Interstitial nephritis.

The clinical and pathological findings are reviewed in ten cases where renal biopsy showed abnormalities predominantly within the interstitium. In six the nephritis was considered to be drug-induced; in two the aetiology was slightly obscure but the most likely diagnosis was considered to be sarcoidosis. Of the remaining two cases one was chronic pyelonephritis and the other polyarteritis nodosa. The diagnosis and pathogenesis of the renal lesions are discussed and attention is drawn to the importance of distinguishing primary interstitial changes from those found in association with glomerular disease.