Mature Cystic Teratoma in Douglas' Pouch

Mature cystic teratoma is one of the most common ovarian neoplasms, but extragonadal teratoma is rare. Teratoma in Douglas' pouch is extremely rare, and only 12 cases have been reported since the first case was described in 1978. We report a 20-year-old woman with a multicystic mass in Douglas' pouch that was treated via laparoscopic resection. The tumor consisted of cysts lined by stratified squamous epithelium with an accumulation of keratin debris and various mature tissues. No immature elements or malignancy was found in the tumor, confirming the pathologic diagnosis of a mature cystic teratoma. The teratoma contained no ovarian tissues and both of the ovaries were intact on laparoscopy. These findings suggest that the teratoma originated primarily in Douglas' pouch rather than being caused by autoamputation of a previously existing ovarian teratoma. This is the first case that simultaneously showed normal ovaries and a teratoma in Douglas' pouch on laparoscopy.