ABSTRACT
A case of a 52-year-old man with retroperitoneal fibrosis and a horseshoe kidney is presented. Horseshoe kidney is one of the most common renal anomalies and complicated with urinary tract infection, hydronephrosis, calculi, tumor of the renal pelvis, and other multiple congenital abnormalities. Idiopathic retroperitoneal fibrosis is a rare disease characterized by the presence of a retroperitoneal tissue, consisting of chronic inflammation and marked fibrosis, which often entraps ureters or other abdominal organs. The correlation between horseshoe kidney and retroperitoneal fibrosis has not been described. We report a rare case of idiopathic retroperitoneal fibrosis with horseshoe kidney disease demonstrating good response to steroid therapy.