Specificities are observed for some alterations and anatomical subtypes: frequent fibroblast growth factor receptor 2 (FGFR2) and isocitrate dehydrogenase 1/2 (IDH1/2) alterations are specific to intrahepatic cholangiocarcinomas (ICCs), whereas frequent ERBB2 oncogene alterations are specific to extrahepatic cholangiocarcinomas (ECCs) and gallbladder carcinomas (GBCs).