Large-duct iCCA and pCCA more frequently had the loss of SMAD4 expression and MDM2 amplifications than small-duct iCCA, whereas the loss of BAP1 expression and IDH1 mutations were mostly restricted to small-duct iCCA.
Immunohistochemistry was performed on 6 mucinous and 12 conventional iCCs with matched age, sex, and stage, which revealed positive immunoreactivity in MUC1 (83% versus 58%), MUC2 (33% versus 17%), MUC5AC (100% versus 42%), MUC6 (50% versus 0), CK7 (83% versus 83%), CK20 (0 versus 17%), CDX2 (17% versus 0), p53 (67% versus 67%), Smad4 (67% versus 58%), and EGFR (83% versus 42%) in mucinous and conventional iCCs, respectively.