Pathological aspects of so called "hilar cholangiocarcinoma"

Cholangiocarcinoma(CC) arising from the large intrahepatic bile ducts and extrahepatic hilar bile ducts share clinicopathological features and have been called hilar and perihilar CC as a group.However,"hilar and perihilar CC" are also used to refer exclusively to the intrahepatic hilar type CC or,more commonly,the extrahepatic hilar CC.Grossly,a major distinction can be made between papillary and non-papillary tumors.Histologically,most hilar CCs are well to moderately differentiated conventional type(biliary) carcinomas.Immunohistochemically,CK7,CK20,CEA and MUC1 are normally expressed,being MUC2 positive in less than 50% of cases.Two main premalignant lesions are known:biliary intraepithelial neoplasia(BilIN) and intraductal papillary neoplasm of the biliary tract(IPNB).IPNB includes the lesions previously named biliary papillomatosis and papillary carcinoma.A series of 29 resected hilar CC from our archives is reviewed.Most(82.8%) were conventional type adenocarcinomas,mostly well to moderately differentiated,although with a broad morphological spectrum;three cases exhibited a poorly differentiated cell component resembling signet ring cells.IPNB was observed in 5(17.2%),four of them with an associated invasive carcinoma.A clear cell type carcinoma,an adenosquamous carcinoma and two gastric foveolar type carcinomas were observed.

Pathological features and diagnosis of intraductal papillary mucinous neoplasm of the pancreas

Intraductal papillary mucinous neoplasm(IPMN) of the pancreas is a noninvasive epithelial neoplasm of mucinproducing cells arising in the main duct(MD) and/or branch ducts(BD) of the pancreas.Involved ducts are dilated and filled with neoplastic papillae and mucus in variable intensity.IPMN lacks ovarian-type stroma,unlike mucinous cystic neoplasm,and is defined as a grossly visible entity(≥ 5 mm),unlike pancreatic intraepithelial neoplasm.With the use of high-resolution imaging techniques,very small IPMNs are increasingly being identified.Most IPMNs are solitary and located in the pancreatic head,although 20%-40% are multifocal.Macroscopic classification in MD type,BD type and mixed or combined type reflects biological differences with important prognostic and preoperative clinical management implications.Based on cytoarchitectural atypia,IPMN is classified into low-grade,intermediategrade and high-grade dysplasia.Based on histological features and mucin(MUC) immunophenotype,IPMNs are classified into gastric,intestinal,pancreatobiliary and oncocytic types.These different phenotypes can be observed together,with the IPMN classified according to the predominant type.Two pathways have been suggested:gastric phenotype corresponds to less aggressive uncommitted cells(MUC1-,MUC2-,MUC5 AC +,MUC6 +) with the capacity to evolve to intestinal phenotype(intestinal pathway)(MUC1-,MUC2 +,MUC5 AC +,MUC6- or weak +) or pancreatobiliary /oncocytic phenotypes(pyloropancreatic pathway)(MUC1 +,MUC 2-,MUC5 AC +,MUC 6 +) becoming more aggressive.Prognosis of IPMN is excellent but critically worsens when invasive carcinoma arises(about 40% of IPMNs),except in some cases of minimal invasion.The clinical challenge is to establish which IPMNs should be removed because of their higher risk of developing invasive cancer.Once resected,they must be extensively sampled or,much better,submitted in its entirety for microscopic study to completely rule out associated invasive carcinoma.