Neuroendocrine Tumors of the Hepatobiliary Tract

Abstract

Neuroendocrine neoplasms of the hepatobiliary tract are rare neoplasms that derive from neuroendocrine cells located in the bile duct mucosa and several compartments of the liver proper. These neoplasms are divided into neuroendocrine tumors (NET) and neuroendocrine carcinomas (NEC). Well-differentiated NET (G1) have previously been termed carcinoid tumors. Most of neuroendocrine neoplasms that are known from extrahepatic organs and tissues also develop in the hepatobiliary tract, except tumors that originate from distinct specialized neuroendocrine/endocrine cell types that do not exist in this organ. The bile ducts are a well-known primary location of welldifferentiated carcinoid-type NETs. Neuroendocrine carcinomas can also develop in bile ducts and the liver, but are unusual lesions. Intriguing primary neuroendocrine neoplasms of the liver are undifferentiated small cell and large cell carcinomas, which have to be distinguished from the more common liver metastases of extrahepatic tumors with this morphology.