[Idiopathic retroperitoneal fibrosis localizing in pelvic cavity: a case report].

We report a case of idiopathic retroperitoneal fibrosis localized in the pelvic cavity. A 54-year-old female was found to have a right hydronephrosis by abdominal ultrasonogram and was admitted to our department. Drip infusion pyelography (DIP) and computed tomography (CT) revealed a right hydroureteronephrosis and a right lower periureteral mass. The mass was confirmed to show low intensity on both T1 and T2 weighted image in magnetic resonance imaging (MRI), which suggested fibrous component. Various tumor marker values were within normal range. Tumor extirpation including lower ureter and ureterovesiconeostomy were performed after confirming pathologically the absence of malignancy by fresh frozen section during surgery. The tumor was diagnosed histologically as idiopathic retroperitoneal fibrosis. We briefly reviewed 223 cases of idiopathic retroperitoneal fibrosis in the Japanese literature.