Retrorectal epidermoid cyst with unusually elevated serum SCC level, initially diagnosed as an ovarian tumor.

Retrorectal epidermoid cyst is one of the developmental cysts which arise from remnants of embryonic tissues. We report a rare case of retrorectal epidermoid cyst, initially diagnosed as an ovarian tumor. Serum SCC value as tumor marker was elevated to the high level. Laparoscopy revealed ovaries, uterus and other pelvic organs were all normal. This tumor existed in the retroperitoneal cavity and compressed the rectum. Later, complete tumor resection was performed by laparotomy. Histological study revealed the epithelium of this tumor consisted of only squamous cells without atypia, and the diagnosis of this tumor was retrorectal epidermoid cyst. Retrorectal epidermoid cyst is very rare, and difficult to diagnose before surgery. However, if we have-knowledge of developmental cysts, and by careful digital examination and image diagnosis, a differential diagnosis can be made.