Best practices in diagnostic immunohistochemistry: hepatocellular carcinoma versus metastatic neoplasms.

Immunohistochemistry plays a crucial role in the diagnosis of hepatocellular carcinoma and in its distinction from other primary and metastatic neoplasms. Because limited tissue is available with fine-needle and core biopsies, appropriate selection of antibodies is imperative. To review the antibodies used for the diagnosis of hepatocellular carcinoma and to outline an immunohistochemical approach in commonly encountered clinical situations. Our experience and review of research articles published in the English literature between 1987 and 2006. Hep Par 1 and polyclonal carcinoembryonic antigen are the most reliable markers for hepatocellular differentiation, but they have low sensitivity for poorly differentiated cases. Immunohistochemistry for glypican-3 shows promise for the diagnosis of poorly differentiated hepatocellular carcinoma and for its distinction from benign processes such as hepatic adenoma. Further studies with a large number of cases are required before it can be widely used. The combination of Hep Par 1 and MOC-31 will allow for the diagnosis of hepatocellular carcinoma in most cases and will guide the selection of immunohistochemical markers for further workup.