Hepatocellular carcinoma presenting as an incidental isolated malignant portal vein thrombosis.

INTRODUCTION: Portal vein thrombosis is frequently associated with hepatocellular carcinoma (HCC). Tumor invasion into the portal vein by direct venous extension or metastasis occurs in up to 70% of HCC patients (Cedrone et al., Liver 16:94-8, 1996). However, presentation as an isolated malignant portal vein thrombosis without any evidence of obvious hepatoma-like lesions in the liver by imaging studies is extremely uncommon. We present an unusual case of HCC presenting as a malignant portal vein thrombus, proven on biopsy of the thrombus without any evidence of primary liver lesion. This, to our knowledge, is the first case of HCC presenting as an incidental isolated malignant portal vein thrombosis. The importance of doing delayed enhancement imaging studies to rule out malignant portal vein thrombosis is emphasized. CASE REPORT: A 60-year-old man presented with acute substernal chest pain. Physical examination revealed icterus. Examination of the abdomen did not reveal any organomegaly. Liver function test revealed a predominantly conjugated bilirubinemia. Abdominal sonogram revealed thrombosis and occlusion of the posterior right portal vein. Liver parenchyma was homogenous with no intrahepatic mass. Computed tomography (CT) of the abdomen and pelvis after administration of oral and intravenous contrast with delayed views revealed arterial enhancement of the right portal vein thrombus with delayed washout. MRI of the abdomen with gadolinium confirmed the right portal vein thrombus without focal hepatic mass. Aspiration of the right portal vein thrombus under CT guidance revealed hepatocellular carcinoma which was confirmed by immunohistochemistry. Serum alpha-fetoprotein level was very high. Patient was started on sorafenib with subsequent decrease in alpha-fetoprotein level. He was doing well till the date of this report. DISCUSSION: This unusual case of hepatocellular carcinoma presenting as an incidental malignant portal vein thrombosis without any primary liver lesion is extremely rare. Other reported cases of malignant portal vein thrombosis have been in patients with underlying hepatoma, cirrhosis, or with intrabiliary hepatocelluar carcinoma. In the clinical setting of portal vein thrombosis, imaging studies showing enhancement of the thrombus in the arterial phase are important in leading to the diagnosis of malignancy.