[Electron microscopic observation of hepato-cellular carcinoma in 15 cases--an ultrastructural comparison with human embryonic liver].

An ultrastructural comparison between 15 cases of hepatocellular carcinoma (HCC) and 5 cases of human embryonic liver (HEL) was performed. There were similarities. Both of them are polygonal in cell shape with a central nucleus and are abundant in RER and mitochondria; both have laminating form of RER and formation of bile capillary and perisinusoid space. These are important evidences for diagnosis of a tumor originating from hepatic cells. On the other hand, obvious differences were present between HCC and HEL. Cancer cells possess certain characteristics; they are pleomorphic and heterogeneitic; the differentiation of their ultrastructural components is not synchronic, and they are invasive in growth. These enable us to suspect the malignancy of a tumor. In addition, single death cancer cells with pyknotic nucleus were seen in HCC; some of them were phagocytozed by adjacent cells. We conside these are apoptosis even no formation of apoptoic bodies was found. In the majority of HCC cases, lymphocyte-mediated cancer cell lyses by both T-lymphocytes and large granular lymphocytes (nature killer cell) were found.