Primary vs metastatic hepatic carcinoma: An immunohistochemical study of 34 cases

The distinction between primary and metastatic hepatic epithelial malignant neoplasms can often be difficult if histologic features alone are used. The purpose of this study was to determine whether certain immunohistochemical markers could be used to aid in the diagnosis. The cases that were studied included 14 hepatocellular carcinomas, 10 cholangiocarcinomas, and seven metastatic adenocarcinomas; three cases of poorly differentiated carcinoma (not otherwise specified) were also studied. The antibodies that were chosen included α-fetoprotein, α₁-antitrypsin, monoclonal carcinoembryonic antigen, Leu-M1, B72.3, factor XIIIa, and Le(x). We found that the cases of hepatocellular carcinoma displayed cytoplasmic reactivity for α₁-antitrypsin, α-fetoprotein, and factor XIIIa. The cases of cholangiocarcinoma showed membranous and cytoplasmic reactivity for Le(x) but only cytoplasmic reactivity for Leu-M1 and B72.3, whereas the opposite pattern of staining was found in cases of metastatic adenocarcinoma. We conclude that immunohistochemical studies can be useful in the distinction of primary vs metastatic hepatic malignant neoplasms and recommend a panel of α₁-antitrypsin, α-fetoprotein, Leu-M1, B72.3, factor XIIIa, and Le(x).