A 26-year-old man had asymptomatic macroscopic hematuria. A left hydronephrotic sac outlined with a thin curvilinear shadow of calcium deposition was found in a plain film and stenosis at the ureteropelvic junction (UPJ) in a retrograde pyelogram. Left nephrectomy was performed and the fluid content was 1330 ml. Histologic examination showed subepithelial calcification of the renal pelvis and fibrous proliferation at the UPJ
