Proteomic Profiling of Hepatocellular Adenomas Paves the Way to Diagnostic and Prognostic Approaches.

BACKGROUND AND AIMS: Through an exploratory proteomic approach based on typical hepatocellular adenomas (HCAs), we previously identified a diagnostic biomarker for a distinctive subtype of HCA with high risk of bleeding, already validated on a multicenter cohort. We hypothesized that the whole protein expression deregulation profile could deliver much more informative data for tumor characterization. Therefore, we pursued our analysis with the characterization of HCA proteomic profiles, evaluating their correspondence with the established genotype/phenotype classification and assessing whether they could provide added diagnosis and prognosis values. APPROACH AND RESULTS: From a collection of 260 cases, we selected 52 typical cases of all different subgroups on which we built a reference HCA proteomics database. Combining laser microdissection and mass-spectrometry-based proteomic analysis, we compared the relative protein abundances between tumoral (T) and nontumoral (NT) liver tissues from each patient and we defined a specific proteomic profile of each of the HCA subgroups. Next, we built a matching algorithm comparing the proteomic profile extracted from a patient with our reference HCA database. Proteomic profiles allowed HCA classification and made diagnosis possible, even for complex cases with immunohistological or genomic analysis that did not lead to a formal conclusion. Despite a well-established pathomolecular classification, clinical practices have not substantially changed and the HCA management link to the assessment of the malignant transformation risk remains delicate for many surgeons. That is why we also identified and validated a proteomic profile that would directly evaluate malignant transformation risk regardless of HCA subtype. CONCLUSIONS: This work proposes a proteomic-based machine learning tool, operational on fixed biopsies, that can improve diagnosis and prognosis and therefore patient management for HCAs.

Hepatocellular adenomas in the Turkish population: reclassification according to updated World Health Organization criteria.

AIMS: Hepatocellular adenoma (HCA) is an uncommon liver neoplasm, and studies of HCA subtypes have been primarily limited to France, the USA, and Japan. The aim of this study was to describe the clinicopathological features of HCA subtypes in Turkey. METHODS AND RESULTS: The resection specimens of 59 cases diagnosed as 'hepatocellular adenoma' collected from 15 institutions were reviewed to confirm the diagnosis and to classify them according to the current World Health Organization 2019 classification. Immunostaining for glutamine synthetase, liver fatty acid-binding protein, C-reactive protein, ß-catenin and reticulin was performed. Of the 59 cases, 48 (81%) were diagnosed as HCA. We identified 24 (50%) hepatocyte nuclear factor 1α (HNF1α)-inactivated HCAs, five (10%) inflammatory HCAs, 15 (32%) ß-catenin-activated HCAs, three (6%) ß-catenin-activated inflammatory HCAs, and one (2%) unclassified HCA. HCA patients were predominantly female (female/male ratio of 5:1); they had a median age of 34 years and a median tumour diameter of 60 mm. In the ß-catenin-activated HCA group, nine cases (19%) showed cytoarchitectural atypia, and were also referred to as atypical hepatocellular neoplasms. In the ß-catenin-activated HCA group, three cases (6%) showed focal areas supportive of transition to HCA. The original diagnosis of HCA was changed to well-differentiated hepatocellular carcinoma in nine cases and to focal nodular hyperplasia in two cases. CONCLUSION: In our series, the major HCA subtype was HNF1α-inactivated HCA. We found a low incidence of inflammatory-type HCA. Our data also showed that ß-catenin-activated hepatocellular neoplasms, including cases with atypical histology, constituted a relatively high proportion of the cases. These findings are in contrast to those of most other studies of HCA subtypes.

Analysis of contrast-enhanced ultrasound features of hepatocellular adenoma according to different pathological molecular classifications.

OBJECTIVE: To explore the specific contrast-enhanced ultrasound (CEUS) features of hepatocellular adenomas (HCA) according to their pathological molecular classifications. METHODS & MATERIALS: In this retrospective study, fifty-three histopathologically proved HCA lesions (mean size, 39.7±24.9 mm) were included. Final histopathological diagnosis of HCA lesions were identified by surgical resection (n = 51) or biopsy (n = 2) specimens. CEUS imaging features were compared among four subgroups according to World Health Organization (WHO) 2019 pathological molecular classifications standards. Analysis of variance (ANOVA) were used for statistical analysis of continuous variables. Fisher's exact test were used for categorical variables. The sensitivity (SE), specificity (SP), and accuracy of CEUS feature in diagnosis of each HCA subtype were calculated and compared. RESULTS: Final histopathological diagnosis included HNF-1α inactivated HCAs (H-HCA, n = 12), ß-catenin activated HCAs (B-HCA, n = 8), inflammatory HCAs (I-HCA, n = 31), and unclassified HCAs (U-HCA, n = 2). During arterial phase of CEUS, all HCAs were hyper-enhanced, 66.6% (8/12) of H-HCAs and 50% (4/8) of B-HCAs displayed complete hyperenhancement, whereas 58.0% (18/31) of I-HCAs showed centripetal filling hyperenhancement pattern (P = 0.016). Hyper-enhanced subcapsular arteries could be detected in 64.5% (20/31) I-HCAs during early arterial phase. During portal venous and late phase, sustained hyper- or iso-enhancement were observed in 91.7% (11/12) of H-HCAs, while most of I-HCAs (61.3%, 19/31) and B-HCAs (7/8, 87.5%) were hypo-enhanced (P = 0.000). Central unenhanced areas were most commonly observed in I-HCAs (29.0%, 9/31) (P = 0.034). CONCLUSION: Depending on its unique imaging features including enhancement filling pattern, hyper-enhanced subcapsular artery and presence of washout, CEUS might provide helpful diagnostic information for preoperative prediction of various HCA molecular subtypes.

Development and Validation of a Model to Predict Regression of Large Size Hepatocellular Adenoma.

INTRODUCTION: Surgery is advocated in hepatocellular adenomas (HCA) >5 cm that do not regress to <5 cm after 6-12 months. The aim of this study was to develop a model for these patients, estimating the probability of HCA regression to <5 cm at 1 and 2 years follow-up. METHODS: Data were derived from a multicenter retrospective cohort of female patients diagnosed with HCA >5 cm at first follow-up. Potential predictors included age, body mass index, and HCA diameter at diagnosis (T0), HCA-subtype (hepatocyte nuclear factor 1α inactivated HCA, inflammatory-HCA, unclassified HCA) and "T0-T1 regression-over-time" (percentage of regression between T0 and first follow-up (T1) divided by weeks between T0 and T1). Cox proportional hazards regression was used to develop a multivariable model with time to regression of HCA < 5 cm as outcome. Probabilities at 1 and 2 years follow-up were calculated. RESULTS: In total, 180 female patients were included. Median HCA diameter at T0 was 82.0 mm and at T1 65.0 mm. Eighty-one patients (45%) reached the clinical endpoint of regression to <5 cm after a median of 34 months. No complications occurred during follow-up. In multivariable analysis, the strongest predictors for regression to <5 cm were HCA diameter at T0 (logtransformed, hazard ratio (HR) 0.05), T0-T1 regression-over-time (HR 2.15) and HCA subtype inflammatory-HCA (HR 2.93) and unclassified HCA (HR 2.40), compared to hepatocyte nuclear factor 1α inactivated HCA (reference). The model yielded an internally validated c-index of 0.79. DISCUSSION: In patients diagnosed with HCA > 5 cm that still exceed 5 cm at first follow-up, regression to <5 cm can be predicted at 1 and 2 years follow-up using this model. Although external validation in an independent population is required, this model may aid in decision-making and potentially avoid unnecessary surgery.

New MRI features improve subtype classification of hepatocellular adenoma.

OBJECTIVE: MRI is crucial for the classification of hepatocellular adenomas (HCA) into subtypes. Our objective was to review and increase MRI criteria for subtype classification and define the limits. METHODS: Pathological and radiological data of 116 HCAs were retrospectively analyzed to investigate MRI features of HCA pathological subtypes. Risk for complication was also evaluated with regard to subtype and tumor size. RESULTS: 38/43 (88%) HNF1α-mutated HCAs (H-HCAs) were discriminated by (i) fatty component (homogeneous or heterogeneous) and (ii) hypovascular pattern, with a sensitivity of 88% and a specificity of 97%. 51/58 (88%) inflammatory HCAs (IHCAs) displayed features of sinusoidal dilatation (SD) including three different patterns (global SD, atoll sign, and a new "crescent sign" corresponding to a partial peripheral rim, hyperintense on T2W and/or arterial phase with persistent delayed enhancement). Sensitivity was 88% and specificity 100%. However, some HCA remained unclassifiable by MRI: HCA remodeled by necrotic/hemorrhagic changes covering > 50% of the lesion, H-HCAs without steatosis, IHCAs without SD, ß-catenin-mutated and unclassified HCAs. Regarding malignant transformation (5/116) and bleeding (24/116), none was observed when the HCA diameter was smaller than 5.2 cm and 4.2 cm, respectively. CONCLUSION: Based on the largest series evaluated until now, we identified several non-described MRI features and propose new highly sensitive and specific MRI criteria. With the addition of these new features, 88% of the two main HCA subtypes could be identified. KEY POINTS: • HNF1α-mutated hepatocellular adenomas (H-HCA) are characterized by the presence of fat and hypovascular pattern in MRI. • Inflammatory hepatocellular adenomas (I-HCA) are characterized by different patterns translating sinusoidal dilatation including the newly described crescent sign. • No MRI specific pattern was identified for ß-catenin-mutated HCA (b-HCA).

Snapshot summary of diagnosis and management of hepatocellular adenoma subtypes.

Hepatocellular adenomas (HCA) are rare benign hepatocellular tumors occurring mainly in women taking oral contraceptives with 2 major complications: severe bleeding and malignant transformation that can be avoided if nodules exceeding 5 cm are resected. This simple attitude has been challenged in the recent years with HCA in men, in young adolescent, in aged persons, and complications in hepatocellular adenomas below 5 cm. The discovery of specific mutations leading to specific phenotypes has modified the clinical spectrum of the disease. The phenotypic immune classification of HCA based on the molecular classification is being widely used in liver referral centers. The aim of this snapshot is to briefly present for each subtype the clinical, pathological, immuno-pathological criteria as well as the risk of complications and guidelines for treatment and management.

Ultrasound Imaging of Hepatocellular Adenoma Using the New Histology Classification.

Hepatocellular adenoma is a rare benign liver tumor. Predisposing factors include hepatic storage diseases and some genetic conditions. A new histology-based classification has been proposed but to date, the corresponding ultrasound imaging features have not been reported. Here we review the new classification scheme and discuss the corresponding features on contrast-enhanced ultrasound imaging.

Subclassification of hepatocellular adenomas: practical considerations in the implementation of the Bordeaux criteria.

Hepatocellular adenomas are benign liver lesions with a risk of rupture and malignant transformation. Various molecular subgroups have been identified which appear to have characteristic morphological and immunohistochemical features. We examined the morphology and immunohistochemical profile of a series of 121 HCA from 97 patients to identify the HCA subtypes present and determine the number at risk for malignant transformation according to the World Health Organization (WHO) criteria for hepatocellular adenomas. There were 34 HNF1α inactivated HCA (28%), 61 inflammatory HCA (50%), 15 ß-catenin activated HCA (12%) and 11 unclassified adenomas (9%). This proportion of cases was similar to that seen in other series utilising molecular classification. The morphological features of the adenomas were suggestive but not definite indicators of the subtypes present. Morphological features that showed overlap between the subtypes included steatosis within the lesion, a ductular reaction and focal atypia, so that immunohistochemical typing was required for accurate classification. In conclusion, immunohistochemistry is a clinically useful surrogate for identifying underlying molecular changes in the HCA subtypes.

Hepatic Adenomas: Classification, Controversies, and Consensus.

Rapid advances in molecular and anatomic pathology have greatly improved our understanding of hepatocellular adenomas. Principle among them is a clinically relevant, histology-based classification that identifies hepatic adenomas at greatest risk for malignant transformation. This new classification system has led to general consensus on the major subtypes of hepatic adenomas. However, controversy remains regarding how to incorporate less common types of hepatic adenomas into the classification system and how to incorporate adenoma subtyping into clinical care. This article provides an in-depth review of how adenomas are classified, with a focus on the current rationale, the consensus, and controversies.

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 ß-catenin-activated HCA related to CTNNB1 mutations. The risk of malignant transformation depends on the level of ß-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 ß-catenin activation. Fewer than 10% of HCAs remain unclassified.

A Limited Immunohistochemical Panel Can Subtype Hepatocellular Adenomas for Routine Practice.

OBJECTIVES: ß-Catenin-activated hepatocellular adenomas have an elevated risk of harboring foci of hepatocellular carcinoma. Inflammatory adenomas also have an increased propensity for malignant transformation and are associated with a systemic inflammatory syndrome. Patients with these two adenoma subtypes benefit from excision. We assessed whether ß-catenin-activated and inflammatory adenomas could be identified using a limited immunohistochemical panel. METHODS: Forty-six adenomas were assessed by morphology and ß-catenin, serum amyloid A, and glutamine synthetase immunostains. RESULTS: Morphologic examination produced a morphologic working diagnosis of inflammatory adenoma in 25 (54%) of 46 cases, ß-catenin-activated adenoma in three (7%) of 46 cases, and 18 (39%) of 46 cases of other adenomas. After immunohistochemical staining, the morphologic diagnosis was confirmed in 15 (33%) of 46 and changed in 20 (43%) of 46, for a final distribution of 16 (35%) of 46 inflammatory adenomas, four (9%) of 46 ß-catenin-activated adenomas, seven (15%) of 46 ß-catenin-activated inflammatory adenomas, and 19 (41%) of 46 other adenomas. CONCLUSIONS: Inflammatory and ß-catenin-activated adenomas were readily identified by immunostaining patterns. These findings reinforce the necessity of immunohistochemistry in classifying adenomas, as assessing morphology alone often provided inaccurate subclassification. ß-Catenin-activated and inflammatory adenomas can be accurately diagnosed using only a limited panel of widely available immunostains.

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.

Hepatocellular adenoma classification: a comparative evaluation of immunohistochemistry and targeted mutational analysis.

BACKGROUND: Four subtypes of hepatocellular adenomas (HCA) are recognized: hepatocyte-nuclear-factor-1α mutated (H-HCA), ß-catenin-mutated type with upregulation of glutamine synthetase (b-HCA), inflammatory type (IHCA) with serum-amyloid-A overexpression, and unclassified type. Subtyping may be useful since b-HCA appear to have higher risk of malignant transformation. We sought to apply subtype analysis and assess histological atypia, correlating these with next-generation sequencing analysis. METHODS: Twenty-six HCA were stained with serum amyloid A (SAA), liver fatty acid-binding protein (LFABP), glutamine synthetase (GS), and ß-catenin IHC, followed by analysis with a targeted multiplex sequencing panel. RESULTS: By IHC, 4 HCA (15.4 %) were classified as b-HCA, 11 (42.3 %) as IHCA, 9 (34.6 %) as H-HCA, and two (7.7 %) unclassifiable. Eight HCA (30.8 %) showed atypia (3 b-HCA, 4 IHCA and 1 H-HCA). Targeted sequencing confirmed HNF1A mutations in all H-HCA, confirming reliability of LFABP IHC in identifying these lesions. CTNNB1 mutations were detected in 1 of 4 (25 %) of GS/ß-catenin-positive cases, suggesting that positive GS stain does not always correlate with CTNNB1 mutations. CONCLUSIONS: Immunohistochemistry does not consistently identify b-HCA. Mutational analysis improves the diagnostic accuracy of ß-catenin-mutated HCA and is an important tool to assess risk of malignancy in HCA.

[Hepatocellular adenoma - new classification and recommendations]. / Leveradenomer ­ ny klassifikation og anbefalinger

Hepatocellular adenoma (HCA) is a rare benign hepatocellular tumour developed in an otherwise healthy liver. The two main complications are bleeding from the HCA or malignant transformation to hepatocellular carcinoma (HCC). Risk factors for HCC include gender (men), size (> 8 cm) and subtype. Based on new molecular genetic analyses this review describes a new classification of adenomas using both genotype and phenotype. We want to provide an update on adenomas and give updated recommendations for diagnosis and treatment.

Pathological diagnosis of benign hepatocellular nodular lesions based on the new World Health Organization classification.

There are various types of benign hepatocellular nodular lesions, and their diagnostic criteria were formulated in detail. However, in 2010, the new World Health Organization (WHO) classification introduced immunohistochemical diagnostic criteria for hepatocellular adenoma (HCA) reflecting molecular pathological properties, and HCA was classified into 4 subtypes. These criteria were useful for its differential diagnosis from focal nodular hyperplasia (FNH). They were also useful for the diagnosis of HCA, its subtyping, and differentiation from FNH in Japan. However, the new WHO classification is based on principles that differ from those of conventional definitions of disease concepts and methods for the differential diagnosis. Therefore, it has caused disagreements in the diagnosis in some cases. Based on this background, we present a new perspective on the diagnosis of benign hepatocellular nodular lesions.

Hepatocellular adenomas in a large community population, 2000 to 2010: reclassification per current World Health Organization classification and results of long-term follow-up.

The data used for the World Health Organization classification of hepatocellular adenoma (HCA) is largely based on cases from tertiary level centers in Europe. This study examines the distribution of HCA subtypes in a large community population and determines the impact of immunohistochemistry (IHC) on reclassification, diagnosis, and management. All cases diagnosed as HCA in a large community hospital network from 2000 to 2010 were reviewed. The following immunohistochemical stains were evaluated in cases where paraffin-embedded tissue was available (n = 35): ß-catenin, glutamine synthetase, serum amyloid A, C-reactive protein, liver fatty acid binding protein. Twenty-eight of 35 cases were confirmed to be HCA, 5 cases were reclassified as well-differentiated hepatocellular carcinoma, and 2 cases were reclassified as focal nodular hyperplasia. The HCA cases were further subclassified into hepatocyte nuclear factor 1α inactivated (29%), inflammatory (32%), inflammatory with ß-catenin activation (3%), noninflammatory ß-catenin activated (0%), and unclassified (36%). Long-term follow-up was available on 33 of 35 cases, and there were no cases of recurrence or distant metastasis. IHC can provide a definite HCA subtype in two-thirds of cases. HCA subtypes in this large community-based population differed from the prior large French studies, in that there were a greater proportion of unclassified adenomas and a virtual absence of ß-catenin-activated adenomas. It is likely that most ß-catenin-activated hepatocellular tumors show morphologic and reticulin staining abnormalities indicative of well-differentiated hepatocellular carcinoma. IHC for glutamine synthetase and serum amyloid A can identify cases with ß-catenin activation and aid in the distinction of inflammatory adenoma and focal nodular hyperplasia.

Retrospective study of hepatocellular adenomas based on the phenotypic classification system: A report from China.

A molecular and pathological classification system for hepatocellular adenomas (HCAs) was recently introduced in Europe, resulting in four major identified subgroups. Asian countries have a considerably lower incidence of HCA as well as a different etiology. We aimed to characterize HCAs in a Chinese population based on this new classification system. A series of 30 patients with HCA were analyzed based on the phenotypic classification system using immunohistochemical analysis. Investigated antigens included liver-fatty acid binding protein (L-FABP), glutamine synthetase (GS), ß-catenin, serum amyloid A (SAA), and C-reactive protein (CRP). Of the 30 cases (20 female) included in this study, only one had a history of oral contraceptive use. We identified 9 (30%) hepatocyte nuclear factor (HNF)-1α-inactivated HCAs, 3 (10%) ß-catenin-activated HCAs, 11 (36.7%) inflammatory HCAs, and 7 (23.3%) unclassified HCAs. In the inflammatory HCA group, 2 cases demonstrated concurrent ß-catenin-activation. Homogeneous steatosis (6/9) and microadenomas (2/9) were more frequently observed in HNF1α-inactivated HCAs. A body mass index (BMI) of greater than 25 (5/11), alcohol use (4/11), and steatosis in background liver (3/11) were more frequent in inflammatory HCAs. ß-catenin-activated HCAs were larger than those of other subgroups. Despite obvious differences in etiology and gender proportion compared with Western countries, the clinical and pathological characteristics of HCA subgroups in China are similar to those in Europe. The phenotypic classification system could be reliably applied to Chinese patients as a meaningful tool for HCA management.

Benign hepatocellular nodules: what have we learned using the patho-molecular classification.

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are benign hepatocellular tumors that develop most frequently in females and in non-cirrhotic livers. HCA are prone to bleed and to transform into hepatocellular carcinoma (HCC). Four major subgroups of HCA have been thus far identified: HNF1α mutated HCA, inflammatory HCA (IHCA), ß-catenin mutated HCA (b-HCA and b-IHCA), based on mutations in specific oncogenes and tumor suppressors. B-HCA and b-IHCA are strongly associated with HCC transformation. Benign hepatocellular tumors can be classified using immunohistochemistry (LFABP, CRP, GS, b-catenin). Analysis of HCA phenotypes has led to the identification of patients at risk of HCC transformation and therefore improved the indications provided by invasive and non-invasive diagnostic techniques, such as biopsies and MRI. These recent advances have broadened the clinical scope of HCA in various conditions, such as their presence in males, in obese patients, in patients suffering from liver vascular disorders, genetic diseases. However, specific immunohistochemistry has shown limitations particularly for the identification of b-HCA, thereby, outlining the importance of molecular studies to improve the diagnosis/prognosis of HCA. If evaluation of prognosis and treatment has benefited from these advances, much more needs to be done to obtain guidelines for good clinical practice.

[Immunophenotypic classification of 3 cases of hepatocellular adenoma. Differential diagnosis with focal nodular hyperplasia]. / Clasificación inmunofenotípica de 3 casos de adenomas hepatocelulares. Diagnóstico diferencial con hiperplasia nodular focal.

Interest in adenomas has been renewed by the discovery of the molecular changes in these tumors. The latest World Health Organization publication on gastrointestinal tract tumors (2010) includes four types of hepatic adenomas, which are well characterized immunohistochemically, genotypically and phenotypically. In these tumors, medical history and morphological behavior play an important role in determining the risk of malignancy, mainly in adenomas with a b-catenin mutation. The presence of steatosis, inflammation, vascular changes linked to response to L-FABP, serum amyloid A, and glutamyl synthetase help to classify these tumors into four groups: hepatocellular adenomas with the HNF1A mutation (H-HCA), those with the b-catenin mutation (b-HCA), inflammatory HCA (IHCA), and HCA without markers. The absence of glypican 3 expression, HSP 70 and perivenular mapping of glutamyl synthetase helps to distinguish these tumors from well differentiated hepatocellular carcinoma. We describe the clinical, morphological and immunophenotypic features of three patients diagnosed with hepatic adenomas in a 2-year period.