Abstract
Biliary intraepithelial neoplasia (BilIN) for microscopical flat intraepithelial neoplasm and intraductal papillary neoplasm (IPN) for grossly visible papillary intraepithelial neoplasm of the biliary tract including the gallbladder are known. These lesions are thought to be followed by invasive cholangiocarcinoma and gallbladder carcinoma. BilIN is classifiable into BilIN-1 (low grade), BilIN-2 (intermediate grade) and BilIN-3 (high grade), and BilIN-3 includes intraepithelial carcinoma of the biliary tract. These intraepithelial lesions are described in New WHO classification of tumours of the digestive system (2010). In this classification, mucinous cystic neoplasm (MCN) of the liver and biliary tract is recommended to replace hepatobiliary cystadenoma/adenocarcinoma. Cystic variant of IPNB and peribiliary cysts should be differentiated from hepatobiliary MCN. New approach by using this standard classification expects new horizon of clinical practice and research of the biliary tract neoplasm.
