Eccrine Poroma Arising within a Nevus Sebaceus

Abstract

Background: Nevus Sebaceous (NS) is a congenital hamartoma characterized by orange to skin-colored verrucous plaques typically of the scalp, face, forehead, or neck. Numerous publications report cases of secondary neoplasms arising from NS plaques including trichoblastoma, syringocystadenoma papilliferum, and basal cell carcinoma. In some exceptional cases, poroma–adnexal tumors of the intraepidermal sweat gland duct–have been reported to arise in NS plaques. Case Presentation: A 56-year-old man presented to the dermatology clinic with a brown pedunculated verrucous plaque overlying scattered irregularly shaped dark-brown plaques. The pedunculated plaque was biopsied for histopathological evaluation and showed benign adnexal neoplasm with eccrine differentiation most consistent with a pigmented eccrine poroma. A wide-local excision for complete lesion removal and further histologic examination was performed. The second biopsy revealed focal areas of acanthosis and papillomatosis with sebaceous gland hyperplasia consistent with nevus sebaceous. Discussion: Upon literature review, there are seven documented cases of poroma growth within a NS, four of which are eccrine poromas. In comparing cases, clinical differences including distinct morphologies of NS and EP plaques, and coexisting neoplasms can be observed. To this degree, our case might offer insight into the unique and rare presentation of secondary EP plaques arising from primary NS lesions.