In CCA patients with available CA125 serum levels, 100% (4/4) of MUC16 (−) patients were also negative for serum CA125 while 75% (3/4) of the MUC16 (+) patients were also positive for serum CA125 in our study, which may serve as the first indication of a possible correlation between MUC16 assessment by IHC and serum levels. Here, MUC16 is linked to cholangiocarcinoma.