Renal Sarcoidosis Presenting as Acute Kidney Injury With Granulomatous Interstitial Nephritis and Vasculitis

Among the various renal manifestations of sarcoidosis, granulomatous inflammation confined to the tubulointerstitial compartment is the most commonly reported finding. We present the case of a 66-year-old man with acute kidney injury, hypercalcemia, mild restrictive pulmonary disease, and neurologic signs of parietal lobe dysfunction. Kidney biopsy showed diffuse interstitial inflammation with noncaseating granulomas that exhibited the unusual feature of infiltrating the walls of small arteries with destruction of the elastic lamina, consistent with granulomatous vasculitis. The findings of granulomatous interstitial nephritis on kidney biopsy, hypercalcemia, and possible cerebral and pulmonary involvement in the absence of other infectious, drug-induced, or autoimmune causes of granulomatous disease established the diagnosis of sarcoidosis. Pulse methylprednisolone followed by maintenance prednisone therapy led to improvement in kidney function, hypercalcemia, and neurologic symptoms. Vasculocentric granulomatous interstitial nephritis with granulomatous vasculitis is a rare and under-recognized manifestation of renal sarcoidosis.