Abstract

Combined hepatocellular-cholangiocarcinoma (CHC) is an extremely rare form of primary liver cancer having features of both hepatocellular and biliary epithelial differentiation. The incidence of CHC was 1.0-6.3% of all primary liver cancers. Since Allen and LIsa first described the features of this tumor in 1949, Allen’s classification has been widely used. This classification includes: type A, double cancer of HCC and CC, with HCC and CC present at different sites without contact; type B, HCC and CC are present at adjacent sites and mingle with continued growth; and type C, HCC and CC are mixed, growing within the same tumor. CHC are often confused with pseudoglandular growth pattern in HCC, but this has led to the mistaken impression that CHC are common. Histologically, only type C displays the characteristic of genuine mixture of both HCC and CC elements, and only Allen’s type C was included and regarded as true CHC in many published studies of CHC. With regard to the tumorigensis of CHC, the following possibilities have been proposed: 1st, the CC component arises from the main HCC tumor, and 2nd, the entire cancer arises from a stem cell potentially differentiating into hepatocytes and bile duct epithelium. In this review, I will describe the tumorigenesis of CHC and introduce the hepatic stem cell, such as hepatic progenitor cells.

• Keywords: Hepatocellular carcinoma;Cholangiocarcinoma;Combined hepatocellular-cholangiocarcinoma;Progenitor cell