Clinicopathological, radiologic, and molecular study of 23 combined hepatocellular-cholangiocarcinomas with stem cell features, cholangiolocellular type.

Cholangiolocellular carcinoma is a type of intrahepatic cholangiocarcinoma (ICC). According to the 2010 World Health Organization classification, this carcinoma is a combined hepatocellular-cholangiocarcinoma with stem cell features, cholangiolocellular type (CHC-SC-CLC). The aim of this study was to compare the clinicopathological characteristics of CHC-SC-CLC and conventional ICC. Based on the gross and histologic characteristics, we divided consecutive ICC tumors into CHC-SC-CLC (n = 23), mass-forming (MF; n = 57), and non-MF (n = 22) groups. Compared with MF and non-MF groups, the CHC-SC-CLC group featured history of hepatolithiasis or bile duct operation in significantly fewer patients (4.3% versus 14.8% and 86.4%, respectively; P < .001) and was more common in the right lobe (70% versus 47% and 27%; P = .033) but lower frequency of invasive growth or peritumoral Glisson sheath invasion (61% and 22% versus 77% and 33% and 100% and 86%, respectively; P = .002 and P < .001) and absence of mucous production (0 versus 77% and 96%; P < .001). In CHC-SC-CLCs, the mutation rate of isocitrate dehydrogenase 1 (IDH1) or IDH2 was significantly higher (35%) than in MF (4%) or non-MF (0) ICCs (P < .001). The 1-, 3-, and 5-year postresection survival rates were also significantly better with CHC-SC-CLCs (93%, 79%, and 52%, respectively) than with MF (72%, 46%, and 40%) or non-MF (61%, 18%, and 0) ICCs (P = .041). Thus, CHC-SC-CLC tumors demonstrated an indolent growth pattern, more frequent IDH1/2 gene mutations, and better prognosis than did MF or non-MF ICC tumors.