[Allopurinol-induced chronic granulomatous interstitial nephritis].

Although drug induced interstitial nephritis is a relatively common cause of renal failure,granulomatous forms remain a rare condition. The development of a chronic granulomatous interstitial nephritis due to allopurinol is exceptional, only three cases have been described previously. We report on a patient who presented a granulomatous interstitial nephritis after 10 years of allopurinol administration (300 mg/day). At diagnosis, he had end stage renal disease and dialysis treatment was needed. Two months after drug withdrawal and on corticoid treatment a slow recovery of renal function was observed, allowing the interruption of dialysis. Two years after, the creatinine clearance is 23 ml/min,being dialysis free. We discuss the differential diagnosis of granulomatous interstitial nephritis and its rare association with allopurinol treatment.