Figure 1.

Based on the relative anatomical location within the liver, CCA can be categorized into three types: ICCA, perihilar CCA (pCCA), and dCCA. ICCA is characterized by bile duct cancer within the liver, with histological subtypes including mass-forming, periductal infiltrating, and intraductal growing; pCCA refers to a secondary branch located in the hepatic duct, specifically from the common bile duct above the cystic duct to the liver, and is histologically classified as a klatskin tumor; dCCA denotes located outside the liver, primarily presenting as adenocarcinoma histologically. GBC: gallbladder cancer; FGFR2: fibroblast growth factor receptor 2