Intraoperative Evaluation of Hepatic Biliary Lesions

IntroduCtIon Most hepatic biliary lesions are benign and incidentally discovered during procedures unrelated to the liver. Benign bile duct proliferations are gray–white subcapsular nodules that are often multiple, so it is not surprising that their detection results in more liver frozen sections than any other finding. In contrast, a diagnosis of intrahepatic cholangiocarcinoma is almost always known prior to surgery. Thus, diagnostic frozen sections are rarely performed. Cholangiocarcinomas that involve the liver occur either in the proximal extrahepatic bile ducts and directly extend into the liver (hilar cholangiocarcinoma or Klatskin tumor) or they arise from the intrahepatic biliary tree. Intrahepatic cholangiocarcinomas are subclassified in two broad groups based on their anatomic location in the porta hepatis and/or large ramifying ducts (central cholangiocarcinoma) or smaller ducts (peripheral cholangiocarcinoma). Intraoperative consultations for cholangiocarcinoma are usually limited to bile duct margin evaluation on tumors that involve the perihilar region, although surgeons may request evaluation of parenchymal margins for peripheral cholangiocarcinomas. In the former situation, frozen sections are obtained from the main hepatic resection specimen or separately submitted segments of extrahepatic bile duct. The purpose of this chapter is to discuss the following: (1) the histologic features of benign bile duct lesions, (2) criteria that aid their distinction from carcinoma, and (3) issues related to margins of resection for malignant biliary-type tumors that involve the liver. Extrahepatic biliary neoplasia is discussed in further detail in Chapter 6.