syringocystadenoma papilliferum
A benign adnexal neoplasm occurring during childhood or adolescence. It usually presents as a papular lesion or a plaque on the head and neck. It may arise in an organoid nevus such as sebaceous. It is characterized by an endophytic invagination of the epithelium into the dermis. There are dermal cystic spaces present, containing villous projections. Complete excision is curative.