Primary Cutaneous Apocrine Carcinoma and Basal Cell Carcinoma Arising in a Nevus Sebaceous of Jadassohn: Case Report and Literature Review.

Nevus sebaceous of Jadassohn (NSJ) is a congenital organoid hamartoma composed of epidermal, follicular, sebaceous, and apocrine elements that may give rise to secondary neoplasms later in life. Although most tumors arising in NSJ are benign adnexal proliferations, malignant neoplasms may occasionally develop. We report a case of a 56-year-old female patient with a long-standing lesion on the parietal scalp. Histopathologic examination revealed NSJ associated with 2 distinct malignant neoplasms: primary cutaneous apocrine carcinoma and superficial basal cell carcinoma. The diagnosis of apocrine carcinoma was established based on the morphologic findings and clinicoradiologic evaluation to exclude an internal primary malignancy. This case highlights the pluripotential nature of nevus sebaceous and underscores the importance of careful histopathologic evaluation of long-standing lesions that develop a new nodular component. This is particularly important as multiple and even malignant neoplasms may arise within a single lesion.