CLDN4 and cholangiocarcinoma: That is, EZH2 similarly to other CC markers e.g. CK7, CK19, claudin 4 [28] does not provide major help in distinguishing cholangiocarcinomas from metastatic tumors, but it does seem to be able to differentiate reactive/hamartomatous biliary structures and benign biliary tumors from malignant ones.