Component with abundant immune‐related cells in combined hepatocellular cholangiocarcinoma identified by cluster analysis

Combined hepatocellular cholangiocarcinoma (cHCC‐CCA) is a heterogeneous tumor sharing histological features with hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). The tumor immune microenvironment (TIME) of cHCC‐CCA is unclear. We compared the TIME of cHCC‐CCA with that of HCC and iCCA. Twenty‐three patients with cHCC‐CCA after hepatectomy were evaluated in this study. Twenty‐three patients with iCCA and HCC were also included. iCCA was matched for size, and HCC was matched for size and hepatitis virus infection with cHCC‐CCA. Immune‐related cells among the iCCA‐component of cHCC‐CCA (C‐com), HCC‐component of cHCC‐CCA (H‐com), iCCA, and HCC were assessed using multiplex fluorescence immunohistochemistry. Among C‐com, H‐com, iCCA, and HCC, multiple comparisons and cluster analysis with k‐nearest neighbor algorithms were performed using immunological variables. Although HCC had more T lymphocytes and lower PD‐L1 expression than iCCA (P < 0.05), there were no significant differences in immunological variables between C‐com and H‐com. C‐com tended to have more T lymphocytes than iCCA (P = 0.09), and C‐com and H‐com had fewer macrophages than HCC (P < 0.05). In cluster analysis, all samples were classified into two clusters: one cluster had more immune‐related cells than the other, and 12 of 23 H‐com and eight of 23 C‐com were identified in this cluster. The TIME of C‐com and H‐com may be similar, and some immunological features in these components were different from those in HCC and some iCCA. Cluster analysis identified components with abundant immune‐related cells in cHCC‐iCCA.