CA9 and nonpapillary renal cell carcinoma: In our casuistry, in the examined ccRCC cases with an RCC-FMS-like histotype, not only CK7, as already discussed, but also CAIX (weak and variable from box- to cup-shaped), CK34betaE12 (negative) and CD10 (patchy positive) were incongruent with RCC-FMS diagnosis, on the one hand, and confirmatory of the non-diriment histology, on the other, of the multiform histochemical response of ccRCC.