S100 Expression in Oncocytoma and Chromophobe Renal Cell Carcinoma: An Immunohistochemical Study

Oncocytoma and chromophobe renal cell carcinoma may show a certain degree of histological overlap. The problem of differentiating both types is expected to increase because of the more frequent use of needle biopsies to diagnose small renal masses. In this study. The expression and the possible diagnostic utility of S 100 was evaluated in both oncocytoma and chromophobe renal cell carcinoma, using immunohistochemistry. Ten cases of oncocytoma and 10 cases of chro- mophobe renal cell carcinoma were used for the immunohistochemical study. Nine cases of chromophobe renal cell carcinomas (90%) showed no reaction with antibody to S 100. Only one chromophobe renal cell carcinoma (10%) was positive. Eight cases of renal oncocytomas (80%) gave positive reactions with antibody to S100, while two cases (20%) showed no reaction with antibody to S 100. In conclusion: A significant difference in S 100 immunoexpression between chromophobe renal cell carcinomas and oncocytomas has been detected (p 0.001) and it can be used as a differentiating point between both subtypes.