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

Hepatocellular Adenomas: Molecular Basis and Multimodality Imaging Update

Hepatocellular adenomas (HCAs) are a family of liver tumors that are associated with variable prognoses. Since the initial description of these tumors, the classification of HCAs has expanded and now includes eight distinct genotypic subtypes based on molecular analysis findings. These genotypic subtypes have unique derangements in their cellular biologic makeup that determine their clinical course and may allow noninvasive identification of certain subtypes. Multiphasic MRI performed with hepatobiliary contrast agents remains the best method to noninvasively detect, characterize, and monitor HCAs. HCAs are generally hypointense during the hepatobiliary phase; the β-catenin-mutated exon 3 subtype and up to a third of inflammatory HCAs are the exception to this characterization. It is important to understand the appearances of HCAs beyond their depictions at MRI, as these tumors are typically identified with other imaging modalities first. The two most feared related complications are bleeding and malignant transformation to hepatocellular carcinoma, although the risk of these complications depends on tumor size, subtype, and clinical factors. Elective surgical resection is recommended for HCAs that are persistently larger than 5 cm, adenomas of any size in men, and all β-catenin-mutated exon 3 HCAs. Thermal ablation and transarterial embolization are potential alternatives to surgical resection. In the acute setting of a ruptured HCA, patients typically undergo transarterial embolization with or without delayed surgical resection. This update on HCAs includes a review of radiologic-pathologic correlations by subtype and imaging modality, related complications, and management recommendations. ^© RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Body weight changes and duration of estrogen exposure modulate the evolution of hepatocellular adenomas after contraception discontinuation

BACKGROUND AND AIMS

The natural history of hepatocellular adenomas (HCAs) remains to be better described, especially in nonresected patients. We aim to identify the predictive factors of HCA evolution after estrogen-based contraception discontinuation.

APPROACH AND RESULTS

We retrospectively included patients with a histological diagnosis of HCA from three centers. Clinical, radiological, and pathological data were collected to identify predictive factors of radiological evolution per Response Evaluation Criteria in Solid Tumors, version 1.1, and occurrence of complications (bleeding, malignant transformation). We built a score using variables that modulate estrogen levels: body mass index and duration of estrogen-based contraception. An external cohort was used to validate this score. 183 patients were included in the cohort, including 161 women (89%) using estrogen-based contraception for a median of 12 years. Thirty percent of patients had at least one HNF1A -inactivated HCA, 45.5% at least one inflammatory HCA, and 11% at least one HCA with activation of β-catenin (bHCA). Twenty-one symptomatic bleedings (11%) and eleven malignant transformations (6%) occurred. Ages < 37 years old ( p = 0.004) and HCA > 5 cm at imaging were independently associated with symptomatic bleeding ( p = 0.003), whereas a bHCA was associated with malignant transformation ( p < 0.001). After a median follow-up of 5 years, radiological regression was observed in 31%, stabilization in 47%, and progression in 22% of patients. Weight loss was associated with regression ( p < 0.0001) and weight gain with progression ( p = 0.02). The estrogen exposure score predicted radiological regression (odds ratio, 2.33; confidence interval 95%, 1.29-4.19; p = 0.005) with a linear relationship between the rate of estrogen exposure and the probability of regression. This result was confirmed in an external cohort of 72 female patients ( p = 0.003).

CONCLUSION

Weight variation is strongly associated with radiological evolution after oral contraception discontinuation. A score of estrogen exposure, easily assessable in clinical practice at diagnosis, predicts regression of HCA.

Benign liver tumours: understanding molecular physiology to adapt clinical management

Improvements in understanding the pathophysiology of the different benign liver nodules have refined their nosological classification. New criteria have been identified using imaging, histology and molecular analyses for a precise diagnosis of these tumours. Improvement in the classification of liver tumours provides a more accurate prediction of disease progression and has modified patient management. Haemangioma and focal nodular hyperplasia, the most common benign liver tumours that develop in the absence of chronic liver disease, are usually easy to diagnose on imaging and do not require specific treatment. However, hepatocellular adenomas and cirrhotic macronodules can be difficult to discriminate from hepatocellular carcinoma. The molecular subtyping of hepatocellular adenomas in five major subgroups defined by HNF1A inactivation, β-catenin mutation in exon 3 or exon 7/8, and activation of inflammatory or Hedgehog pathways helps to identify the tumours at risk of malignant transformation or bleeding. New clinical, biological and molecular tools have gradually been included in diagnostic and treatment algorithms to classify benign liver tumours and improve patient management. This Review aims to explain the main pathogenic mechanisms of benign liver tumours and how this knowledge could influence clinical practice.

Hepatocellular Adenoma: What We Know, What We Do Not Know, and Why It Matters

In the last 2 decades there has been significant progress in research and diagnosis of hepatocellular adenoma (HCA), resulting in the establishment of a molecular and immunohistological HCA classification. This review aims to fine-tune the current expertise in order to enhance the histopathological diagnostic possibilities, by refining issues that are already known, addressing diagnostic difficulties and identifying still unknown aspects of HCA. We will discuss novel methods to identify HCA subtypes, in particular the sonic hedgehog HCAs and the interpretation of glutamine synthetase patterns for the recognition of beta-catenin mutated HCAs. The major complications of HCAs, bleeding and malignant transformation, will be considered, including the dilemmas of atypical and borderline lesions. Paragraphs on HCAs in different clinical and geographical settings, e.g. pregnancy, cirrhosis and non-western countries are included. The natural history of the different HCA subtypes in relation with age, sex and risk factors is a feature still insufficiently investigated. This is also true for the risks of clinical bleeding and malignant transformation in association with HCA subtypes. As HCA is a relatively rare tumor, a multicenter and multidisciplinary approach across geographical boundaries will be the appropriate method to establish prospective programs to identify, classify and manage HCAs, focusing on several aspects, e.g. etiology, underlying liver disease, complications, regression and growth. Updating what we know, identifying and addressing features that we do not know matters to warrant optimal patient management.

Predictive Patterns of Glutamine Synthetase Immunohistochemical Staining in CTNNB1-mutated Hepatocellular Adenomas

Some hepatocellular adenoma (HCA) subtypes are characterized by different CTNNB1 mutations, leading to different beta-catenin activation levels, hence variable immunostaining patterns of glutamine synthetase (GS) expression, and different risks of malignant transformation. In a retrospective multicentric study of 63 resected inflammatory (n=33) and noninflammatory (n=30) molecularly confirmed CTNNB1-mutated b-(I)HCA, we investigated the predictive potential of 3 known GS patterns as markers for CTNNB1 exon 3, 7/8 mutations. Pattern 1 (diffuse homogenous) allowed recognition of 17/21 exon 3 non-S45 mutated b-(I)HCA. Pattern 2 (diffuse heterogenous) identified all b-(I)HCA harboring exon 3 S45 mutation (20/20). Pattern 3 (focal patchy) distinguished 12/22 b-(I)HCA with exon 7/8 mutations. In exon 3 S45 and 7/8 mutations, both b-HCA and b-IHCA showed a GS+/CD34- rim with diffuse CD34 positivity in the center of the lesion. Interobserver reproducibility was excellent for exon 3 mutations. Comparative analysis of GS patterns with molecular data showed 83% and 80% sensitivity (b-HCA/b-IHCA) and 100% specificity for exon 3 non-S45. For exon 3 S45, sensitivity was 100% for b-(I)HCA, and specificity 93% and 92% (b-HCA/b-IHCA). For exon 7/8, sensitivity was 55% for both subtypes and specificity 100% and 96% (b-HCA/b-IHCA). Preliminary data from 16 preoperative needle biopsies from the same patients suggest that this panel may also be applicable to small samples. In surgically resected HCA, 2 distinct GS patterns can reliably predict CTNNB1 exon 3 mutations, which are relevant because of the higher risk for malignant transformation. The third pattern, although specific, was less sensitive for the identification of exon 7/8 mutation, but the GS+/CD34- rim is a valuable aid to indicate either an exon 3 S45 or exon 7/8 mutation.

Malignant transformation of liver fatty acid binding protein-deficient hepatocellular adenomas: histopathologic spectrum of a rare phenomenon

The molecular classification of hepatocellular adenomas highlights a distinctive genotype-phenotype correlation. Malignant transformation is an exceptionally rare complication of hepatocyte nuclear factor 1α (HNF1A)-inactivated hepatocellular adenomas. This subtype is characterized by loss of liver fatty acid binding protein immunoexpression. In this study, we characterized the histopathologic spectrum of 13 liver fatty acid binding protein-deficient hepatocellular adenoma cases showing malignant transformation from multiple centers. Clinicopathologic characteristics of these patients were evaluated. Stains for reticulin, liver fatty acid binding protein, beta-catenin and glutamine synthetase were applied to these lesions. Moreover, the findings were compared to patients with β-catenin mutated hepatocellular adenoma. Liver fatty acid binding protein-deficient hepatocellular adenomas with borderline features/carcinoma were seen predominantly in females (77%) with an average age of 46 ± 18 years and multiple lesions (77%; five patients with adenomatosis). Meanwhile, β-catenin mutated hepatocellular adenoma patients with malignant transformation were predominantly male (67%, p = 0.018) with single lesion (86%, p = 0.0009). The largest liver fatty acid binding protein-deficient hepatocellular adenoma nodule in each patient ranged from 4 to 15.5 cm. Loss of liver fatty acid binding protein by immunohistochemistry was noted in all adenoma and borderline/carcinoma components. Features of malignant transformation were pseudoglandular architecture (85%), cytologic atypia (85%), architectural atypia (100%) and lack of steatosis (100%). Other findings included myxoid change (39%), peliosis (46%) and sinusoidal dilatation (46%). Molecular studies confirmed somatic inactivation of HNF1A in 3 cases and absence of TERT promotor and exon 3 CTNNB1 mutations in five cases. To summarize, liver fatty acid binding protein-deficient hepatocellular adenoma with malignant transformation is most frequently seen in female patients with multiple lesions. Most of these lesions demonstrate pseudoglandular architecture, cytologic and architectural atypia, with lack of steatosis. The natural history of these lesions is relatively benign with the exception of disease recurrence in 1 patient.

Repeat surgery in HNF1alpha-inactivated adenomatosis

BACKGROUND AND AIMS

Stopping oral contraceptives following nodule detection usually prevents further hepatocellular growth (HCA); rare cases of growth have been reported after surgery. The aim of the study was to review our resected HCA cases and their outcomes and more specifically, growth.

METHODS

We retrieved all HCA cases that required a second intervention and HCA growth cases of none resected HCA after resection of one or several HCAs.

RESULTS

Out of the 210 resected classified HCA cases, a second resection was performed in 5 cases, 4 of which were in women with HNF1alpha-inactivated adenomatosis (H-adenomatosis) and had a favorable outcome. The fifth case was the occurrence of an inflammatory HCA, 3 years after resection of a previous one. Of the 65 resected HNF1-inactivated HCAs (H-HCAs), the nodules that remained continued to increase very slowly in 3 adenomatosis cases. After surgery, the liver became dysmorphic years later in one case, and the nodules grew but not significantly in another case. After the diagnosis of adenomatosis, progressive growth leads to surgery 12 years later in the last case.

CONCLUSION

These results confirm that, in rare H-adenomatosis, size of nodules may increase very slowly, probably in part through coalescence of micro H-HCAs and leading occasionally to a second resection.

Current Approaches in the Management of Hepatic Adenomas

INTRODUCTION

Hepatic adenomas (HAs) are a benign and relatively rare type of liver neoplasms. We review the diagnosis, evaluation, and potential therapeutic management options for patients with HA.

METHODS

A comprehensive review of the English literature was performed utilizing MEDLINE/PubMed and Web of Science databases with end of search date the 30th April of 2018. In PubMed, the terms "hepatocellular," "hepatic," "liver," and "adenoma," "adenomatosis" were searched in the title and/or abstract.

RESULTS

Recent advances in molecular classification of HA have determined distinct subtypes with specific clinical, pathological, and imaging characteristics. In general, cessation of exogenous hormonal administration or weight loss may lead to HA regression. Surgical resection, either open or laparoscopic, should be considered in patients with symptoms and risk factors for hemorrhage or malignant transformation. These risk factors include tumor diameter greater than 5 cm, β-catenin activated subtype, and/or male gender. The management of acute hemorrhage should primarily aim at achieving hemodynamic stability via angioembolization followed by elective resection, whereas malignant transformation is treated according to oncologic resection principles. Although pregnancy is one of the known risk factors for tumor growth and associated complications, the presence of an HA per se should not be considered a contradiction to pregnancy.

CONCLUSION

Future genomic-based multicenter studies are required to provide a strong basis for formulating an evidence-based risk-adapted model that guides individualized management strategies for patients with HA.

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 β-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.

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.