Evaluation of hepatocellular neoplasms in mice.

Thirty C3H-AvyfB male mice from 3 to 15 months of age were killed, and the genesis of their hepatocellular neoplasms was studied. As the mice aged, the number of tumors per liver and mean diameter of the tumors increased. Histologically, the smallest tumors were composed of solid sheets of cells and were better differentiated than the largest tumors. Small foci of hepatocytes in prominent trabeculae formation was a common characteristic of large tumors. In addition, 18 metastatic hepatocellular carcinomas observed in aged C3H-AvyfB, C3HfC, C3H, C3HfB, (C3HfB x YBR)F1, or C57BL/6 mice were also included for a morphologic study of their primary and metastatic lesions. Invariably, the pulmonary metastases were composed of a well-differentiated sheet of hepatocytes that resembled those in the solid liver tumors. The smallest hepatocellular neoplasms appear to represent early stages in the development of metastatic hepatocellular carcinoma.