Oncocytoma : CK7
Oncocytomas usually express EMA, pancytokeratin, low molecular weight keratins, CD117, S100 protein and E-cadherin. Vimentin is negative or focally positive. CK7 is usually negative or shows only scattered positive cells which represent entrapped epithelial cells of distal convoluted tubules (as shown in this image). CD10 and RCC marker are negative.