We report on a 47-year-old man with hydronephrosis secondary to ureteropelvic junction obstruction with renal pelvic calcification. Calcium deposit was found in the wall of the severely dilated renal pelvis. Pathological examination revealed a damaged and hyalinized fibrous renal pelvic wall while serum calcium level was normal. Thus, we speculated that this calcification was dystrophic. Chronic extensive dilatation with intermittent hemorrhage of the renal pelvic wall may have caused this dystrophic renal pelvic calcification.
