The usefulness and limits of magnetic resonance imaging in the differential diagnosis of pelvic tumors

Three cases of benign pelvic tumors are presented (2 leiomyomas and 1 fibro ma). All three tumors were suspected of being malignant neoplasms because t hey were visualized as heterogeneous high signal intensity on T2-weighted i mages, and thus they were difficult to diagnose preoperatively. One of the leiomyomas was located in the retroperitoneum and had been misdiagnosed as an ovarian tumor. All three tumors exhibited secondary myxoid changes, thes e changes may have been responsible for the high signal intensity on the T2 -weighted MR images. Since benign tumors sometimes mimic malignant tumors o n MR images, exploratory laparotomy is essential to make a definitive diagn osis.