Portal venous tumor growth-type of hepatocellular carcinoma without liver parenchyma tumor nodules: a case report.

The patient was a 43-year-old man with chronic hepatitis B without history of hepatocellular carcinoma (HCC), who was first diagnosed with thrombosis in right portal vein trunk and portal vein branches and ruptured esophageal varices in October 2011. He underwent endoscopic variceal ligation, but ruptured repeatedly. Despite anti-coagulant therapy, the thrombosis expanded from right portal vein trunk to upper mesenteric vein in March 2012. Computed tomography (CT) scan showed that portal vein thrombosis had low density from early to late phase. No focal liver lesions were identified by CT scan or ultrasound, and alpha-fetoprotein (AFP) was within normal range. He died by intractable esophageal variceal bleeding in April 2012. Pathological examination of autopsy specimen showed that portal vein thrombosis was consistent with poorly-differentiated HCC. The portal vein tumor thrombosis (PVTT) had only a few tumor vessels, which were compressed by fibromatous change originating from HCC formation, so were represented as low-density lesions from arterial to portal phase of CT. In addition, PVTT was negative for AFP, so representing serum value of AFP within normal range. PVTT had positive staining for c-kit, which is a liver stem cell marker. Liver tumors in the whole liver parenchyma were not found pathologically. PVTT might have the characteristics of presumed liver cancer stem cells. We experienced the first case of HCC only in portal vein without liver parenchyma tumor nodules, with difficult differential diagnosis from a non-malignant portal vein thrombosis. We also reported new tumor profiles of the portal venous tumor growth- type of HCC.