THE CASE FOR PARALLEL CLASSIFICATION OF BILIARY-TRACT AND PANCREATIC NEOPLASMS

Most primary epithelial neoplasms found in the intrahepatic and extrah epatic biliary tracts and the pancreas have similar histologic appeara nces. The degree of similarity of tumor types is greater than is commo nly appreciated and extends to rare neoplasms. It has been suggested t hat parallel classifications could be used for tumors arising in these sites. However, significant differences in terms used to denote histo logically identical neoplasms are found in the current World Health Or ganization (WHO) classification of biliary tract tumors and the new WH O classification of exocrine pancreatic neoplasms, Mutations of oncoge nes and abnormalities of tumor suppressor genes found in ductal adenoc arcinomas from the two sites are also similar, although they have some what different frequencies. These histologic and molecular similaritie s provide strong support for the use of parallel descriptive diagnosti c terminology for neoplasms arising in the pancreas and the biliary tr act, The revised WHO classification of exocrine pancreatic neoplasms a ccommodates most types of biliary tract neoplasms and provides a new b asis for standardization of nomenclature.