Dermoid cyst ; Fusion of ectoderm and endoderm ; Immunohistochemical study ; Median raphe cyst ; Mucous cyst
Abstract
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 pseudo-stratified 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.