KRT7 and kidney neoplasm: In renal tumors, the most common CK is CK7, a low-molecular-weight CK which is highly expressed in most papillary renal cell carcinomas (PRCCs), ChrRCCs, collecting duct carcinomas (CDCs), and almost all CPRCTs and mucinous tubular and spindle cell carcinomas (MTSCCs) [59].