[A woman with an unusual sonogram of the abdomen].

A 29-year-old female complained of abdominal swelling. Transvaginal sonography showed an unusual view of a cystic ovarian mass composed of various dense, round structures. A laparotomic right ovarian cystectomy was performed. The diagnosis was a mature teratoma or dermoid cyst, which is a benign germ cell tumor composed of differentiated, adult-type tissues.