Teaching Case

A patient with treated hepatocellular carcinoma with chemoembolisation underwent CT examination which detected an enhancing nodule within the lesion with concomitant portal vein thrombosis.

The patient patient, who had a history of chronic HCV-related liver disease, presented because of a 4cm hepatocellular carcinoma (HCC) previously treated with chemioembolisation. On his previous blood exams, alpha-fetoprotein (alpha-FP) and gamma-glutamyl-transpeptidase (gamma-GT) were strongly increased.

He, therefore, underwent spiral contrast-enhanced CT (Fig. 1) which detected findings compatible with residual viable tissue within the treated lesion. In addition, the mass infiltrated the right portal branch and the main trunk (Fig. 2).

Portal vein thrombosis mostly occurs in patients with cirrhosis because of portal hypertension and venous stasis, whereas malignant thrombosis is usually secondary to direct invasion of the portal vein by hepatocellular carcinoma (HCC). Portal vein thrombosis may develop also after percutaneous procedures resulting in intravascular spread of residual or recurrent malignancy, or endothelial cell injury caused by ethanol vessels neighbouring the tumour. Moreover up to 20% of patients with Budd-Chiari syndrome can have concomitant portal venous thrombosis. The initial thrombus could cause total obstruction of the portal vein and, as it organises, flow is restored in the portal vein. Collateral flow rapidly develops and there is hepatic arterial dilatation following portal venous obstruction. Accurate knowledge of the nature of the portal vein is crucial for the appropriate management of these patients. Although several reports have been published about the diagnostic evaluation of portal vein thrombosis, little information exists about the characteristics that allow differentiation between benign and malignant thrombi.

Recent studies suggested that colour Doppler US is valuable in the differential diagnosis of portal vein thrombosis, by detecting pulsatile flow within the thrombus, even if the reported sensitivity and specificity vary considerably. On CT scan the acute thrombus is seen as a high attenuation mass without contrast enhancement; meanwhile, if it is due to tumour invasion from hepatocellular carcinoma, the thrombus enhances with intravenous contrast medium, thus showing the same appearance as the primary tumour.