A case of median raphe cyst on the scrotum with atypical histologic features

Median raphe cyst is an uncommon condition occuring on the ventral median raphe from the glans penis to the anus and represents a defect in the embryologic development of the male genitalia. The cyst wall may derive from endoderm, ectoderm, or mucous glands which are a normal constitute of the male urethra. It is classified as either a dermoid cyst lined by stratified squamous epithelium of ectodermal origin or a mucous cyst lined by cuboidal or columnar epithelium of endodermal origin. Surgical excision is the treatment of choice. We report a case of an 11-year old boy with three median raphe cysts of the scrotum. The epithelial lining of the cysts was mainly composed of pseudostratified columnar cells with decapitation secretion and focally showed stratified squamous cells and a transitional zone of two types of cells. Immunohistochemically, pseudostratified columnar cells showed CK 7 and CK 13 positivity, but were negative for CK 20. Besides, stratified squamous cells were negative for CK 7, CK 13 and CK 20. We report a rare case of median raphe cyst that is a combined type of dermoid cyst and mucous cyst.