Reversible renal failure from isolated granulomatous renal sarcoidosis

A patient presented with a 6 month history of progessive renal failure. Serum creatinine was 7.1 mg/100 ml, creatinine clearance 4 ml/minute and hematocrit 22%. Skin tests for tuberculosis, trichophyton, SK/SD and candida were all unreactive and all cultures were negative or showed normal growth. A renal biopsy revealed non-caseating epithelial granulomas and foreign body multinucleated giant cells. No deposits or micro-organisms were seen on electron microscopy. Bone marrow and lymph node biopsies were unremarkable and no lung pathology was present. Therapy with systemic prednisone produced a dramatic improvement with serum creatinine diminishing to 1.3 mg/100 ml, creatinine clearance increasing to 81 ml/minute and hematocrit improving to 39%. A search of the literature has failed to reveal similar reports of reversible renal failure from isolated granulomatous renal sarcoidosis.