Combined hepatocellular-cholangiocarcinoma with angiosarcomatoid change: A case report with immunohistochemical study

Sarcomatoid combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a rare condition, with only 16 cases reported to date; however, there have been no reports of hepatic sarcomatoid carcinoma with angiosarcomatous features. Here, we report a rare case of cHCC-CCA with angiosarcomatoid changes in a 77-year-old man. The tumor was biphasic with malignant epithelial and mesenchymal components. Histologically, the epithelial component was concordant with classical type cHCC-CCA. The mesenchymal component included angiosarcomatoid cells growing in a vasoformative structure and undifferentiated spindle cells. Immunohistochemical analyses showed that angiosarcomatoid cells were positive for CD31, factor VIII-related antigen, and other angiosarcoma markers. Characteristically diffuse and strong expression of p53 protein was observed in the nuclei of angiosarcomatoid cells but not in carcinoma cells, suggesting that TP53 gene mutations commonly occur in these cells. Transitional zones were observed between HCC and spindle cells and between HCC and angiosarcomatoid cells. A small portion of undifferentiated spindle cells expressed pan-cytokeratin. These findings suggested that this extremely rare tumor developed from dedifferentiation or metaplastic changes of cHCC-CCA.