Isolated renal sarcoidosis: a rare presentation of a rare disease treated with infliximab.

Sarcoidosis is a multisystem disease characterized by noncaseating granulomatous reaction frequently involving the lymph nodes, lungs, liver, skin, and eyes. Acute renal failure (ARF) as an isolated manifestation of sarcoidosis is rare. We describe a case of sarcoidosis presenting as transient polyarthritis and ARF due to isolated granulomatous infiltration of the renal parenchyma. Renal biopsy showed granulomatous interstitial nephritis with noncaseating granulomas consistent with sarcoidosis. Bacterial, fungal, and mycobacterial infections were excluded. There was no evidence of extrarenal sarcoid involvement. Prednisone of 60 mg daily resulted in significant improvement in renal function. Because of recurrent flares on steroid taper and steroid toxicity, treatment with infliximab, an anti-tumor necrosis factor-alpha (TNF-alpha) antibody, was instituted and resulted in stabilization of renal function despite steroid taper. Although uncommon, renal sarcoidosis should be considered in the differential diagnosis of acute or chronic renal failure of uncertain etiology, as early diagnosis and treatment can lead to recovery of renal function and prevent interstitial fibrosis. Corticosteroids are mainstay of therapy. Steroid-dependent or refractory cases may respond to other immunosuppressants including anti-TNF-alpha agents.