Christine Sempoux

Hepatocellular adenoma: Classification, variants and clinical relevance

Hepatocellular adenomas are benign tumors with two major complications, bleeding and malignant transformation. The overall narrative of hepatocellular adenoma has evolved over time. Solitary or multiple hepatocellular developing in the normal liver of women of child bearing age exposed to oral contraceptives still represents the most frequent clinical context, however, new associations are being recognized. Hepatocellular adenoma is discovered on a background of liver diseases such as non-alcoholic steatohepatitis, vascular diseases, and alcoholic cirrhosis. Hepatocellular adenoma is also reported in men, young or older adults, and even in infants. On the morpho-molecular side, the great leap forward was the discovery that hepatocellular adenoma was not a single entity and that at least 3 different subtypes exist, with specific underlying gene mutations. These mutations affect the HNF1A gene, several genes leading to JAK/STAT3 pathway activation and the CTNNB1 gene. All of them are associated with more or less specific histopathological characteristics and can be recognized using immunohistochemistry either with specific antibodies or with surrogate markers. Liver pathologists and radiologists are the key actors in the identification of the different subtypes of hepatocellular adenoma by the recognition of their specific morphological features. The major impact of the classification of hepatocellular adenoma is to identify subjects who are at higher risk of malignant transformation. With the development of new molecular technologies, there is hope for a better understanding of the natural history of the different subtypes, and, particularly for their mechanisms of malignant transformation.

Visualization of hepatitis E virus RNA and proteins in the human liver

BACKGROUND & AIMS Although hepatitis E constitutes a substantial disease burden worldwide, surprisingly little is known about the localization of hepatitis E virus (HEV) in the human liver. We therefore aimed to visualize HEV RNA and proteins in situ. METHODS A panel of 12 different antibodies against HEV open reading frame (ORF) 1-3 proteins was evaluated for immunohistochemistry (IHC) and two probes for in situ hybridization (ISH) in formalin-fixed, paraffin-embedded (FFPE) HuH7 cells transfected with HEV ORF1-3 expression vectors. IHC (and partly ISH) were then applied to Hep293TT cells replicating infectious HEV and liver specimens from patients with hepatitis E (n=20) and controls (n=134). RESULTS Whereas ORF1-3 proteins were all detectable in transfected, HEV protein-expressing cells, only ORF2 and 3 proteins were traceable in cells replicating infectious HEV. Only the ORF2-encoded capsid protein was also unequivocally detectable in liver specimens from patients with hepatitis E. IHC for ORF2 protein revealed a patchy expression in individual or grouped hepatocytes, generally stronger in chronic compared to acute hepatitis. Besides cytoplasmic and canalicular, ORF2 protein also displayed a hitherto unknown nuclear localization. Positivity for ORF2 protein in defined areas correlated with HEV RNA detection by ISH. IHC was specific and comparably sensitive as PCR for HEV RNA. CONCLUSIONS ORF2 protein can be reliably visualized in the liver of patients with hepatitis E, allowing for sensitive and specific detection of HEV in FFPE samples. Its variable subcellular distribution in individual hepatocytes of the same liver suggests a redistribution of ORF2 protein during infection and interaction with nuclear components. LAY SUMMARY The open reading frame (ORF) 2 protein can be used to visualize the hepatitis E virus (HEV) in the human liver. This enabled us to discover a hitherto unknown localization of the HEV ORF2 protein in the nucleus of hepatocytes and to develop a test for rapid histopathologic diagnosis of hepatitis E, the most common cause of acute hepatitis worldwide.

cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation

Primary liver carcinomas with both hepatocytic and cholangiocytic differentiation have been referred to as “combined (or mixed) hepatocellular‐cholangiocarcinoma.” These tumors, although described over 100 years ago, have attracted greater attention recently because of interest in possible stem cell origin and perhaps because of greater frequency and clinical recognition. Currently, because of a lack of common terminology in the literature, effective treatment and predictable outcome data have been challenging to accrue. This article represents a consensus document from an international community of pathologists, radiologists, and clinicians who have studied and reported on these tumors and recommends a working terminology for diagnostic and research approaches for further study and evaluation. Conclusion: It is recommended that diagnosis is based on routine histopathology with hematoxylin and eosin (H&E); immunostains are supportive, but not essential for diagnosis. (Hepatology 2018;68:113‐126).

Malignant transformation of a β-catenin inflammatory adenoma due to an S45 β-catenin–activating mutation present 12 years before

In 1984, a 24-year-old woman underwent a right hepatectomy after a 17-cm nodule, diagnosed as a hepatocellular adenoma with some atypia. The resection was incomplete. Follow-up was interrupted. In 1996, a computed tomographic scan revealed a large multifocal hepatocellular carcinoma confirmed on biopsies. The patient died the same year. We reviewed these nodules using immunohistochemistry and gene sequencing. C-reactive protein was overexpressed in the tumor resected in 1984. Glutamine synthetase was heterogeneous in the tumor, with a few tumor nuclei expressing β-catenin. Glypican and heat shock protein 70 were negative. In this β-catenin-activated inflammatory hepatocellular adenoma, S45 β-catenin-activating mutation was detected on fixed tissue, embedded in paraffin without TERT promoter mutation. An identical CTNNB1 mutation was identified in the 1996 liver tumor together with a TERT promoter mutation showing that this hepatocellular carcinoma results from the malignant transformation of the initial β-catenin inflammatory adenoma.

Expression of Molecular Differentiation Markers Does Not Correlate with Histological Differentiation Grade in Intrahepatic Cholangiocarcinoma

The differentiation status of tumor cells, defined by histomorphological criteria, is a prognostic factor for survival of patients affected with intrahepatic cholangiocarcinoma (ICC). To strengthen the value of morphological differentiation criteria, we wished to correlate histopathological differentiation grade with expression of molecular biliary differentiation markers and of microRNAs previously shown to be dysregulated in ICC. We analysed a series of tumors that were histologically classified as well, moderately or poorly differentiated, and investigated the expression of cytokeratin 7, 19 and 903 (CK7, CK19, CK903), SRY-related HMG box transcription factors 4 and 9 (SOX4, SOX9), osteopontin (OPN), Hepatocyte Nuclear Factor-1 beta (HNF1β), Yes-associated protein (YAP), Epithelial cell adhesion molecule (EPCAM), Mucin 1 (MUC1) and N-cadherin (NCAD) by qRT-PCR and immunostaining, and of miR-31, miR-135b, miR-132, miR-200c, miR-221 and miR-222. Unexpectedly, except for subcellular location of SOX9 and OPN, no correlation was found between the expression levels of these molecular markers and histopathological differentiation grade. Therefore, our data point toward necessary caution when investigating the evolution and prognosis of ICC on the basis of cell differentiation criteria.

Focal β-catenin mutation identified on formalin-fixed and paraffin-embedded inflammatory hepatocellular adenomas

The identification of hepatocellular adenoma (HCA) with mutation in exon 3 of the CTNNB1 gene encoding for β‐catenin is clinically relevant due to a higher risk of malignant transformation. Inflammatory HCA (IHCA) can exhibit β‐catenin activation (β‐IHCA). We report two cases with multiple IHCA in which focal β‐catenin activation has been found in one of the IHCA. In both cases, the diagnosis of IHCA was confirmed on the resected nodules by routine stains, immunohistochemical detection of C‐reactive protein (CRP) and molecular biology on frozen material. An additional molecular analysis was performed on formalin‐fixed paraffin‐embedded (FFPE) material that showed focal glutamine synthetase (GS) staining, the surrogate marker of β‐catenin activation. In case 1, it was a 1.8‐cm area within the 7.5 cm IHCA, and in case 2 a small 0.3‐cm area within a 1.8 cm resected IHCA located close to a larger IHCA, negative for GS. In both cases, nuclear β‐catenin expression and decreased reticulin network were observed in the GS expressing foci, together with cholestasis and diffuse CD34 expression in case 1. Molecular analysis by pyrosequencing on FFPE material using the GS‐stained slides as reference to select areas with/without positive staining revealed a CTNNB1 exon 3 mutation restricted to the areas exhibiting both positive GS and CRP expression, whereas wild‐type CTNNB1 was found in areas showing only CRP staining. These two cases illustrate focal β‐catenin activation that can occur within IHCAs. Additional data are needed to determine if β‐catenin mutation is a secondary event in IHCA.

Local recurrence rate in patients with colorectal cancer liver metastasis after wedge resection or percutaneous radiofrequency ablation.

Abstract Purpose: To compare local recurrence (LR) rate in patients with colorectal cancer liver metastasis (CRCLM) after surgical wedge resection (WR) or radiofrequency ablation (RFA) and to investigate predictive factors of LR. Materials and methods: This single-centre, retrospective, institutional review board-approved study including 43 consecutive patients with 121 metastases treated by WR and 60 patients with 110 metastases treated by RFA between 2007 and 2014 with 23 and 18.5 months of follow-up, respectively. Demographics and tumour characteristics were compared using the unpaired t-test and chi-square test. Predictive factors for LR (lesion size, depth, relation to hepatic vessels, intervention, margin status) were investigated in uni- and multivariate analyses. Results: Patient and CRCLM characteristics were similar in both groups. Mean lesion size and depth in the WR and RFA groups were 18 mm and 15 mm (p = 0.03), and 19 mm and 26 mm (p < 0.001), respectively. LR showed a trend towards difference in favour of RFA (19% and 10% in the WR and RFA groups, respectively, p = 0.06). Positive margins and lesion depth were predictive factors of LR in the WR group (p = 0.03 and p = 0.02, respectively, on uni- and multivariable analyses). Lesion depth and proximity to a vein increased the risk of positive margins on pathology after WR (p = 0.04 and p < 0.001, respectively). Our analysis did not identify any predictive factors of LR following RFA. Conclusion: Our study showed a trend towards a lower LR rate with RFA compared to WR. Lesions located deep in the liver and/or close to large vessels are at high risk of LR following WR, while curative treatment can be obtained with RFA.

Variant differentiation patterns in primary liver carcinoma

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma are two distinct forms of primary liver carcinoma recognizable at the microscope by their architectural and cytological characteristics, as well as specific immunohistochemical profiles. This straightforward concept however, is increasing imperiled by the recognition of primary liver carcinomas that do not subscribe to a dichotomous paradigm of differentiation, and instead demonstrate biphenotypic differentiation, stem/progenitor cell like features or other variant patterns of differentiation. Appropriate nomenclature, diagnostic criteria, prognostic significance and optimal therapeutic approach for these variant tumors are not completely defined, not leasyt because they are not always identified correctly and when they are, lack of uniform terminology hinders collection of adequate number of cases to facilitate their study. Similar to hepatocellular carcinoma and in contrast with intrahepatic cholangiocarcinoma, primary liver tumors showing biphenotypic differentiation, stem/progenitor cell features or variant differentiation occur mainly, but not always, on a background of chronic liver disease. They are particularly frequent after neo-adjuvant therapy. Whether they represent trans-differentiation of malignant cells, or whether they derive from a stem/progenitor cell that gives rise to divergent differentiation remains yet another area of uncertainty.

Sterilization of tumor-positive lymph nodes of esophageal cancer by neo-adjuvant treatment is associated with worse survival compared to tumor-negative lymph nodes treated with surgery first

Lymph node (LN) involvement by esophageal cancer is associated with compromised long‐term prognosis. This study assessed whether LN downstaging by neoadjuvant treatment (NAT) might offer a survival benefit compared to patients with a priori negative LN.

Hepatocellular Adenomas: Morphology and Genomics

Hepatocellular adenomas (HCAs) are rare benign tumors. This single entity has been split into 3 subtypes corresponding to specific mutations: HNF1α-inactivated HCA; inflammatory HCA related to different mutations, all leading to activation of STAT3 pathway; and β-catenin-activated HCA related to CTNNB1 mutations. The risk of malignant transformation depends on the level of β-catenin activation, reported mainly for exon 3, including S45. It is possible using specific immunohistochemical markers to identify the 3 different HCA subtypes and the level of β-catenin activation. Fewer than 10% of HCAs remain unclassified.