Cytokeratin 8 belongs to the type B (basic) subfamily of high molecular weight keratins and exists in combination with cytokeratin 18. Cytokeratin 8 is primarily found in the non squamous epithelia and is present in majority of adenocarcinomas and ductal carcinomas. It is absent in squamous cell carcinomas. Hepatocellular carcinomas are defined by the use of antibodies that recognize only cytokeratin polypeptides 8 and 18.