Granulomas within renal epithelial neoplasms in patients with sarcoidosis: A causal association?

Sarcoidosis is a chronic granulomatous disease that can involve virtually every organ system, but most commonly presents as lung, skin, or lymph node disease. Although kidney involvement is usually clinically silent, granulomatous interstitial nephritis - the hallmark of renal sarcoidosis - can lead to functional impairment and organ failure. Also, recent studies have suggested an association between sarcoidosis and an increased risk of developing kidney tumors. While a sarcoid-like granulomatous reaction (SLGR) to renal epithelial neoplasms in patients without sarcoidosis has been well documented, direct involvement of the tumor parenchyma by sarcoidosis has been reported only rarely. Here we present two renal epithelial tumors directly involved by sarcoidosis with a common pattern of distribution of non-caseating granulomas.