M. Yadira Hurley, MD

To the Editor:

Chronic cutaneous lupus erythematosus (CCLE) is an inflammatory condition with myriad cutaneous manifestations. Most forms of CCLE have the potential to progress to systemic lupus erythematosus (SLE).¹

Blaschkolinear lupus erythematosus (BLE) is an exceedingly rare subtype of cutaneous lupus erythematosus that usually manifests during childhood as linear plaques along the lines of Blaschko.^2,3 Under normal conditions, Blaschko lines are not noticeable; they correspond to the direction of ectodermal cell migration during cutaneous embryogenesis.^4,5 The embryonic cells travel ventrolaterally, forming a V-shaped pattern on the back, an S-shaped pattern on the trunk, and an hourglass-shaped pattern on the face with several perpendicular intersections near the mouth and nose.⁶ During their migration, the cells are susceptible to somatic mutations and clonal expansion, resulting in a monoclonal population of genetically heterogenous cells. This phenomenon is known as somatic mosaicism and may lead to an increased susceptibility to an array of congenital and inflammatory dermatoses, such as cutaneous lupus erythematosus.⁴ Blaschkolinear entities tend to manifest in a unilateral distribution following exposure to a certain environmental trigger, such as trauma, viral illness, or UV radiation, although a trigger is not always present.⁷ We report a case of BLE manifesting on the head and neck in an adult patient.

A 46-year-old man presented with a pruritic rash of 3 months’ duration on the right cheek that extended inferiorly to the right upper chest. He had a medical history of well-controlled psoriasis, and he denied any antecedent trauma, fevers, chills, arthralgia, or night sweats. There had been no improvement with mometasone ointment 0.1% applied daily for 2 months as prescribed by his primary care provider. Physical examination revealed indurated, red-brown, atrophic plaques in a blaschkolinear distribution around the nose, right upper jaw, right side of the neck, and right upper chest (Figure, A).

To the Editor:

Chronic cutaneous lupus erythematosus (CCLE) is an inflammatory condition with myriad cutaneous manifestations. Most forms of CCLE have the potential to progress to systemic lupus erythematosus (SLE).¹

Blaschkolinear lupus erythematosus (BLE) is an exceedingly rare subtype of cutaneous lupus erythematosus that usually manifests during childhood as linear plaques along the lines of Blaschko.^2,3 Under normal conditions, Blaschko lines are not noticeable; they correspond to the direction of ectodermal cell migration during cutaneous embryogenesis.^4,5 The embryonic cells travel ventrolaterally, forming a V-shaped pattern on the back, an S-shaped pattern on the trunk, and an hourglass-shaped pattern on the face with several perpendicular intersections near the mouth and nose.⁶ During their migration, the cells are susceptible to somatic mutations and clonal expansion, resulting in a monoclonal population of genetically heterogenous cells. This phenomenon is known as somatic mosaicism and may lead to an increased susceptibility to an array of congenital and inflammatory dermatoses, such as cutaneous lupus erythematosus.⁴ Blaschkolinear entities tend to manifest in a unilateral distribution following exposure to a certain environmental trigger, such as trauma, viral illness, or UV radiation, although a trigger is not always present.⁷ We report a case of BLE manifesting on the head and neck in an adult patient.

A 46-year-old man presented with a pruritic rash of 3 months’ duration on the right cheek that extended inferiorly to the right upper chest. He had a medical history of well-controlled psoriasis, and he denied any antecedent trauma, fevers, chills, arthralgia, or night sweats. There had been no improvement with mometasone ointment 0.1% applied daily for 2 months as prescribed by his primary care provider. Physical examination revealed indurated, red-brown, atrophic plaques in a blaschkolinear distribution around the nose, right upper jaw, right side of the neck, and right upper chest (Figure, A).

To the Editor:

Chronic cutaneous lupus erythematosus (CCLE) is an inflammatory condition with myriad cutaneous manifestations. Most forms of CCLE have the potential to progress to systemic lupus erythematosus (SLE).¹

Blaschkolinear lupus erythematosus (BLE) is an exceedingly rare subtype of cutaneous lupus erythematosus that usually manifests during childhood as linear plaques along the lines of Blaschko.^2,3 Under normal conditions, Blaschko lines are not noticeable; they correspond to the direction of ectodermal cell migration during cutaneous embryogenesis.^4,5 The embryonic cells travel ventrolaterally, forming a V-shaped pattern on the back, an S-shaped pattern on the trunk, and an hourglass-shaped pattern on the face with several perpendicular intersections near the mouth and nose.⁶ During their migration, the cells are susceptible to somatic mutations and clonal expansion, resulting in a monoclonal population of genetically heterogenous cells. This phenomenon is known as somatic mosaicism and may lead to an increased susceptibility to an array of congenital and inflammatory dermatoses, such as cutaneous lupus erythematosus.⁴ Blaschkolinear entities tend to manifest in a unilateral distribution following exposure to a certain environmental trigger, such as trauma, viral illness, or UV radiation, although a trigger is not always present.⁷ We report a case of BLE manifesting on the head and neck in an adult patient.

A 46-year-old man presented with a pruritic rash of 3 months’ duration on the right cheek that extended inferiorly to the right upper chest. He had a medical history of well-controlled psoriasis, and he denied any antecedent trauma, fevers, chills, arthralgia, or night sweats. There had been no improvement with mometasone ointment 0.1% applied daily for 2 months as prescribed by his primary care provider. Physical examination revealed indurated, red-brown, atrophic plaques in a blaschkolinear distribution around the nose, right upper jaw, right side of the neck, and right upper chest (Figure, A).

The Diagnosis: Nodular Hidradenoma

A biopsy of the nodule showed a large, fungating, well-circumscribed, multilobulated neoplasm composed of primarily monotonous eosinophilic cells in a background of keloidal stroma (Figure). There was a minority population of small, monotonous, clear cells within the lobules, and no glandular structures were noted. Neither cytological nor architectural atypia were evident. MART-1/Melan-A and S-100 stains were negative, consistent with a diagnosis of benign nodular hidradenoma.

Nodular hidradenoma (also known as acrospiroma, solid-cystic hidradenoma, clear cell hidradenoma, and eccrine sweat gland adenoma) is a benign adnexal tumor of the apocrine or eccrine glands.^1,2 Nodular hidradenoma can arise at any cutaneous site but most commonly arises on the head and anterior portion of the trunk and rarely on the extremities.² It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter.^2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years.^2,4 There can be associated skin changes, including smoothening, thickening, ulceration, and bluish discoloration. Dermoscopy commonly shows a pinkish homogenous area that extends throughout the entire lesion. This homogenous area less commonly can be bluish, brownish, or pink-blue. Most nodular hidradenomas also can exhibit vascularization, with arborizing telangiectases, polymorphous atypical vessels, and linear irregular vessels being most common; however, this is not specific to nodular hidradenoma.3 Occasionally, tumors can drain serous or hemorrhagic fluid. Nodular hidradenoma commonly is a slow-growing tumor.⁵ Rapid increase in tumor size can be indicative of malignant transformation, hemorrhage into the tumor, or trauma to the area.²

Histologically, nodular hidradenoma consists of a circumscribed, nonencapsulated, multilobular tumor commonly found in the dermis and sometimes extending into the subcutaneous tissue. There usually is no epidermal attachment, and the overlying epidermis largely is normal. The tumor consists of large multilobulated areas of epithelial cells, tubular lamina, and large cystic areas filled with homogenous eosinophilic material.¹ It notably is composed of 2 epithelial cell types: (1) fusiform cells with elongated vesicular nuclei and basophilic cytoplasm, and (2) large polygonal cells with round eccentric nuclei and eosinophilic, periodic acid–Schiff–positive cytoplasm that washes away during fixation, giving the appearance of clear cells.⁵ Both types of cells are small, monotonous, and void of mitosis or dyskeratosis. Although there can be ducts with apocrine secretion present within the lobulated tumor, they are not consistently found. Due to the varying features that are neither mandatory nor consistent to arrive at this diagnosis, some dermatopathologists view the term hidradenoma as a catch-all term that includes several different types of benign sweat gland tumors. Some authors divide the terminology into apocrine hidradenoma and eccrine hidradenoma based on whether the tumor is composed of solely clear mucinous cells, or poroid and cuticular cells, respectively.

Although nodular hidradenoma classically is a benign tumor, total surgical excision is recommended due to the rare risk for malignant transformation. Rarely, longstanding hidradenomas can metastasize to lymph nodes, bone, or viscera; in these instances, metastatic hidradenoma has a 5-year survival rate of 30%. Recurrence may occur in tumors that are inadequately excised, and the rate of recurrence is estimated to be approximately 10% of surgically excised tumors.⁵ However, utilization of Mohs micrographic surgery for excision of nodular hidradenoma is associated with a reduced recurrence rate.⁶

Keloids present as painful, sometimes pruritic, raised scars that extend beyond the boundary of the initial injury, commonly arising on the shoulder, upper arm, and chest. Histopathology reveals nodules of thick hyalinized collagen bundles, keloidal collagen with mucinous ground substance, and few fibroblasts.⁷

Metastatic renal cell carcinoma to the skin most commonly presents on the face and scalp as a nodular, rapidly growing, round to oval lesion that is flesh colored to reddish purple in a patient with history of renal cell carcinoma.⁸ Histopathology shows clusters of atypical, nucleated clear cells surrounded by chicken wire vasculature.^8,9

Verruca vulgaris is caused by human papillomavirus and most commonly occurs on the hands and feet. It presents as a pink to white, sessile lesion with a verrucous surface and exophytic growths. Histopathology shows acanthosis; hypergranulosis; exophytic projections with a fibrovascular core; inward cupping of the rete ridges; and koilocytes, which are cells with an eccentric, raisinlike nucleus and vacuolated cytoplasm in the granular layer of the epidermis.¹⁰

Similar to nodular hidradenoma, nodular melanoma most commonly presents on the head and neck as a symmetric, elevated, amelanotic nodule, but in contrast to nodular hidradenoma, it typically is confined to a smaller diameter.¹¹ Histologically, it is characterized by sheets of atypical, commonly epithelioid melanocytes with a lack of maturation and brisk mitotic activity extending through the epidermis and dermis with lateral extension limited to less than 3 rete ridges.¹²

The Diagnosis: Nodular Hidradenoma

A biopsy of the nodule showed a large, fungating, well-circumscribed, multilobulated neoplasm composed of primarily monotonous eosinophilic cells in a background of keloidal stroma (Figure). There was a minority population of small, monotonous, clear cells within the lobules, and no glandular structures were noted. Neither cytological nor architectural atypia were evident. MART-1/Melan-A and S-100 stains were negative, consistent with a diagnosis of benign nodular hidradenoma.

Nodular hidradenoma (also known as acrospiroma, solid-cystic hidradenoma, clear cell hidradenoma, and eccrine sweat gland adenoma) is a benign adnexal tumor of the apocrine or eccrine glands.^1,2 Nodular hidradenoma can arise at any cutaneous site but most commonly arises on the head and anterior portion of the trunk and rarely on the extremities.² It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter.^2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years.^2,4 There can be associated skin changes, including smoothening, thickening, ulceration, and bluish discoloration. Dermoscopy commonly shows a pinkish homogenous area that extends throughout the entire lesion. This homogenous area less commonly can be bluish, brownish, or pink-blue. Most nodular hidradenomas also can exhibit vascularization, with arborizing telangiectases, polymorphous atypical vessels, and linear irregular vessels being most common; however, this is not specific to nodular hidradenoma.3 Occasionally, tumors can drain serous or hemorrhagic fluid. Nodular hidradenoma commonly is a slow-growing tumor.⁵ Rapid increase in tumor size can be indicative of malignant transformation, hemorrhage into the tumor, or trauma to the area.²

Histologically, nodular hidradenoma consists of a circumscribed, nonencapsulated, multilobular tumor commonly found in the dermis and sometimes extending into the subcutaneous tissue. There usually is no epidermal attachment, and the overlying epidermis largely is normal. The tumor consists of large multilobulated areas of epithelial cells, tubular lamina, and large cystic areas filled with homogenous eosinophilic material.¹ It notably is composed of 2 epithelial cell types: (1) fusiform cells with elongated vesicular nuclei and basophilic cytoplasm, and (2) large polygonal cells with round eccentric nuclei and eosinophilic, periodic acid–Schiff–positive cytoplasm that washes away during fixation, giving the appearance of clear cells.⁵ Both types of cells are small, monotonous, and void of mitosis or dyskeratosis. Although there can be ducts with apocrine secretion present within the lobulated tumor, they are not consistently found. Due to the varying features that are neither mandatory nor consistent to arrive at this diagnosis, some dermatopathologists view the term hidradenoma as a catch-all term that includes several different types of benign sweat gland tumors. Some authors divide the terminology into apocrine hidradenoma and eccrine hidradenoma based on whether the tumor is composed of solely clear mucinous cells, or poroid and cuticular cells, respectively.

Although nodular hidradenoma classically is a benign tumor, total surgical excision is recommended due to the rare risk for malignant transformation. Rarely, longstanding hidradenomas can metastasize to lymph nodes, bone, or viscera; in these instances, metastatic hidradenoma has a 5-year survival rate of 30%. Recurrence may occur in tumors that are inadequately excised, and the rate of recurrence is estimated to be approximately 10% of surgically excised tumors.⁵ However, utilization of Mohs micrographic surgery for excision of nodular hidradenoma is associated with a reduced recurrence rate.⁶

Keloids present as painful, sometimes pruritic, raised scars that extend beyond the boundary of the initial injury, commonly arising on the shoulder, upper arm, and chest. Histopathology reveals nodules of thick hyalinized collagen bundles, keloidal collagen with mucinous ground substance, and few fibroblasts.⁷

Metastatic renal cell carcinoma to the skin most commonly presents on the face and scalp as a nodular, rapidly growing, round to oval lesion that is flesh colored to reddish purple in a patient with history of renal cell carcinoma.⁸ Histopathology shows clusters of atypical, nucleated clear cells surrounded by chicken wire vasculature.^8,9

Verruca vulgaris is caused by human papillomavirus and most commonly occurs on the hands and feet. It presents as a pink to white, sessile lesion with a verrucous surface and exophytic growths. Histopathology shows acanthosis; hypergranulosis; exophytic projections with a fibrovascular core; inward cupping of the rete ridges; and koilocytes, which are cells with an eccentric, raisinlike nucleus and vacuolated cytoplasm in the granular layer of the epidermis.¹⁰

Similar to nodular hidradenoma, nodular melanoma most commonly presents on the head and neck as a symmetric, elevated, amelanotic nodule, but in contrast to nodular hidradenoma, it typically is confined to a smaller diameter.¹¹ Histologically, it is characterized by sheets of atypical, commonly epithelioid melanocytes with a lack of maturation and brisk mitotic activity extending through the epidermis and dermis with lateral extension limited to less than 3 rete ridges.¹²

The Diagnosis: Nodular Hidradenoma

A biopsy of the nodule showed a large, fungating, well-circumscribed, multilobulated neoplasm composed of primarily monotonous eosinophilic cells in a background of keloidal stroma (Figure). There was a minority population of small, monotonous, clear cells within the lobules, and no glandular structures were noted. Neither cytological nor architectural atypia were evident. MART-1/Melan-A and S-100 stains were negative, consistent with a diagnosis of benign nodular hidradenoma.

Nodular hidradenoma (also known as acrospiroma, solid-cystic hidradenoma, clear cell hidradenoma, and eccrine sweat gland adenoma) is a benign adnexal tumor of the apocrine or eccrine glands.^1,2 Nodular hidradenoma can arise at any cutaneous site but most commonly arises on the head and anterior portion of the trunk and rarely on the extremities.² It presents as a solitary nodular, cystic, or pedunculated mass that can reach up to several centimeters in diameter.^2,3 Nodular hidradenoma more commonly affects women compared to men with a ratio of 1.7 to 1 and commonly presents between the third and fifth decades of life, with an average age at presentation of 37.2 years.^2,4 There can be associated skin changes, including smoothening, thickening, ulceration, and bluish discoloration. Dermoscopy commonly shows a pinkish homogenous area that extends throughout the entire lesion. This homogenous area less commonly can be bluish, brownish, or pink-blue. Most nodular hidradenomas also can exhibit vascularization, with arborizing telangiectases, polymorphous atypical vessels, and linear irregular vessels being most common; however, this is not specific to nodular hidradenoma.3 Occasionally, tumors can drain serous or hemorrhagic fluid. Nodular hidradenoma commonly is a slow-growing tumor.⁵ Rapid increase in tumor size can be indicative of malignant transformation, hemorrhage into the tumor, or trauma to the area.²

Histologically, nodular hidradenoma consists of a circumscribed, nonencapsulated, multilobular tumor commonly found in the dermis and sometimes extending into the subcutaneous tissue. There usually is no epidermal attachment, and the overlying epidermis largely is normal. The tumor consists of large multilobulated areas of epithelial cells, tubular lamina, and large cystic areas filled with homogenous eosinophilic material.¹ It notably is composed of 2 epithelial cell types: (1) fusiform cells with elongated vesicular nuclei and basophilic cytoplasm, and (2) large polygonal cells with round eccentric nuclei and eosinophilic, periodic acid–Schiff–positive cytoplasm that washes away during fixation, giving the appearance of clear cells.⁵ Both types of cells are small, monotonous, and void of mitosis or dyskeratosis. Although there can be ducts with apocrine secretion present within the lobulated tumor, they are not consistently found. Due to the varying features that are neither mandatory nor consistent to arrive at this diagnosis, some dermatopathologists view the term hidradenoma as a catch-all term that includes several different types of benign sweat gland tumors. Some authors divide the terminology into apocrine hidradenoma and eccrine hidradenoma based on whether the tumor is composed of solely clear mucinous cells, or poroid and cuticular cells, respectively.

Although nodular hidradenoma classically is a benign tumor, total surgical excision is recommended due to the rare risk for malignant transformation. Rarely, longstanding hidradenomas can metastasize to lymph nodes, bone, or viscera; in these instances, metastatic hidradenoma has a 5-year survival rate of 30%. Recurrence may occur in tumors that are inadequately excised, and the rate of recurrence is estimated to be approximately 10% of surgically excised tumors.⁵ However, utilization of Mohs micrographic surgery for excision of nodular hidradenoma is associated with a reduced recurrence rate.⁶

Keloids present as painful, sometimes pruritic, raised scars that extend beyond the boundary of the initial injury, commonly arising on the shoulder, upper arm, and chest. Histopathology reveals nodules of thick hyalinized collagen bundles, keloidal collagen with mucinous ground substance, and few fibroblasts.⁷

Metastatic renal cell carcinoma to the skin most commonly presents on the face and scalp as a nodular, rapidly growing, round to oval lesion that is flesh colored to reddish purple in a patient with history of renal cell carcinoma.⁸ Histopathology shows clusters of atypical, nucleated clear cells surrounded by chicken wire vasculature.^8,9

Verruca vulgaris is caused by human papillomavirus and most commonly occurs on the hands and feet. It presents as a pink to white, sessile lesion with a verrucous surface and exophytic growths. Histopathology shows acanthosis; hypergranulosis; exophytic projections with a fibrovascular core; inward cupping of the rete ridges; and koilocytes, which are cells with an eccentric, raisinlike nucleus and vacuolated cytoplasm in the granular layer of the epidermis.¹⁰

Similar to nodular hidradenoma, nodular melanoma most commonly presents on the head and neck as a symmetric, elevated, amelanotic nodule, but in contrast to nodular hidradenoma, it typically is confined to a smaller diameter.¹¹ Histologically, it is characterized by sheets of atypical, commonly epithelioid melanocytes with a lack of maturation and brisk mitotic activity extending through the epidermis and dermis with lateral extension limited to less than 3 rete ridges.¹²

To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

Granular parakeratosis is a rare condition with an unclear etiology that results from a myriad of factors, including exposure to irritants, friction, moisture, and heat. The diagnosis is made based on a distinct histologic reaction pattern that may be protective against the triggers. We present a case of isolated scrotal granular parakeratosis in a patient with compensatory hyperhidrosis after endoscopic thoracic sympathectomy.

A 52-year-old man presented with a 5-year history of a recurrent rash affecting the scrotum. He experienced monthly flares that were exacerbated by inguinal hyperhidrosis. His symptoms included a burning sensation and pruritus followed by superficial desquamation, with gradual yet temporary improvement. His medical history was remarkable for primary axillary and palmoplantar hyperhidrosis, with compensatory inguinal hyperhidrosis after endoscopic thoracic sympathectomy 8 years prior to presentation.

Physical examination revealed a well-demarcated, scaly, erythematous plaque affecting the scrotal skin with sparing of the median raphe, penis, and inguinal folds (Figure 1). There were no other lesions noted in the axillary region or other skin folds.

Murine models have postulated that granular parakeratosis may result from a deficiency in caspase 14, a protease vital to the formation of a well-functioning skin barrier.⁹ A cornified envelope often is noted in granular parakeratotic cells with no defects in desmosomes and cell membranes, suggesting that the pathogenesis lies within processing of profilaggrin to filaggrin, resulting in a failure to degrade keratohyalin granules and aggregation of keratin filaments.¹⁰ Granular parakeratosis is not known to be associated with other medical conditions, but it has been observed in patients receiving chemotherapy for breast¹¹ and ovarian¹² carcinomas. In infants with atopic dermatitis, granular parakeratosis was reported in 5 out of 7 cases.⁶ In our patient with secondary inguinal hyperhidrosis after thoracic sympathectomy, granular parakeratosis may be reactive to excess sweating and friction in the scrotal area.

Granular parakeratosis follows a waxing and waning pattern that may spontaneously resolve without any treatment; it also can follow a protracted course, as in a case with associated facial papules that persisted for 20 years.¹³ Topical corticosteroids alone or in combination with topical antifungal agents have been used for the treatment of granular parakeratosis with the goal of accelerating resolution.^2,14 However, the efficacy of these therapeutic interventions is limited, and no controlled trials are underway. Topical vitamin D analogues^15,16 and topical retinoids¹⁷ also have been reported with successful outcomes. Spontaneous resolution also has been observed in 2 different cases after previously being unresponsive to topical treatment.^18,19 Treatment with Clostridium botulinum toxin A resulted in complete remission of the disease observed at 6-month follow-up. The pharmacologic action of the neurotoxin disrupts the stimulation of eccrine sweat glands, resulting in decreased sweating, a known exacerbating factor of granular parakeratosis.²⁰

In summary, our case represents a unique clinical presentation of granular parakeratosis with classic histopathologic features. A high index of suspicion and a biopsy are vital to arriving at the correct diagnosis.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.

To the Editor:

A 34-year-old woman presented for evaluation of dry mouth and painless peeling of the oral mucosa of 2 months’ duration. She denied any other skin eruptions, dry eyes, vulvar or vaginal pain, or recent hair loss. A recent antinuclear antibodies test was negative. The patient’s medical history was otherwise unremarkable and her current medications included multivitamins only.

Oral examination revealed peeling gray-white tissue on the buccal mucosa and mouth floor (Figure 1). After the tissue was manually removed with a tongue blade, the mucosal base was normal in color and texture. The patient denied bruxism, biting of the mucosa or other oral trauma, or use of tobacco or nonsteroidal anti-inflammatory drugs.

Biopsies from the buccal mucosa were performed to rule out erosive lichen planus and autoimmune blistering disorders. Microscopy revealed parakeratosis and intracellular edema of the mucosa. An intraepithelial cleft at the parakeratotic surface also was present (Figure 2). Minimal inflammation was noted. Fungal staining and direct immunofluorescence were negative.

The gray-white clinical appearance of the oral mucosa resembled leukoedema, but the peeling phenomenon was uncharacteristic. Histologically, leukoedema typically has a parakeratotic and acanthotic epithelium with marked intracellular edema of the spinous layer.^1,2 Our patient demonstrated intracellular edema with the additional finding of a superficial intraepithelial cleft. These features were consistent with the observed mucosal sloughing and normal tissue base and led to our diagnosis of leukoedema with mucosal desquamation. This clinical and histologic picture was previously described in another report, but a causative agent could not be identified.²

Because leukoedema can be secondary to chemical or mechanical trauma,³ we hypothesized that the patient’s toothpaste may be the causative agent. After discontinuing use of her regular toothpaste and keeping the rest of her oral hygiene routine unchanged, the patient’s condition resolved within 2 days. The patient could not identify how long she had been using the toothpaste before symptoms began.

Our case as well as a report in the literature suggest that leukoedema with mucosal desquamation may be the result of contact mucositis to dental hygiene products.³ Reports in the dental literature suggest that a possible cause for oral mucosal desquamation is sensitivity to sodium lauryl sulfate (SLS),^1,4 an ingredient used in some toothpastes, including the one used by our patient. The patient has since switched to a non–SLS-containing toothpaste and has remained asymptomatic. She was unwilling to reintroduce an SLS-containing product for further evaluation.

Sodium lauryl sulfate is a strong anionic detergent that is commonly used as a foaming agent in dentifrices.⁴ In products with higher concentrations of SLS, the incidence of oral epithelial desquamation increases. Triclosan has been shown to protect against this irritant phenomenon.⁵ Interestingly, the SLS-containing toothpaste used by our patient did not contain triclosan.

Although leukoedema and mucosal desquamation induced by oral care products are well-described in the dental literature, it is important for dermatologists to be aware of this phenomenon, as the differential diagnosis includes autoimmune blistering disorders and erosive lichen planus, for which dermatology referral may be requested. Further studies of SLS and other toothpaste ingredients are needed to establish if sloughing of the oral mucosa is primarily caused by SLS or another ingredient.