Idiopathic retroperitoneal fibrosis: case report.

A 45-year-old woman was admitted to the hospital because of abdominal pain, fever, and weight loss. Laboratory tests performed on admission revealed raised inflammatory markers. Ultrasonography of the abdomen showed dilatation of the pyelocalyceal system of the left kidney, while computed tomography showed retroperitoneal concentric periaortic mass extending to common iliac arteries and entrapping the left ureter. We established the diagnosis of idiopathic retroperitoneal fibrosis (RPF). JJ catheter was placed in the left ureter, and treatment with corticosteroids and azathioprine was started. Follow-up examinations showed a gradual improvement, namely a progressive remission of the retroperitoneal mass and normalization of both erythrocyte sedimentation rate and C-reactive protein concentration. Case reports, including our paper, and small case series showed azathioprine to be particularly effective in the treatment of RPF.