Xanthogranulomatous pyelonephritis complicated by emphysematous pyelonephritis in a hemodialysis patient.

Xanthogranulomatous pyelonephritis and emphysematous pyelonephritis are two uncommon variants of pyelonephritis. The combined occurrence is very rare and has not been described in dialysis patients. We report a 78-year-old woman with end-stage renal disease receiving chronic hemodialysis who presented with a one-week history of vague abdominal pain. During the previous 4 months, she had experienced four episodes of urinary tract infection presenting with fever and pyuria which were improved by antibiotic therapy. The urine cultures yielded Klebsiella pneumoniae at all events. Abdominal computed tomography showed the right kidney replaced by multiple hypodense masses. A kidney biopsy demonstrated characteristic pictures of xanthogranulomatous pyelonephritis. Subsequent computed tomography showed gas bubbles formation in the right renal masses suggestive of emphysematous pyelonephritis. Because the patient refused surgical nephrectomy, percutaneous needle aspiration with prolonged antibiotic treatment was done. Follow-up computed tomography demonstrated dramatic regression of the renal mass. This case suggests that xanthogranulomatous pyelonephritis can be complicated by emphysematous pyelonephritis. Furthermore, the unique features in end-stage renal disease patients make the diagnosis of xanthogranulomatous pyelonephritis more difficult.