Intracholecystic papillary-tubular neoplasm of the gallbladder

Abstract

The pathologic description for neoplastic polyps of the gallbladder (GB) was controversial. Although current WHO suggest adenoma and papillary neoplasm for precursor lesions, the distinction is not clear. In recent study for 123 GB cases, we found tumoral preinvasive neoplasms (≥ 1 cm) were analogous to their pancreatic and biliary counterparts. They show variable cellular lineages, a spectrum of dysplasia, and a mixture of papillary or tubular growth patterns, often with significant overlap, warranting their classification under one unified parallel category, intracholecystic papillary-tubular neoplasm (ICPN). We found that ICPN have similarity with intraductal papillary-mucinous neoplasm of pancreas (IPMN) and intraductal papillary neoplasm of bile duct (IPNB). ICPN of GB showed similar cell lineage and mucin core protein expression pattern with IPMN and IPNB. It is suspected that ICPN might be a GB counterpart with IPMN and IPNB. We think these polypoid precursor lesions of pancreatobiliary tract and GB may correspond to tumoral intraepithelial neoplasia, whereas the pancreatic intraepithelial neoplasia and biliary intraepithelial neoplasia correspond to the flat intraepithelial neoplasia. We also found there is a geographic difference of ICPN incidence between East and West. ICPN was more common in East whereas conventional flat dysplasia was more frequently found in West.