Pathology of Hepatocellular Carcinoma

According to extensive studies on resected and biopsy materials of small hepatocellular carcinoma (HCC) of the early stage, a lot of new information about the morphologic characteristics of minute early-stage HCCs and the morphologic evolution of HCC from early to progressed stages have been obtained. Small HCC up to around 2 cm in size is categorized to two major types; distinctly and vaguely nodular type. Most of small HCC of distinctly nodular type are encapsulated and moderately differentiated, and are detected as hypervascular lesion. On the other hand, small HCC of vaguely nodular type is indistinctly nodular and well-differentiated, and contains portal tracts within the nodule and most of them are hypovascular. Despite small tumor size, the distinctly nodular type HCC is considered as progressed cancer but the vaguely nodular type is interpreted as an early HCC. Well-differentiated early HCCs are gradually de-differentiated and start to proliferate. Eventually, most of them become moderately differentiated when they reach to around 3 cm in size and show the clinicopathological features of classical HCC.