Department of Pathology, Yale University, New Haven, CT.
Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor seen in adults. The histopathologic diagnosis of classic or conventional differentiated HCC is seldom challenging, however, HCC is a particularly heterogenous tumor. HCC often has a medley of morphologic features that are either challenging to recognize as hepatocellular, or represents components that are of complex histogenesis. This review focuses on the heterogenous nature of HCC, with discussion of the histologic variants, some of which the clinical significance is unknown. In some cases, a lack of numbers precludes elucidating the clinical significance of these variants. Ultimately, larger studies are needed to determine the diagnostic and prognostic relevance of the phantasmagoria within HCC.