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.
为肿瘤供血的微血管系统存在多种类型：包括作为浸润性癌肿瘤微环境（TME）组成部分、具有类似伤口愈合反应的“新生血管”（新生血管生成）；以及被肿瘤用作供血血管的“既存血管”（血管共择），这类血管更易在富血管器官中形成。本文结合既存血管与血管共择现象，对胆道系统肿瘤的微血管结构进行综述。在肝胆系统中，肝内大胆管、肝外胆管（大胆管）及胆囊与肝小叶均为高度血管化区域。大胆管中，胆管衬里上皮与深层毛细血管（胆管周围毛细血管丛[PCP]）构成胆管上皮-PCP排列结构，而肝细胞-肝窦排列则构成肝小叶。胆管癌（CCA）与胆囊癌（GBC）是主要的胆道恶性肿瘤。CCA可分为远端胆管癌（dCCA）、肝门部胆管癌（pCCA）和肝内胆管癌（iCCA），其中iCCA又细分为小胆管型（SD-iCCA）与大胆管型（LD-iCCA）。近年来研究提出，高级别胆管上皮内瘤变（BilIN）、胆管内乳头状肿瘤（IPNB）、幽门腺腺瘤（PGA）及胆囊内乳头状肿瘤（ICPN）分别是LD-iCCA、p/dCCA和GBC的癌前病变。在大胆管与胆囊中，所有高级别BilIN和PGA病例、约半数IPNB病例以及三分之一结构较简单的ICPN病例均被发现劫持PCP作为其支持血管（血管共择）；而p/dCCA、LD-iCCA和GBC则由伴随纤维间质的新生血管供血。其余结构复杂的ICPN和IPNB病例的管腔内成分则呈现稀疏的毛细血管分布且无纤维间质，这种独特的微血管结构既不同于血管共择也不同于新生血管生成。对于侵犯肝小叶的iCCA，部分SD-iCCA可取代肝细胞索并利用既存肝窦作为共择血管。对既存血管的可视化研究可能成为评估CCA及其癌前病变恶性进展与血管供血情况的新型病理学工具。
肿瘤(癌症)患者之家