Oncocytoma : Vimentin
Oncocytomas usually express EMA, pancytokeratin, low molecular weight keratins, CD117, S100 protein and E-cadherin. Vimentin is negative or focally positive. In this image, vimentin is negative in the tumor cells but nicely highlights the vasculature between the tumor cell nests. CK7 is usually negative or shows only scattered positive cells which represent entrapped epithelial cells of distal convoluted tubules. CD10 and RCC marker are negative.