Renin expression in adult renal epithelial tumors with granular cells

Renal cell tumors have been shown to be associated with secretory products, including renin, but the frequency of renin expression is not known. To investigate renin expression in epithelial renal neoplasms, we examined a series of 89 adult renal tumors with granular cells using a monoclonal antiserum to detect the hormone by immunohistochemistry (IHC) and their association with hypertension. We found that 25 of 89 tumors (28.1%) contained immunoreactivity for renin. Oncocytomas had the highest percentage of cases with renin expression: 8 of 13 (61.5%), all of these with diffuse immunostaining. Renin was detected in 31.6% of 38 chromophobe carcinomas and in 12.5% of 24 conventional carcinomas. Renin was not detected in collecting duct carcinomas or in mucinous tubular and spindle cell carcinomas. Systemic hypertension was detected in 11 of 25 (44%) patients with renin expression and in 32 of 64 (50%) patients without renin immunolabeling (p=0.64). After tumor resection, patients with renin expression and high blood pressure showed no hypertension remission. In conclusion, renin is frequently expressed in renal epithelial neoplasms with granular cells, mainly in oncocytomas, but this renin appears clinically inactive.