MORPHOLOGICAL-STUDY OF VASCULAR DISSEMINATION IN A METASTATIC HEPATOCELLULAR-CARCINOMA MODEL IN THE MONKEY

In this report we describe a metastatic monkey hepatocellular carcinom a (HCC) model in which intravascular metastatic development is clearly evident, The tumor-bearing livers contained intravenous tumor thrombi at different stages of progression within the small branches of the p ortal vein. These ranged from mural tumor thrombi lined with CD31-posi tive endothelial cells to tumor thrombi that had completely occluded t he vascular lumen, Intravenous tumor expansion was frequently accompan ied by the appearance of CD31-positive microvessels within the tumor t hrombi and fibrous perivascular thickening, giving rise to isolated tu mor nodules within the portal areas, Intravascular expansion of dissem inating HCC was also evident within small branches of the pulmonary ar teries in the lungs, These findings indicate that metastases of HCC ca n become established while still at an intravascular stage, suggesting that the direct interaction between tumor cells and parenchymal cells predicted from experimental rodent metastasis models is not a prerequ isite for the metastatic development of these tumors.