- Tumor histology and immunohistochemical studies:

- Tumor extension: Invades lamina propria Invades muscular layer Invades perimuscular connective tissue on the peritoneal side without serosal involvement Invades perimuscular connective tissue on the hepatic side without liver involvement Perforates serosa (visceral peritoneum) Directly invades liver Directly invades other adjacent organ(s) or structure(s): Stomach Directly invades other adjacent organ(s) or structure(s): Duodenum Directly invades other adjacent organ(s) or structure(s): Colon Directly invades other adjacent organ(s) or structure(s): Pancreas Directly invades other adjacent organ(s) or structure(s): Extrahepatic bile ducts Directly invades other adjacent organ(s) or structure(s): Omentum Directly invades other adjacent organ(s) or structure(s): Main portal vein Directly invades other adjacent organ(s) or structure(s): Hepatic artery Directly invades other adjacent organ(s) or structure(s): Other (specify): No evidence of primary tumor Cannot be assessed

Dysplasia/adenoma Cholelithiasis Chronic cholecystitis Acute cholecystitis Intestinal metaplasia Diffuse calcification (porcelain gallbladder) Primary sclerosing cholangitis

- Other (specify):