Pathology of early hepatocellular carcinoma: progression from early to advanced.

Based on the pathomorphologic studies of resected hepatocellular carcinoma (HCC) and biopsy materials from minute HCCs of the early stage, it has been clarified that the majority of minute HCCs around 1 cm in diameter are well differentiated. When tumors reach approximately 2 cm in diameter, approximately one-third of them display various combinations of more than two cancerous tissues of different histologic grades. In those HCCs, the areas of less-differentiated cancerous tissues are almost always surrounded by well-differentiated ones and diminish in size along with the increase of tumor size. Then, they are completely replaced by moderately to poorly differentiated cancerous tissues. Dedifferentiation phenomenon characterized by such a replacement of well-differentiated cancerous tissues by less-differentiated ones seems to be closely related to tumor proliferation in HCC. Thus, better therapeutic effects may be expected if HCCs are treated while they are well differentiated and are less aggressive.