Development of seven secondary neoplasms in a nevus sebaceous: a case report and literature review.

Nevus sebaceous of Jadassohn is a congenital cutaneous hamartoma with epidermal, sebaceous, follicular, and apocrine structures that usually appears at birth or in early childhood. It has the potential to generate a variety of secondary neoplasms of different lineages, and the risk increases with patient age. Although multiple neoplasms may occasionally arise within the same lesion, the coexistence of more than five secondary tumors is extremely rare. Here we report a case of seven secondary tumors including syringocystadenoma papilliferum, desmoplastic trichilemmoma, sebaceoma, trichoblastoma, pigmented trichoblastoma, sebaceous adenoma, and tumor of follicular infundibulum arising within a nevus sebaceous. The complete diagnosis relies on the histopathological analysis of multipoint biopsies and delicate pathological sections.