Median raphe cyst of the penis: a report of two cases with immunohistochemical investigation.

Penile median raphe cysts are uncommon benign lesions occurring predominantly in the ventral aspect of the glans penis of young men. We observed two cases: those of a 67-year-old patient and a 22-year-old patient. The epithelial lining of the cysts was composed of pluristratified small cells that focally showed rows of columnar cells above the inner surface as well as a monolayered mucinous columnar epithelium. A columnar cell lining predominated in the younger patient. The cytokeratin (CK) immunostaining pattern of the two cysts (CK7(+++), CK13(+++), CK20(-), CAM 5.2(+)) supports the interpretation of a columnar mucinous epithelium undergoing immature urothelial metaplasia. Carcinoembryonic antigen immunostaining positivity of the columnar cells is probably related to the dysembryogenetic cloacal nature of the cysts. Neuroendocrine differentiation of sparse cells interspersed in the pluristratified epithelium was documented by immunohistochemical staining for chromogranin and synaptophysin. Cilia were not identified in the columnar cells by light microscopy or by antidynein immunohistochemistry.