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Case ReportsAbstract
We describe a 2-week-old male with a firm, hyperpigmented nodule on his left lower extremity that was present since birth. Histology of the lesion demonstrated a proliferation of eccrine glands with ductal hyperplasia and surrounding stromal mucin in addition to acanthosis and hyperkeratosis of the overlying epidermis. The diagnosis of mucinous eccrine nevus (MEN) was made. There are only fifteen reported cases in the English literature to date. MEN is an extremely rare, benign entity. It does not regress spontaneously. Most cases have an age of onset prior to puberty and present clinically with a solitary, unilateral lesion that is either brown-red, erythematous, or hyperpigmented which can be accompanied by localized hyperhidrosis. There has been a blaschkoid variant of MEN described. Diagnosis is typically made through biopsy. On histopathology, there is a proliferation of eccrine glands forming a dermal papule with overlying hyperkeratosis and acanthosis of the epidermis. Positive alcian blue staining can confirm the deposition of mucin within the stroma surrounding the eccrine glands to support the diagnosis of a mucinous variant of eccrine nevus. An additional variant is angiomyxoid eccrine nevus which has similar features to MEN with the addition of numerous capillary vessels associated with myxoid stroma. The clinical differential diagnoses include subcutaneous granuloma annulare, fat necrosis, juvenile xanthogranuloma, connective-tissue nevus, angiolymphoid hyperplasia with eosinophilia, and eccrine angiomatous hamartoma. Treatment typically consists of observation or surgical excision.