Histomorphological Subtypes of Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma: Review and Update

Primary liver cancers comprise a heterogeneous group of neoplasms, with the 2 main entities being hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Over the past decades, HCC and iCCA have been recognized to be heterogeneous in morphology, molecular features, and biological behavior, and the most recent World Health Organization classification of digestive system tumors describes various histomorphological subtypes of HCC and iCCA, some of which also have characteristic molecular features, clinical correlates, and prognostic implications. In this review, we discuss 4 recently described subtypes of HCC and iCCA—macrotrabecular HCC, steatohepatitic HCC, scirrhous HCC, and small duct iCCA—based on a series of cases.