An immunohistochemical study of sarcomatoid liver carcinomas.

Six cases of primary hepatic carcinomas with a significant amount of sarcomatoid elements were examined by using immunohistochemical stainings. Four of the six cases were associated with ordinary hepatocellular carcinoma (HCC), one with cholangiocellular carcinoma (CCC), and one with mixed HCC and CCC. Alpha-fetoprotein and alpha-1-antitrypsin were negative in sarcomatoid cells of all cases; vimentin stained positively in sarcomatoid tumor cells in two of the six cases; and cytokeratin (CK8) was detected in five cases. The CK8 was not detected in tumor cells of two cases of hepatic angiosarcoma, two of metastatic leiomyosarcomas, and one of metastatic fibrosarcoma, although vimentin stained positively in all these true sarcomas. It was concluded that sarcomatoid dedifferentiation of liver carcinomas might derive from both HCC and CCC. In addition CK8 might be an excellent marker to make a differential diagnosis of sarcomatoid cancers from true metastatic or primary sarcomas of the liver.