Supernumerary ovary on sigmoid colon resembling an endometriotic lesion.

A 30-year-old woman with a history of endometriosis and chronic pelvic pain had right-sided pain and sonographic evaluation demonstrated a right ovarian cyst 5 cm in diameter. Laparotomy revealed a right ovarian cystic mass and the cystic mass was found on the sigmoid colon. After excision, histopathologic study revealed endometrioma for the ovarian cyst and a supernumerary ovary for the cystic mass on the sigmoid colon.