[Retroperitoneal fibrosis].

A 53-year-old man without previous significant illness developed severe backache. Neither physiotherapy nor nonsteroidal anti-inflammatory drugs improved his condition so that he had been regularly taking pain-killing medication. 6 months later elevated retention values were detected and the patient was admitted to hospital. On admission the erythrocyte sedimentation rate (ESR) was markedly elevated in the presence of a normocytic anaemia, serum creatinine concentration of 3.71 mg/dl (blood urea of 112 mg/dl) and haematuria. Sonography demonstrated bilateral hydronephrosis, stage III, and a weekly echogenic para-aortic mass. Abdominal computed tomography showed a half-moon-shaped density anterior to the aorta. The middle segments of both ureters were displaced medially and the proximal parts dilated. Other causes (tumour, drug therapy, inflammation) having been largely excluded, idiopathic retroperitoneal fibrosis was diagnosed. The marked urinary obstruction necessitated the implantation of double-J-stents. Immunosuppressive treatment was started with daily 150 mg azathioprine and, initially, 50 mg prednisone. Within one week the serum creatinine concentration and ESR had fallen and the signs of urinary obstruction regressed.