into the dermis (A)(H&E, original magnification ×4). On higher magnification, ducts were evident amongst the tumor cells and a vascular rich stroma was revealed (B)(H&E, original magnification ×10).

First described by Pinkus et al¹ in 1956, eccrine poroma is a benign neoplasm of cells from the intraepidermal ductal portion of the eccrine sweat gland. Eccrine poroma (along with hidroacanthoma simplex, dermal duct tumor, and poroid hidradenoma) is one of the poroid neoplasms, which account for approximately 10% of all primary sweat gland tumors.² Eccrine poroma usually is seen in patients over 40 years of age without any predilection for race or sex.

Characteristically, eccrine poromas clinically manifest as solitary, firm, sharply demarcated papules or nodules that may be sessile or pedunculated and rarely exceed 2 cm in diameter. This entity classically presents on acral, non–hair-bearing areas (eg, palms and soles). Eccrine poromas have a wide range of clinical appearances that can lead to broad differential diagnoses³ and have been described as flesh-colored,³ pink to red,⁴ purple,⁵ and pigmented^3,4 papules or nodules depending on features such as blood vessel proliferation and pigment deposition.

Eccrine poromas also have been reported on hair-bearing areas of the body, including the head,³ neck,^3,6 chest,^4,6 hip,⁷ and pubic area,⁸ despite the paucity of eccrine glands in these areas on the body. These findings suggest that these neoplasms may not be purely eccrine in origin. The wide range of clinical presentations of eccrine poromas has prompted investigation into further classification and delineation of this neoplasm.³ The occurrence of eccrine poromas on areas of the skin known to have few eccrine glands suggests that eccrine poromas may not be purely comprised of eccrine ducts and instead may be of apocrine origin.^3,9,10 Histologic features of eccrine poromas that suggest apocrine origination include sebaceous and follicular differentiation (eg, folliculocentric distribution), the association with the follicular infundibulum, and the presence of follicular germ cells.^3,9,10 Thus, apocrine gland involvement in eccrine poromas may account for their appearance in anatomic areas that do not have high concentrations of eccrine glands, such as the trunk and pubic area.

Based on these findings, eccrine poromas may therefore be of eccrine and/or apocrine origin; however, the nomenclature of this neoplasm remains confusing and possibly misleading, as the term eccrine poroma continues to be accepted even in instances in which the differentiation appears to be largely apocrine. The terms poroma and eccrine poroma often are used interchangeably, which contributes to the confusion by failing to acknowledge the possibility of apocrine influence and possibly causing the clinician to exclude eccrine poromas from the differential diagnosis in areas that do not have high concentrations of eccrine glands.

Because of their high degree of clinical variability, characteristic acral location, and misleading nomenclature, eccrine poromas often are mistakenly confused with a long list of other cutaneous neoplasms, including hemangiomas, pyogenic granulomas, melanocytic nevi, warts, cysts, and other adnexal neoplasms.³ In our case, the lesion was abnormally large and was clinically concerning for an unusual sebaceous nevus. Its location on the lower back is not commonly noted and should remind the clinician of the possibility of apocrine differentiation. Clinicians should be aware of the wide phenotypic diversity of eccrine poromas, and therefore they should consider this diagnosis in their differential diagnosis for solitary papules or nodules occurring in any anatomic area.

The Diagnosis: Eccrine Poroma

A shave biopsy of the lesion was performed for definitive diagnosis and demonstrated a well-circumscribed tumor with cords and broad columns composed of uniform basaloid cells extending into the dermis and in areas connecting to the overlying epidermis (Figure). There also were small ducts and cysts admixed in the tumor columns that were embedded in a tumor stroma rich in blood vessels. A diagnosis of eccrine poroma was made based on these characteristic histologic features.

Biopsy revealed a basaloid tumor originating from the epidermis and extending into the dermis (A)(H&E, original magnification ×4). On higher magnification, ducts were evident amongst the tumor cells and a vascular rich stroma was revealed (B)(H&E, original magnification ×10).

First described by Pinkus et al¹ in 1956, eccrine poroma is a benign neoplasm of cells from the intraepidermal ductal portion of the eccrine sweat gland. Eccrine poroma (along with hidroacanthoma simplex, dermal duct tumor, and poroid hidradenoma) is one of the poroid neoplasms, which account for approximately 10% of all primary sweat gland tumors.² Eccrine poroma usually is seen in patients over 40 years of age without any predilection for race or sex.

Characteristically, eccrine poromas clinically manifest as solitary, firm, sharply demarcated papules or nodules that may be sessile or pedunculated and rarely exceed 2 cm in diameter. This entity classically presents on acral, non–hair-bearing areas (eg, palms and soles). Eccrine poromas have a wide range of clinical appearances that can lead to broad differential diagnoses³ and have been described as flesh-colored,³ pink to red,⁴ purple,⁵ and pigmented^3,4 papules or nodules depending on features such as blood vessel proliferation and pigment deposition.

Eccrine poromas also have been reported on hair-bearing areas of the body, including the head,³ neck,^3,6 chest,^4,6 hip,⁷ and pubic area,⁸ despite the paucity of eccrine glands in these areas on the body. These findings suggest that these neoplasms may not be purely eccrine in origin. The wide range of clinical presentations of eccrine poromas has prompted investigation into further classification and delineation of this neoplasm.³ The occurrence of eccrine poromas on areas of the skin known to have few eccrine glands suggests that eccrine poromas may not be purely comprised of eccrine ducts and instead may be of apocrine origin.^3,9,10 Histologic features of eccrine poromas that suggest apocrine origination include sebaceous and follicular differentiation (eg, folliculocentric distribution), the association with the follicular infundibulum, and the presence of follicular germ cells.^3,9,10 Thus, apocrine gland involvement in eccrine poromas may account for their appearance in anatomic areas that do not have high concentrations of eccrine glands, such as the trunk and pubic area.

Based on these findings, eccrine poromas may therefore be of eccrine and/or apocrine origin; however, the nomenclature of this neoplasm remains confusing and possibly misleading, as the term eccrine poroma continues to be accepted even in instances in which the differentiation appears to be largely apocrine. The terms poroma and eccrine poroma often are used interchangeably, which contributes to the confusion by failing to acknowledge the possibility of apocrine influence and possibly causing the clinician to exclude eccrine poromas from the differential diagnosis in areas that do not have high concentrations of eccrine glands.

Because of their high degree of clinical variability, characteristic acral location, and misleading nomenclature, eccrine poromas often are mistakenly confused with a long list of other cutaneous neoplasms, including hemangiomas, pyogenic granulomas, melanocytic nevi, warts, cysts, and other adnexal neoplasms.³ In our case, the lesion was abnormally large and was clinically concerning for an unusual sebaceous nevus. Its location on the lower back is not commonly noted and should remind the clinician of the possibility of apocrine differentiation. Clinicians should be aware of the wide phenotypic diversity of eccrine poromas, and therefore they should consider this diagnosis in their differential diagnosis for solitary papules or nodules occurring in any anatomic area.

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

The Diagnosis: Porokeratosis of Mibelli

There are 5 variants of porokeratosis: disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, porokeratosis of Mibelli, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis. The most common type is DSAP,¹ which is characterized by multiple lesions on the body, particularly in sun-exposed areas. The distinguishing feature of porokeratosis is the cornoid lamella, which is made up of parakeratotic cells extending through the stratum corneum. There also is a thin or absent granular layer beneath it (Figure).²

Patients generally present in the third and fourth decades of life.¹ Risk factors for porokeratosis include sun exposure, immunosuppression, and genetics.^2-4 Overexpression of the protein p53 in porokeratosis lesions has been demonstrated in studies investigating the genetics of porokeratosis.^5,6 A study of Chinese families with DSAP identified 3 different loci associated with DSAP: DSAP1, DSAP2, and DSAP3.² The progression to cancer has been noted in all types of porokeratosis lesions. Malignancies include squamous cell carcinoma, Bowen disease, and basal cell carcinoma.^7,8

Many treatments have been tried for DSAP including cryotherapy, topical 5-fluorouracil, photodynamic therapy, and topical imiquimod with varying success.¹ Our patient was treated with 
cryotherapy but had side effects from treatment including cellulitis and local infections with ulceration before finally healing.

Interestingly, our patient had a single lesion with pathology findings most consistent with DSAP at a later age. Although the pathology suggested DSAP, the size and solitary lesion was more consistent with porokeratosis of Mibelli. Porokeratosis of Mibelli can occur concurrently with DSAP,⁹ but we have not seen other lesions in this patient. We have educated our patient to be aware of other lesions that may occur in the future. Due to risk for malignant conversion, it is generally viewed as beneficial to treat patients who present with porokeratosis lesions. Our patient’s lesion ultimately cleared and he has not developed new lesions at 1-year follow-up.

Although DSAP generally presents in the third and fourth decades of life and porokeratosis of Mibelli during childhood, it is important to educate both dermatologists and primary care physicians to be aware of the possibility of both diagnoses in the elderly population.

The Diagnosis: Fixed Cutaneous Sporotrichosis

On further questioning at our dermatology clinic, the patient reported having landed face-first into rocks and gravel during the all-terrain vehicle accident. After his medical history was noted and a physical examination was completed, bacterial and fungal cultures of the wound were taken. The fungal culture was positive for Sporothrix schenckii. The patient was prescribed itraconazole 200 mg 3 times daily for 3 days, then 200 mg twice daily for an additional 4 weeks after the lesions completely resolved. An ophthalmologist was immediately consulted to rule out sinus and periorbital involvement. After computed tomography revealed possible preseptal cellulitis with frontal sinus involvement, the patient was admitted and intravenous amphotericin B was administered. Following consultations with infectious disease specialists and radiologists, amphotericin B was discontinued and the patient was discharged on itraconazole 200 mg twice daily with close monitoring. At 3-month follow-up, the sporotrichosis infection had completely cleared (Figure).

Deep fungal infections comprise 2 distinct groups: systemic and subcutaneous mycoses. Individuals with subcutaneous mycoses present with skin involvement as the primary feature. Sporotrichosis is the most common cause of this type of mycosis¹ and is caused by the dimorphic fungus S schenckii, an environmental saprophyte often residing in soil. Sporothrix schenckii exists as mold in a natural environment but exists as yeast in host tissue, thus causing ensuing infection.

Epidemiology

Sporotrichosis occurs worldwide but most frequently in temperate tropical and subtropical regions. The majority of cases are reported in Mexico and Central and South America¹; however, cases have been seen in the southern United States, Japan, and Australia.² In the United States, sporotrichosis is most commonly found in river valleys of the Midwest.

Sporothrix schenckii is most commonly isolated in hay, sphagnum moss, thorny plants, and soil, but it also has been described in other manifold host environments. Unusual origins of inoculation include an old and rust-stained camping tent in Mexico,³ crawl space joists of a house in Indiana,⁴ and hay bales used as props in a haunted house in Oklahoma.⁵

The incidence of infection is primarily sporadic; however, outbreaks among individuals who share a common environment favorable for the growth of S schenckii are at risk. Those identified to be at risk include rose gardeners, berry pickers, those who work in tree nurseries, horticulturists, landscapers, and miners.

Pathogenesis

As a dimorphic fungus, infection occurs when a conidium in the mold phase is introduced into the skin, usually by traumatic skin injury, and is 
converted to the yeast form in vivo. Distribution of infection by this organism is most commonly 
localized to the cutaneous, subcutaneous, and lymphocutaneous regions in healthy hosts but can involve visceral and osteoarticular structures in immunocompromised hosts.^1,6 Pulmonary and disseminated forms are rare but can occur when 
S schenckii conidia are inhaled. Zoonotic transmission of the fungus also can occur with exposure to infected animals. Sporothrix schenckii has been reported to occur in cats, dogs, horses, donkeys, squirrels, armadillos, and dolphins.^7-11

Pathology

Sporothrix schenckii is typically not visualized on microscopic examination due to the small number of microorganisms present; however, cultures grow rapidly 
(3–5 days) on Sabouraud agar. The fungus most commonly develops as white or off-white compact colonies that progressively darken with age, transitioning to gray and then black.¹ Microscopically, the hyphae produce oval or pyriform conidia, which are assembled 
in a typical bouquetlike manner. Conversion of the organism to yeast on enriched medium such as brain-heart infusion agar or blood-cysteine-glucose agar confirms the diagnosis.

Acute lesions typically show a nonspecific mixed infiltrate, but established lesions may reveal granulomatous formation and neutrophilic microabscesses.^1,2 Asteroid bodies, which are cigar-shaped yeasts surrounded by eosinophilic coronae radiata, may be found. Organisms are sparsely distributed within the lesions, necessitating a thorough examination of the culture for identification.

Clinical Features

Sporotrichosis has 3 main classifications: lymphocutaneous, fixed cutaneous, and disseminated. Lymphocutaneous sporotrichosis is the most common form of the infection.² The disease presents with a small indurated papule occurring approximately 7 to 30 days after inoculation into the skin. The papule slowly enlarges, forms a nodule, and then frequently ulcerates. Over time, draining lymphatics become edematous and inflammatory, and a chain of secondary nodules begins to appear proximal to the initial lesion. The primary and secondary nodules may continue to ulcerate; alternately, they may heal or become chronic.

In fixed cutaneous sporotrichosis, the infection remains localized to one region and a granuloma may develop, which also may ulcerate. Satellite nodules may appear along the periphery of the lesion. Lymphatic spread is not observed in this form of 
the disease.

The disseminated form is a result of hematogenous spread from the primary inoculation site and typically occurs in an immunocompromised host. This form can present as pulmonary disease, sinusitis, and meningitis.¹

Differential Diagnosis

The differential diagnosis for sporotrichosis includes atypical mycobacteria, nocardiosis, blastomycosis, pyogenic bacteria, leishmaniasis, tularemia, 
and tuberculosis.

Treatment

Treatment of sporotrichosis is always required. A saturated solution of potassium iodide has classically been used; however, it is frequently associated with side effects and can be problematic to administer.¹² Given its low cost and traditional efficacy, it may still be used in some parts of the world.

Currently, the treatment of choice for fixed cutaneous and lymphocutaneous sporotrichosis is itraconazole 100 to 200 mg once daily for 3 to 6 months.¹ The recommended treatment of osteoarticular sporotrichosis is itraconazole, but prolonged therapy is required.

Heat therapy is an alternative treatment option, as certain strains of S schenckii do not grow at temperatures higher than 35°C. Hot compresses must be used for at least 1 hour a day for several months, which may affect patient compliance.

Immunocompromised patients often have disseminated infection and require lifelong suppressive therapy with itraconazole and may require initial treatment with amphotericin B.¹³

Conclusion

Subcutaneous sporotrichosis can develop in patients with a traumatic injury involving vegetation, soil, or animals. Although some patients may develop more invasive disease, most infections in immunocompetent patients will resolve after 3 to 6 months of itraconazole 100 to 200 mg once daily.¹

The Diagnosis: Fixed Cutaneous Sporotrichosis

On further questioning at our dermatology clinic, the patient reported having landed face-first into rocks and gravel during the all-terrain vehicle accident. After his medical history was noted and a physical examination was completed, bacterial and fungal cultures of the wound were taken. The fungal culture was positive for Sporothrix schenckii. The patient was prescribed itraconazole 200 mg 3 times daily for 3 days, then 200 mg twice daily for an additional 4 weeks after the lesions completely resolved. An ophthalmologist was immediately consulted to rule out sinus and periorbital involvement. After computed tomography revealed possible preseptal cellulitis with frontal sinus involvement, the patient was admitted and intravenous amphotericin B was administered. Following consultations with infectious disease specialists and radiologists, amphotericin B was discontinued and the patient was discharged on itraconazole 200 mg twice daily with close monitoring. At 3-month follow-up, the sporotrichosis infection had completely cleared (Figure).

Deep fungal infections comprise 2 distinct groups: systemic and subcutaneous mycoses. Individuals with subcutaneous mycoses present with skin involvement as the primary feature. Sporotrichosis is the most common cause of this type of mycosis¹ and is caused by the dimorphic fungus S schenckii, an environmental saprophyte often residing in soil. Sporothrix schenckii exists as mold in a natural environment but exists as yeast in host tissue, thus causing ensuing infection.

Epidemiology

Sporotrichosis occurs worldwide but most frequently in temperate tropical and subtropical regions. The majority of cases are reported in Mexico and Central and South America¹; however, cases have been seen in the southern United States, Japan, and Australia.² In the United States, sporotrichosis is most commonly found in river valleys of the Midwest.

Sporothrix schenckii is most commonly isolated in hay, sphagnum moss, thorny plants, and soil, but it also has been described in other manifold host environments. Unusual origins of inoculation include an old and rust-stained camping tent in Mexico,³ crawl space joists of a house in Indiana,⁴ and hay bales used as props in a haunted house in Oklahoma.⁵

The incidence of infection is primarily sporadic; however, outbreaks among individuals who share a common environment favorable for the growth of S schenckii are at risk. Those identified to be at risk include rose gardeners, berry pickers, those who work in tree nurseries, horticulturists, landscapers, and miners.

Pathogenesis

As a dimorphic fungus, infection occurs when a conidium in the mold phase is introduced into the skin, usually by traumatic skin injury, and is 
converted to the yeast form in vivo. Distribution of infection by this organism is most commonly 
localized to the cutaneous, subcutaneous, and lymphocutaneous regions in healthy hosts but can involve visceral and osteoarticular structures in immunocompromised hosts.^1,6 Pulmonary and disseminated forms are rare but can occur when 
S schenckii conidia are inhaled. Zoonotic transmission of the fungus also can occur with exposure to infected animals. Sporothrix schenckii has been reported to occur in cats, dogs, horses, donkeys, squirrels, armadillos, and dolphins.^7-11

Pathology

Sporothrix schenckii is typically not visualized on microscopic examination due to the small number of microorganisms present; however, cultures grow rapidly 
(3–5 days) on Sabouraud agar. The fungus most commonly develops as white or off-white compact colonies that progressively darken with age, transitioning to gray and then black.¹ Microscopically, the hyphae produce oval or pyriform conidia, which are assembled 
in a typical bouquetlike manner. Conversion of the organism to yeast on enriched medium such as brain-heart infusion agar or blood-cysteine-glucose agar confirms the diagnosis.

Acute lesions typically show a nonspecific mixed infiltrate, but established lesions may reveal granulomatous formation and neutrophilic microabscesses.^1,2 Asteroid bodies, which are cigar-shaped yeasts surrounded by eosinophilic coronae radiata, may be found. Organisms are sparsely distributed within the lesions, necessitating a thorough examination of the culture for identification.

Clinical Features

Sporotrichosis has 3 main classifications: lymphocutaneous, fixed cutaneous, and disseminated. Lymphocutaneous sporotrichosis is the most common form of the infection.² The disease presents with a small indurated papule occurring approximately 7 to 30 days after inoculation into the skin. The papule slowly enlarges, forms a nodule, and then frequently ulcerates. Over time, draining lymphatics become edematous and inflammatory, and a chain of secondary nodules begins to appear proximal to the initial lesion. The primary and secondary nodules may continue to ulcerate; alternately, they may heal or become chronic.

In fixed cutaneous sporotrichosis, the infection remains localized to one region and a granuloma may develop, which also may ulcerate. Satellite nodules may appear along the periphery of the lesion. Lymphatic spread is not observed in this form of 
the disease.

The disseminated form is a result of hematogenous spread from the primary inoculation site and typically occurs in an immunocompromised host. This form can present as pulmonary disease, sinusitis, and meningitis.¹

Differential Diagnosis

The differential diagnosis for sporotrichosis includes atypical mycobacteria, nocardiosis, blastomycosis, pyogenic bacteria, leishmaniasis, tularemia, 
and tuberculosis.

Treatment

Treatment of sporotrichosis is always required. A saturated solution of potassium iodide has classically been used; however, it is frequently associated with side effects and can be problematic to administer.¹² Given its low cost and traditional efficacy, it may still be used in some parts of the world.

Currently, the treatment of choice for fixed cutaneous and lymphocutaneous sporotrichosis is itraconazole 100 to 200 mg once daily for 3 to 6 months.¹ The recommended treatment of osteoarticular sporotrichosis is itraconazole, but prolonged therapy is required.

Heat therapy is an alternative treatment option, as certain strains of S schenckii do not grow at temperatures higher than 35°C. Hot compresses must be used for at least 1 hour a day for several months, which may affect patient compliance.

Immunocompromised patients often have disseminated infection and require lifelong suppressive therapy with itraconazole and may require initial treatment with amphotericin B.¹³

Conclusion

Subcutaneous sporotrichosis can develop in patients with a traumatic injury involving vegetation, soil, or animals. Although some patients may develop more invasive disease, most infections in immunocompetent patients will resolve after 3 to 6 months of itraconazole 100 to 200 mg once daily.¹

The Diagnosis: Fixed Cutaneous Sporotrichosis

On further questioning at our dermatology clinic, the patient reported having landed face-first into rocks and gravel during the all-terrain vehicle accident. After his medical history was noted and a physical examination was completed, bacterial and fungal cultures of the wound were taken. The fungal culture was positive for Sporothrix schenckii. The patient was prescribed itraconazole 200 mg 3 times daily for 3 days, then 200 mg twice daily for an additional 4 weeks after the lesions completely resolved. An ophthalmologist was immediately consulted to rule out sinus and periorbital involvement. After computed tomography revealed possible preseptal cellulitis with frontal sinus involvement, the patient was admitted and intravenous amphotericin B was administered. Following consultations with infectious disease specialists and radiologists, amphotericin B was discontinued and the patient was discharged on itraconazole 200 mg twice daily with close monitoring. At 3-month follow-up, the sporotrichosis infection had completely cleared (Figure).

Deep fungal infections comprise 2 distinct groups: systemic and subcutaneous mycoses. Individuals with subcutaneous mycoses present with skin involvement as the primary feature. Sporotrichosis is the most common cause of this type of mycosis¹ and is caused by the dimorphic fungus S schenckii, an environmental saprophyte often residing in soil. Sporothrix schenckii exists as mold in a natural environment but exists as yeast in host tissue, thus causing ensuing infection.

Epidemiology

Sporotrichosis occurs worldwide but most frequently in temperate tropical and subtropical regions. The majority of cases are reported in Mexico and Central and South America¹; however, cases have been seen in the southern United States, Japan, and Australia.² In the United States, sporotrichosis is most commonly found in river valleys of the Midwest.

Sporothrix schenckii is most commonly isolated in hay, sphagnum moss, thorny plants, and soil, but it also has been described in other manifold host environments. Unusual origins of inoculation include an old and rust-stained camping tent in Mexico,³ crawl space joists of a house in Indiana,⁴ and hay bales used as props in a haunted house in Oklahoma.⁵

The incidence of infection is primarily sporadic; however, outbreaks among individuals who share a common environment favorable for the growth of S schenckii are at risk. Those identified to be at risk include rose gardeners, berry pickers, those who work in tree nurseries, horticulturists, landscapers, and miners.

Pathogenesis

As a dimorphic fungus, infection occurs when a conidium in the mold phase is introduced into the skin, usually by traumatic skin injury, and is 
converted to the yeast form in vivo. Distribution of infection by this organism is most commonly 
localized to the cutaneous, subcutaneous, and lymphocutaneous regions in healthy hosts but can involve visceral and osteoarticular structures in immunocompromised hosts.^1,6 Pulmonary and disseminated forms are rare but can occur when 
S schenckii conidia are inhaled. Zoonotic transmission of the fungus also can occur with exposure to infected animals. Sporothrix schenckii has been reported to occur in cats, dogs, horses, donkeys, squirrels, armadillos, and dolphins.^7-11

Pathology

Sporothrix schenckii is typically not visualized on microscopic examination due to the small number of microorganisms present; however, cultures grow rapidly 
(3–5 days) on Sabouraud agar. The fungus most commonly develops as white or off-white compact colonies that progressively darken with age, transitioning to gray and then black.¹ Microscopically, the hyphae produce oval or pyriform conidia, which are assembled 
in a typical bouquetlike manner. Conversion of the organism to yeast on enriched medium such as brain-heart infusion agar or blood-cysteine-glucose agar confirms the diagnosis.

Acute lesions typically show a nonspecific mixed infiltrate, but established lesions may reveal granulomatous formation and neutrophilic microabscesses.^1,2 Asteroid bodies, which are cigar-shaped yeasts surrounded by eosinophilic coronae radiata, may be found. Organisms are sparsely distributed within the lesions, necessitating a thorough examination of the culture for identification.

Clinical Features

Sporotrichosis has 3 main classifications: lymphocutaneous, fixed cutaneous, and disseminated. Lymphocutaneous sporotrichosis is the most common form of the infection.² The disease presents with a small indurated papule occurring approximately 7 to 30 days after inoculation into the skin. The papule slowly enlarges, forms a nodule, and then frequently ulcerates. Over time, draining lymphatics become edematous and inflammatory, and a chain of secondary nodules begins to appear proximal to the initial lesion. The primary and secondary nodules may continue to ulcerate; alternately, they may heal or become chronic.

In fixed cutaneous sporotrichosis, the infection remains localized to one region and a granuloma may develop, which also may ulcerate. Satellite nodules may appear along the periphery of the lesion. Lymphatic spread is not observed in this form of 
the disease.

The disseminated form is a result of hematogenous spread from the primary inoculation site and typically occurs in an immunocompromised host. This form can present as pulmonary disease, sinusitis, and meningitis.¹

Differential Diagnosis

The differential diagnosis for sporotrichosis includes atypical mycobacteria, nocardiosis, blastomycosis, pyogenic bacteria, leishmaniasis, tularemia, 
and tuberculosis.

Treatment

Treatment of sporotrichosis is always required. A saturated solution of potassium iodide has classically been used; however, it is frequently associated with side effects and can be problematic to administer.¹² Given its low cost and traditional efficacy, it may still be used in some parts of the world.

Currently, the treatment of choice for fixed cutaneous and lymphocutaneous sporotrichosis is itraconazole 100 to 200 mg once daily for 3 to 6 months.¹ The recommended treatment of osteoarticular sporotrichosis is itraconazole, but prolonged therapy is required.

Heat therapy is an alternative treatment option, as certain strains of S schenckii do not grow at temperatures higher than 35°C. Hot compresses must be used for at least 1 hour a day for several months, which may affect patient compliance.

Immunocompromised patients often have disseminated infection and require lifelong suppressive therapy with itraconazole and may require initial treatment with amphotericin B.¹³

Conclusion

Subcutaneous sporotrichosis can develop in patients with a traumatic injury involving vegetation, soil, or animals. Although some patients may develop more invasive disease, most infections in immunocompetent patients will resolve after 3 to 6 months of itraconazole 100 to 200 mg once daily.¹