[Acute granulomatous interstitial nephritis of drug origin]

Epithelioid cell granulomas within the renal interstitium are frequently found in drug-associated acute interstitial nephritis. Their presence is a strong argument in favour of an immunologically mediated nephropathy especially when extrarenal symptoms are absent and if the interstitial infiltrate does not contain eosinophils. They are probably due to a delayed hypersensitivity reaction. Unfortunately, there is no reliable experimental model. The high incidence of permanent renal damage observed in this type of nephritis indicates an early corticosteroid therapy, particularly when renal function does not rapidly improve after withdrawal of the offending drug.