A Case of Mature Cystic Teratoma Covered with the Greater Omentum and Suspected Deriving from the Ovary

Abstract

A 62-year-old woman complaining of right lower abdominal pain was pointed out having an intraabdominal mass lesion by ultrasonography (US) examination at the home doctor's clinic and was referred to our hospital. There was previous history of undergoing left adnexectomy for mature cystic teratoma elsewhere 13 years earlier. Abdominal US examination revealed an oval shaped cystic lesion of 6 cm in diameter in the right lower quadrant of abdomen. Enhanced abdominal CT scan revealed that the oval-shaped cystic lesion with clear margin was composed of calcified capsular structure surrounded by-fat tissue with no infiltration into the adjacent organs, and a solid lesion was also found in this cystic lesion. MRI imaging demonstrated that the content of this cystic lesion mainly consisted of fat tissue. These findings were compatible with mature cystic teratoma. Thus, we diagnosed this lesion as mature cystic teratoma covered with the greater omentum clinically and performed surgical resection. Histopathology revealed that the cystic capsule was mainly composed of fibrous stromal structure with remarkable calcification with no epithelial spreads. This lesion did not include neoplastic growth nor atypical nuclear changes. The ovarian tissue components were seen in this cystic capsular structure. The hair and bone structures were also found in the solid lesion included in the cystic lesion. These findings suggested this lesion to be a cystic teratoma derived from the left ovary, which might be implanted into and covered with the greater omentum. Her postoperative course was uneventful, and she was discharged from our hospital on the fourth post-operative day.