Accessory scrotum or perineal collision-hamartoma. A case report to illustrate a misnomer.

A case of a congenital perineal tumor in a male infant is described, which consisted of separated fat and smooth muscle tissue in nodular arrangement. According to its clinical presentation, this lesion would be grouped into the category of so called "accessory scrotum," as part of the entity of ectopic scrotum. Based on our case and on a review of the literature, the possibility is raised that this labelling may be inappropriate on grounds of etiology and pathomorphology. It is suggested to consider similar lesions as the result of a perineal hamartomatous fat tissue overgrowth with transposed scrotal skin, which may or may not show additional hamartomatous proliferation of smooth muscle bundles, and to label them "perineal lipoma/lipoblastoma with ectopic scrotal skin" or "perineal collision-hamartoma" in the case of a prominent isolated smooth muscle component.