For instance, CCA that has been derived from large cholangiocytes is predominantly categorized as perihilar CCA with well to moderately differentiated mucin-producing cells and periductal infiltrating growth pattern, whereas CCA that is derived from small cholangiocytes is predominantly categorized as intrahepatic CCA and largely contains non–mucin-producing cells and has mass-forming growth patterns3,4. This evidence concerns the gene MUC5AC and cholangiocarcinoma.