Hypersensitivity syndrome and granulomatous interstitial nephritis associated with allopurinol

We describe a 53-year-old woman with hypertension and chronic renal failure (serum creatinine 3.2 mg/dl) who developed fever, exfoliative dermatitis, hepatocellular injury, eosinophilia and decrease of renal function after receiving treatment with allopurinol (300 mg/day) for a week. 20 days after drug withdrawal, there were no changes in her clinical status so treatment with prednisone (7 mg/kg/day) was started, leading to slow recovery of renal function and systemic symptoms. Steroid therapy vias tapered off a month later, when the previous serum creatinine levels were achieved. Renal biopsy showed diffuse interstitial fibrosis and noncaseating granulomas, findings that in the absence of infectious or systemic granulomatous disease, we attribute due to the previous allopurinol therapy. The association between the allopurinol hypersensitivity syndrome and granulomatous interstitial nephritis (GIN) is discussed and some aspects of GIN are briefly reviewed.