Wegener's granulomatosis in a patient with apparent drug-induced acute interstitial nephritis

We describe a patient whose clinical presentation was suggestive of drug-induced acute interstitial nephritis (AIN). A renal biopsy and serologic testing led instead to the diagnosis of Wegener's granulomatosis (WG) with necrotizing crescentic glomerulonephritis. Treatment with corticosteroids and cyclophosphamide resulted initially in complete recovery of renal function, and an exacerbation of acute renal failure after doses of these agents had been tapered responded to resumption of the original regimen. We report this case to emphasize the potentially identical presentations of AIN and WG. Since the two conditions are treated differently, we suggest that the diagnosis of AIN should be accepted only after biopsy confirmation.