KRT7 and oncocytic adenoma: The main diagnostic dilemma is between oncocytoma and ChRCC, but unlike the latter, oncocytomas generally have fewer nuclear membrane irregularities and a far denser vascular network, whereas ChRCC shows more trabecular growth. Cytokeratin 7 is usually negative in oncocytoma but may be focally positive in clear cell RCC and is positive in papillary and chromophobe RCC.