Pathobiological and radiomic approach for hepatocellular carcinoma subclassification

Introduction: The classic histopathological features of hepatocellular carcinoma (HCC) are still inadequate in determining patient’s prognosis. Aims: (i) To improve HCC classification, including a better definition of advanced HCCs, with amultidisciplinary approach Beyond morphology; (ii) to identify the radiological features distinctive of the “histologically-advanced” HCCs. Materials and methods: Histopathological analysis, immunohistochemistry for CD34 and Nestin, and reverse transcriptasepolymerase chain reaction (RT-PCR) for TGF1 and IGF1R mRNA were performed on 96 HCCs for the identification of different morpho-vascular patterns; 740 miRNAs were analyzed on 22 HCCs by means of microfluidic cards; histopathological and magnetic resonance imaging (MRI) data of 39 liver nodules were correlated. Results: Four distinct morpho-vascular HCC patterns had been identified at pathology: (A) microtrabecular with CD34-positive Nestin-negative sinusoids; (B) microtrabecular with CD34-positive Nestin-positive sinusoids; (C) with macrotrabeculae covered by CD34-positive Nestin-positive endothelium; (D) solid HCCs with CD34-positive Nestin-positive new-formed arteries. At RT-PCR a significant increase in TGF1 and IGF1R mRNA was found between pattern A and the other patterns. Moreover, each pattern correlated with a peculiar miRNA expressions. On MRI, pattern A HCCs were isointense in 50% of cases on T1-weighted images (WI) and in 57% on T2-WI. Pattern B HCCs were hyperintense on T1-WI in two-third of cases, radiological features of “glycogen nodules”, without hyperintensity on T2-WI. Pattern D HCCs were isointense on T1-WI in 83% of cases and hyperintense on T2-WI in 50%, all detected by typical vascular pattern on MRI. Pattern C HCCs showed the highest heterogeneity. Conclusions: Our multidisciplinary approach allowed us to identify different morphological and vascular HCC types, each of them characterized by different expression of growth factors and miRNAs, and with peculiar MRI features too. While pattern A HCCs represent the “early” phase of hepatocarcinogenesis, pattern D could be recognized as advanced malignancies that skip the regenerative-dysplastic-neoplastic pathway