Basal Cell Carcinoma Arising from an Epidermal Nevus: A Case Report and Review of the Literature.

An epidermal nevus is known to appear at birth or in early childhood. Generally, it does not undergo major changes throughout life and can be left untreated. We report a case of basal cell carcinoma arising from an epidermal nevus in a 79-year-old man with congenital linear brown epidermodysplasia and nodular lesions on the right posterior neck. He had no other symptoms that could be attributed to epidermal nevus syndrome. He reported leakage of exudate from the nodule in recent years. Upon resection, the histopathological examination revealed an eccrine sweat gland tumor and basal cell carcinoma in a portion of the epidermal nevus. Cases of malignant tumors (e.g., squamous cell carcinoma and basal cell carcinoma) arising from an epidermal nevus have been reported previously. Nevertheless, preventive resection is not recommended in all cases. Epidermal nevi, even those left untreated or with changed properties, are rarely malignant.