Search Results (2)

There are several types of microvasculature supplying neoplasms: “newly formed blood vessels” (neoangiogenesis), which are a component of the tumor microenvironment (TME) of invasive carcinoma with wound healing-like reaction; and “pre-existing blood vessels”, which are used as tumor-supplying vessels by neoplasms (co-option vessels) and are likely to develop in hypervascularized organs. We herein review the microvasculature of neoplasms of biliary tract with reference to pre-existing vessels and vessel co-options. In the hepatobiliary system, intrahepatic large and extrahepatic bile ducts (large bile ducts) and the gallbladder as well as hepatic lobules are highly vascularized regions. In large bile ducts, the biliary lining epithelia and underlining capillaries (peribiliary capillary plexus [PCP]) form the biliary epithelia–PCP alignment, whereas the hepatocyte–sinusoid alignment composes hepatic lobules. Cholangiocarcinoma (CCA) and gallbladder carcinoma (GBC) are the main biliary tract carcinomas. CCA is subdivided into distal (d/CCA), perihilar (pCCA), and intrahepatic (iCCA), and iCCA is subdivided into small duct type (SD-iCCA) and large duct type (LD-iCCA). High-grade biliary intraepithelial neoplasm (BilIN), intraductal papillary neoplasm of the bile duct (IPNB), pyloric gland adenoma (PGA), and intracholecystic papillary neoplasm (ICPN) have recently been proposed as the precursors of LD-iCCA, p/dCCA, and GBC. In the large bile ducts and gallbladder, all cases of high-grade BilIN and PGA, about half of IPNB, and one-third of ICPN with less-complicated structure were found to have hijacked the PCP as their supporting vessels (vessel co-option), while p/dCCA, LD-iCCA, and GBC were supplied by neo-angiogenetic vessels associated with fibrous stroma. The intraluminal components of the remaining cases of ICPN and IPNB with complicated structure presented sparse capillaries without fibrous stroma, a unique microvasculature different from that of co-option or neoangiogenesis. Regarding iCCA showing invasion into the hepatic lobules, some SD-iCCAs replaced hepatocytic cords and used pre-existing sinusoids as co-opted vessels. Visualization of pre-existing vessels could be a new pathological tool for the evaluation of malignant progression and of vascular supply in CCAs and its precursors. Full article

Carcinomas and precursor lesions of the biliary tract belong to a spectrum of pancreatobiliary neoplasms that share common histology and cell lineages. Over the past two decades, preinvasive precursors to biliary tract carcinomas (BTCs) have been identified such as high-grade biliary intraepithelial neoplasm (high-grade BilIN), intraductal papillary neoplasm of bile duct (IPNB) and intracholecystic papillary neoplasm of the gallbladder (ICPN). While a majority of these precursors may arise from the biliary tract mucosa, some originate from the peribiliary glands and Rokitansky-Aschoff sinuses in the walls of the biliary tract. High-grade BilIN is a microscopically identifiable intraepithelial neoplasm of the biliary tract, whereas IPNB and ICPN are grossly visible intraductal or intraluminal preinvasive neoplasms in the bile duct and gallbladder, respectively. These neoplasms show characteristic histologic features according to four cell lineages and two-tiered grading, and show intraepithelial spreading to the surrounding mucosa and involve non-neoplastic glands in the walls of the biliary tract. These precursors are not infrequently associated with stromal invasion, and high-grade BilIN, in particular, are frequently identified in the surrounding mucosa of BTCs. Taken together, it seems likely that progression from these precursors to invasive carcinoma is a major process in biliary carcinogenesis. Full article