A unexpected growth arising within nevus sebaceous of Jadassohn

The predisposition to epithelial neoplasms in nevus sebaceous is well established; most tumors occur in adults and are benign. Hidradenoma is a relatively rare benign tumor of sweat gland origin that can rarely arise within a nevus sebaceous. We present an interesting case of a hidradenoma and sebaceoma arising within a nevus sebaceous and present a literature review of the 2 conditions. Even though hidradenoma is a benign tumor, we would advocate complete excision given the potential for malignant transformation.