Histological Mimicker of Hepatocellular Carcinoma in the Liver

Abstract

Hepatocellular carcinoma (HCC) is a common malignancy worldwide and the second most common fatal cancer in China and Southeast Asia. Introduction of new treatment modalities including targeted therapy may hopefully bring better survival of patients. A precise pathological diagnosis of HCC is crucial in view of the prognostic and treatment implications. The characteristic histology of HCC can be identified in most cases, yet histological mimickers and poorly differentiated tumors impose diagnostic challenges from time to time. The appropriate use of immunohistochemical markers and cautious interpretation of results are essential in difficult scenarios. Markers such as CD10, polyclonal carcinoembryonic antigen, HepPar-1, and the recently reported arginase 1 are helpful in confirming the hepatocytic differentiation of a malignant liver tumor. Glypican 3, either singly or in combination with glutamine synthetase and heat shock protein 70, is useful in distinguishing HCC from precursor lesions. Immunoexpression of CK19 may signify hepatic progenitor cell phenotype of HCCs. Application of specific immunohistochemical markers for other cell lineages would also help to confirm a diagnosis of liver metastasis. Clinicopathological correlation remains indispensible in pathological diagnosis.