Anti-cytokeratin 19 interacts with epithelia and epithelial cancers, such as carcinomas of the colon, stomach, pancreas, biliary tract, liver, and breast.1 In particular, anti-cytokeratin 19 is helpful in distinguishing hepatocellular carcinoma from intrahepatic cholangiocarcinoma, particularly when combined with cytokeratin 7, CAM5.2, Ber-EP4/MOC31, Hep Par-1, and TTF1. The identification of thyroid papillary carcinoma is another practical use.