What is the most common type of cholangiocarcinoma?

Cholangiocarcinoma primarily arises from the epithelial cells of the bile ducts, and the most common histological subtype of this cancer is adenocarcinoma. Adenocarcinomas are tumors that develop from glandular tissue, which is exactly the type of tissue found in the bile ducts. This makes adenocarcinomas the predominant form of cholangiocarcinoma, reflecting the nature of the cells involved in the disease.

Other types of cancers listed, such as sarcomas, carcinoids, and neuroendocrine tumors, are less frequently associated with the bile ducts. Sarcomas arise from mesenchymal tissues and are not tied to the epithelial origin of cholangiocarcinoma. Carcinoids and neuroendocrine tumors originate from neuroendocrine cells and are also not common in the context of cholangiocarcinomas. Thus, adenocarcinomas stand out as the most common and clinically relevant type when discussing cholangiocarcinoma.