Emphysematous pyelonephritis in a xanthogranulomatous kidney. An unusual cause of pneumoperitoneum.

Emphysematous pyelonephritis is a rare, life-threatening suppurative infection of the renal parenchyma and perinephric tissues. The disease is encountered primarily in patients with diabetes mellitus or ureteral obstruction associated with perinephric and intrarenal gas. Causative organisms are those normally found in the urinary and gastrointestinal tracts; however, anaerobic bacteria have been demonstrated in only 1% of cases. We describe a case of emphysematous pyelonephritis, which presented as an acute abdomen with pneumoperitoneum in a nondiabetic patient. No visceral injury was found at laparotomy. Multiple gas-producing organisms, including Clostridium ramosum (not previously reported, to our knowledge), were the cause of the free intraperitoneal and perinephric air. Subsequent radical nephrectomy revealed a xanthogranulomatous kidney. An aggressive surgical approach combined with intensive antibiotic therapy, after aerobic and anaerobic culture of excised tissue, is lifesaving.