Coexistence of inflammatory hepatocellular adenomas with HNF1α-inactivated adenomas: is there an association?

Unclassified hepatocellular adenoma expressing ASS1 associated with inflammatory hepatocellular adenomas

Three liver nodules were fortuitously discovered in a 30-year-old obese woman during a gynecological workup and resected. Two nodules (6 and 1.5 cm) with histological characteristics of inflammatory hepatocellular adenoma (HCA) were C reactive protein positive with normal expression of glutamine synthetase. The third 6 cm nodule had all the characteristics of an Unclassified HCA with an overexpression of Argininosuccinate Synthase 1 (ASS1) in the tumor compared to the non-tumoral liver. The non-tumoral liver was highly steatotic. Upon MRI review, two HCAs were identified as inflammatory HCAs based on specific criteria. The third HCA was different from the other two with the presence of peculiar intratumoral fluid cavities. This first report on the association between unclassified HCA expressing ASS1 and inflammatory HCA reinforces the concept that common factors are implicated in HCA subtypes genesis. ASS1 is an interesting immuno-marker to identify among unclassified HCA a subgroup with a high risk of bleeding. ASS1 overexpression decreases sharply the number of "true" unclassified HCA.

Unexpected discovery of small HNF1α-inactivated hepatocellular adenoma in pathological specimens from patients resected for liver tumours

BACKGROUND AND AIMS

It is rare but not uncommon to discover micro/small HNF1α-inactivated hepatocellular adenoma (H-HCA) outside the context of resected H-HCA. We aimed to review our cases of micro/small H-HCA discovered by chance on different kinds of liver resected specimens.

METHODS

We retrieved cases of micro/small H-HCA discovered by chance on resected specimens outside the context of H-HCA. All these nodules were liver fatty acid binding protein (LFABP)-negative contrasting with normal positivity in the surrounding non-tumoural liver, ruling out the possibility of focal steatosis or other subtypes of micro-HCAs.

RESULTS

We identified 19 micro/small H-HCA cases. In 16 cases they were discovered in patients who underwent surgery for benign nodules including one haemangioma, six focal nodular hyperplasia, seven inflammatory HCA (including one with b-catenin activation), one HCA, whose subtype could not be identified because of massive necrosis/hemorrhage, and one hepatocellular carcinoma. In two additional cases, patients followed up for a melanoma underwent liver surgery to remove micro nodules possibly related to a metastatic process. Finally in one case a micro nodule was seen and resected during a cholecystectomy.

CONCLUSION

Taken together, H-HCAs are more frequent than we initially supposed as micro and small HCAs cannot all be detected by routine ultrasound. Despite no information on the potential growth of these micro/small H-HCAs, there is no argument to stop oral contraceptives or to ask for a specific regular surveillance. The association of different subtypes of HCAs with focal nodular hyperplasia suggests they share or have common etiological factors.

A Limited Immunohistochemical Panel Can Subtype Hepatocellular Adenomas for Routine Practice

OBJECTIVES

β-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 β-catenin-activated and inflammatory adenomas could be identified using a limited immunohistochemical panel.

METHODS

Forty-six adenomas were assessed by morphology and β-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, β-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 β-catenin-activated adenomas, seven (15%) of 46 β-catenin-activated inflammatory adenomas, and 19 (41%) of 46 other adenomas.

CONCLUSIONS

Inflammatory and β-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. β-Catenin-activated and inflammatory adenomas can be accurately diagnosed using only a limited panel of widely available immunostains.

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.

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.

Liver transplantation for adenomatosis: European experience

The aim of this study was to collect data from patients who underwent liver transplantation (LT) for adenomatosis; to analyze the symptoms, the characteristics of the disease, and the recipient outcomes; and to better define the role of LT in this rare indication. This retrospective multicenter study, based on data from the European Liver Transplant Registry, encompassed patients who underwent LT for adenomatosis between January 1, 1986, and July 15, 2013, in Europe. Patients with glycogen storage disease (GSD) type IA were not excluded. This study included 49 patients. Sixteen patients had GSD, and 7 had liver vascular abnormalities. The main indications for transplantation were either a suspicion of hepatocellular carcinoma (HCC; 15 patients) or a histologically proven HCC (16 patients), but only 17 had actual malignant transformation (MT) of adenomas. GSD status was similar for the 2 groups, except for age and the presence of HCC on explants (P = 0.030). Three patients with HCC on explant developed recurrence after transplantation. We obtained and studied the pathomolecular characteristics for 23 patients. In conclusion, LT should remain an extremely rare treatment for adenomatosis. Indications for transplantation primarily concern the MT of adenomas. The decision should rely on morphological data and histological evidence of MT. Additional indications should be discussed on a case-by-case basis. In this report, we propose a simplified approach to this decision-making process.

Hepatocellular nodules expressing markers of hepatocellular adenomas in Budd-Chiari syndrome and other rare hepatic vascular disorders

BACKGROUND & AIMS

A broad range of hepatocellular nodules has been reported in hepatic vascular disorders. It is not clear whether hepatocellular adenoma (HCA) in this context share the same characteristics as conventional HCA. The aim of this study was to carry out a retrospective multicenter survey of hepatocellular nodules associated with hepatic vascular disorders.

METHODS

Forty-five cases were reviewed, including 32 Budd-Chiari syndrome (BCS). Benign nodules were subtyped using the HCA immunohistochemical panel.

RESULTS

Nodules with a HCA morphology were observed in 11 cases. Six originated in BCS: two were liver fatty acid binding protein (LFABP) negative (one with malignant transformation); two expressed glutamine synthetase (GS) and nuclear b-catenin, two expressed C reactive protein (CRP). Among three cases with portal vein agenesis, one nodule was LFABP negative, two expressed GS and nuclear b-catenin, both with malignant transformation. In a Fallot tetralogy case, there were multiple LFABP negative nodules with borderline features and in a hepatoportal sclerosis case, the nodule looked like an inflammatory HCA. Two additional cases had nodules expressing CRP, without typical characteristics of inflammatory HCA.

CONCLUSION

HCA of different immunohistochemical phenotype can develop in hepatic vascular disorders; they may have a different behavior compared to conventional HCA and be more at risk of malignant transformation.

Current Proceedings in the Molecular Dissection of Hepatocellular Adenomas: Review and Hands-on Guide for Diagnosis

Molecular dissection of hepatocellular adenomas has brought forward a diversity of well-defined entities. Their distinction is important for routine practice, since prognosis is tightly related to the individual subgroup. Very recent activity has generated new details on the molecular background of hepatocellular adenoma, which this article aims to integrate into the current concepts of taxonomy.

Steatotic hepatocellular adenomas with different phenotypic subtypes: a case report

Hepatocellular adenomas (HCAs) are heterogeneous group of benign tumors; three pathomolecular subtypes have been identified so far: hepatocyte nuclear factor 1 α-inactivated HCA (H-HCA) (35-40%), inflammatory HCA (I-HCA) (>50%), β-catenin activated HCA (10%). Ten percent of I-HCA are also β-catenin activated. We report a rare case of three histologically confirmed steatotic HCAs of three different phenotypes: I-HCA, β-catenin activated I-HCA, and H-HCA in a 36-year-old woman. This observation outlines that in the same patient, HCA may be of different subtypes. The predisposition to develop different HCA hypothetically caused by a "benign tumorigenic field effect" may result, even rarely, in different genotypes/phenotypes such as H-HCA and I-HCA. Moreover, we illustrate the very high specificity of MR for subtyping HCA.