[A case of retroperitoneal fibrosis demonstrating a remarkable response to steroids].

We present a case of idiopathic retroperitoneal fibrosis that demonstrated a remarkable response to steroids. The patient, a 73-year-old man, complained of left flank pain and weight loss. Erythrocyte sedimentation rate was elevated and both CRP and antinuclear factor were positive. DIP showed left hydronephrosis, which proved to be due to the stenosis of the left ureter at the level of L5 by retrograde pyelography. Then abdominal computed tomography revealed a large retroperitoneal mass with the density of soft tissue in which the left ureter was involved. Based upon the above findings, we made the diagnosis of idiopathic retroperitoneal fibrosis. After confirming histological diagnosis by biopsy from the mass, we performed left ureterolysis. Since then, he has been treated with steroid administration. Now we can recognize a remarkable reduction of the mass in abdominal CT and improvement of the left renal function in DIP. We reviewed the association of autoimmune disease with idiopathic retroperitoneal fibrosis and recent therapies for this disease.