Xanthogranulomatous pyelonephritis with renocolic fistula and coexistent contralateral renal carcinoma.

The presence of contralateral renal tumour in a case eventually found to have Xanthogranulomatous Pyelonephritis (XP) resulted in a wrong preoperative diagnosis of tumour with bowel fistula. The patient's prior history of bladder tumour and multiple renal cysts is also discussed, along with the retrospective finding of very minor changes in an early angiogram.