[A case of idiopathic retroperitoneal fibrosis causing acute renal failure and markedly responsive to drug therapy].

We report a case of idiopathic retroperitoneal fibrosis in a 66-year-old man. He was admitted to our hospital because of acute renal failure, and emergent hemodialysis was performed. Computed tomography scanning showed a retroperitoneal mass surrounding the abdominal aorta and bilateral common iliac arteries. The mass involved bilateral ureters and acute renal failure was caused by bilateral hydronephrosis. Magnetic resonance imaging demonstrated that the mass was slightly high intensity on T2 weighted image. It was considered to be idiopathic retroperitoneal fibrosis. After inserting ureteral catheters into bilateral ureters, his renal function recovered. The layer of the fibrosis became thin by steroids and traditional Chinese medicine, and bilateral ureteral catheters could be removed two months later. At ten months after the treatment, no ureteral obstruction was observed and renal function is preserved.