Twenty-five cases were morphologically and immunophenotypically consistent with CCPRCC; all of them showed diffuse CK7 expression and cup-like reactivity with CAIX.
By immunohistochemistry, 7/9 (78%) of the clear cell cases were diffusely positive for both CK7 and CAIX resembling the pattern seen in clear cell papillary renal cell carcinoma.
Almost all CCPRCC-like tumors (82%) lacked the characteristic immunoprofile of sporadic CCPRCC (CK7, CAIX, CD10, AMACR), often showing diffuse CD10 labeling (64%), negative or focal CK7 reactivity (55%), or both (18%).