Tumor thrombus in the branches of the distal portal vein: CT demonstration.

Punctate and linear low density structures adjacent to the tumor nodules in the CT images of eight patients with hepatocellular carcinomas were followed for greater than 5 months to investigate the evolution of these low density structures. During the period of follow-up, patients were given anticancer therapy. Computed tomographic, angiographic, and autopsy examinations indicated that the CT finding of punctate or linear low density structures represented a tumor thrombus in the portal branches of the third and more distal orders. In two cases that showed punctate or linear low density structures adjacent to the distal side of the tumor nodules to the porta hepatis, a daughter nodule was detected by CT at 6.5 and 9.2 months, respectively, after the appearance of the low density structures. In two cases that showed punctate or linear low density structures adjacent to the proximal side of the tumor nodules to the porta hepatis, rapid and extensive tumor growth was found by CT at 5.4 and 8.0 months, respectively, after the appearance of the low density structures.