Rapidly progressive hepatocellular carcinoma mimicking benign portal vein thrombosis: a case report

A new and rare type of hepatocellular carcinoma: Survival and gene analysis of portal vein tumour thrombus-type hepatocellular carcinoma

BACKGROUND

Portal vein tumour thrombus (PVTT) in patients with hepatocellular carcinoma (HCC) is known as a major complication associated with poor survival. We clinically defined a new and rare type of HCC, PVTT-type HCC (PVTT-HCC), in a small group of HCC patients with HCC presenting only as PVTT without a demonstrable parenchyma tumour. The clinicopathological and biological features of PVTT-HCC are not clear.

METHODS

The data for patients who had PVTT-HCC with histologically confirmed HCC from January 2004 to December 2012 at the Eastern Hepatobiliary Surgery Hospital were retrospectively analysed. The survival outcomes of patients with PVTT-HCC were compared with those of HCC patients with PVTT (HCC-PVTT). Propensity score matching (PSM) analysis was performed to match patients at a ratio of 1:3. Then, we performed RNA-Seq analysis of liver samples from PVTT-HCC and HCC-PVTT patients to identify and compare differentially expressed genes and biological pathways between the two groups.

RESULTS

We observed and collected 10 rare cases of PVTT-HCC and performed a prospective cohort study to compare overall survival (OS) between PVTT-HCC and HCC-PVTT. PVTT invaded the main portal vein in 10 PVTT-HCC patients. Univariate and multivariate analyses demonstrated that ChildPugh (A/B), different treatments (LR/non-LR), and different groups were independent risk factors for OS. The median OS was 10.3 months (95 % CI = 6.7-13.8) in the HCC-PVTT group and 7.5 months (95 % CI = 2.8-12.1) in the PVTT-HCC group (P = 0.042). From RNA-Seq, 1630 differentially expressed genes were obtained, of which 731 were upregulated and 899 downregulated in PVTT-HCC compared with HCC-PVTT.

CONCLUSIONS

The survival outcomes of patients with PVTT-HCC were worse than those of patients with HCC-PVTT. RNA-Seq demonstrated differential gene expression between PVTT-HCC and HCC-PVTT, indicating that the former may have distinguishing biological characteristics and be a new and rare type of HCC.

A hypothesis on paradoxical privileged portal vein metastasis of hepatocellular carcinoma. Can organ evolution shed light on patterns of human pathology, and vice versa?

Unlike other carcinomas, hepatocellular carcinoma (HCC) metastasizes to distant organs relatively rarely. In contrast, it routinely metastasizes to liver vasculature/liver, affecting portal veins 3-10 times more often than hepatic veins. This portal metastatic predominance is traditionally rationalized within the model of a reverse portal flow, due to accompanying liver cirrhosis. However, this intuitive model is not coherent with facts: 1) reverse portal flow occurs in fewer than 10% of cirrhotic patients, while portal metastasis occurs in 30-100% of HCC cases, and 2) portal vein prevalence of HCC metastasis is also characteristic of HCC in non-cirrhotic livers. Therefore, we must assume that the route for HCC metastatic dissemination is the same as for other carcinomas: systemic dissemination via the draining vessel, i.e., via the hepatic vein. In this light, portal prevalence versus hepatic vein of HCC metastasis appears as a puzzling pattern, particularly in cases when portal HCC metastases have appeared as the sole manifestation of HCC. Considering that other GI carcinomas (colorectal, pancreatic, gastric and small bowel) invariably disseminate via portal vein, but very rarely form portal metastasis, portal prevalence of HCC metastasis appears as a paradox. However, nature does not contradict itself; it is rather our wrong assumptions that create paradoxes. The 'portal paradox' becomes a logical event within the hypothesis that the formation of the unique portal venous system preceded the appearance of liver in evolution of chordates. The analysis suggests that the appearance of the portal venous system, supplying hormones and growth factors of pancreatic family, which includes insulin, glucagon, somatostatin, and pancreatic polypeptide (HGFPF) to midgut diverticulum in the early evolution of chordates (in an Amphioxus-like ancestral animal), promoted differentiation of enterocytes into hepatocytes and their further evolution to the liver of vertebrates. These promotional-dependent interactions are conserved in the vertebrate lineage. I hypothesize that selective homing and proliferation of malignant hepatocytes (i.e., HCC cells) in the portal vein environment are due to a uniquely high concentration of HGFPF in portal blood. HGFPF are also necessary for liver function and renewal and are significantly extracted by hepatocytes from passing blood, creating a concentration gradient of HGFPF between the portal blood and hepatic vein outflow, making post-liver vasculature and remote organs less favorable spaces for HCC growth. It also suggested that the portal vein environment (i.e., HGFPF) promotes the differentiation of more aggressive HCC clones from already-seeded portal metastases, explaining the worse outcome of HCC with the portal metastatic pattern. The analysis also offers new hypothesis on the phylogenetic origin of the hepatic diverticulum of cephalochordates, with certain implications for the modeling of the chordate phylogeny.

Privileged portal metastasis of hepatocellular carcinoma in light of the coevolution of a visceral portal system and liver in the chordate lineage: a search for therapeutic targets

Hepatocellular carcinoma (HCC) disseminates systemically, but metastases occur in distant organs only in minority of patients, whereas HCC routinely metastasizes to liver and its vessels. HCC cells disseminate via hepatic veins, but portal veins are affected by metastasis more frequently than are hepatic veins, and correlates with poor prognosis. In this review, I suggest that privileged HCC portal metastasis occurs because of high levels of pancreatic family hormones and growth factors (PHGFs) in the portal blood. The analysis suggests that the appearance of the portal system carrying PHGFs in the evolution of invertebrate chordate (Amphioxus) led to the evolution of the liver in vertebrate; given that the portal pattern of HCC metastasis and selection of more-aggressive clones are PHGF dependent, PHGFs and their ligands constitute therapeutic targets.