[Idiopathic retroperitoneal fibrosis: report of 4 cases].

We report 4 cases of idiopathic retroperitoneal fibrosis (IRF). Two cases were demonstrated by surgical biopsy, and in one of them ureterolysis was performed at the same time. After pathological diagnosis, these two patients were treated by steroid therapy. The other two patients were suspected to have acute renal failure due to IRF, and they were treated by nephrostomy or by double-J ureteral stent. In one of them retroperitoneal fibrous tissue had almost disappeared on CT examination. None of these 4 patients have had recurrence of IRF.