KRT7 and renal cell carcinoma: The most distinctive feature of HLRCC-associated RCC is the presence of characteristically large nuclei with inclusion-like eosinophilic nucleoli and perinuclear clearing [63,73] Immunohistochemically, HLRCC-associated RCC is typically negative for high-molecular weight cytokeratins (CK19 and 34betaE12) and CK7, which are positive in collecting duct carcinoma, and can be included in a differential diagnosis with HLRCC-associated RCC.