Hepatocellular Neoplasms with Loss of Liver Fatty Acid Binding Protein: Clinicopathologic Features and Molecular Profiling

Role of genomic analysis in the classification of well differentiated hepatocellular lesions

BACKGROUND

The distinction of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) from well-differentiated hepatocellular carcinoma (WD-HCC) in noncirrhotic liver can be challenging. High-grade dysplastic nodule (HGDN) in cirrhosis can have overlapping features with WD-HCC. In some cases, HCA diagnosis is evident but glutamine synthetase (GS) staining is indeterminate for β-catenin activation, which does not allow reliable risk assessment. This study examines the role of genomic analysis in better categorization of WD hepatocellular lesions (WDHL).

DESIGN

Genomic analysis using capture-based NGS assay was done in 23 WDHLs that could not be definitely classified based on morphology, reticulin stain and IHC, and were designated as 'atypical hepatocellular neoplasms' (AHNs). GS staining was classified as diffuse homogeneous (moderate to strong staining in >90% of tumor cells), diffuse heterogeneous (50-90%), not diffuse (<50%) and borderline (not clear if more or less than 50%).

RESULTS

The genomic profile provided additional information for the diagnosis and/or risk assessment enabling a benign diagnosis in 15/23 cases (66%) and HCC in 4/23 cases (17%), while the diagnosis remained as atypical in the remaining 4 cases. Of the 4 cases with final HCC diagnosis, findings were suspicious but not diagnostic based on morphology/IHC; additional changes like TERT promoter mutation (n=2), AXIN mutation (n=1), CDKN2A loss (n=2) and copy number alterations (n=3) helped to support HCC. Of the 15 cases with a final benign diagnosis, the status of β-catenin activation was unclear based on GS stain in 8 cases, 2 of which showed CTNNB1 exon 7 mutation, 1 showed CTNNB1 exon 8 mutation, while genomic changes in 5 cases did not show any evidence of Wnt activation. FNH-like features were seen in 2 cases, but the genomic changes excluded FNH (CTNNB1 and ARID1A mutation). The final diagnosis was unchanged from the initial diagnosis of AHN in 4/23 cases (17%) as the molecular findings did not favor HCC.

CONCLUSION

Genomic changes were helpful in characterization of WDHLs, supporting HCC in 17% of cases and clarifying β-catenin activation status in all 7 cases with borderline GS staining. Genomic changes are not specific but can provide diagnostic clues in selected challenging cases that cannot be classified on morphology and IHC. Given the significant treatment implications of distinguishing between HCC and benign/premalignant entities, routine use of genomic analysis in diagnostically challenging settings should be considered.

Clinicopathologic features and prognosis of steatohepatitic hepatocellular carcinoma based on varying cutoffs of tumoral steatohepatitic changes

OBJECTIVES

Steatohepatitic hepatocellular carcinoma (SH-HCC) is currently recognized as a distinct histologic subtype of HCC. The prognosis and specific criteria for determining the amount of steatohepatitis required to define SH-HCC are still unclear.

METHODS

After excluding all recognized HCC subtypes from 505 HCC cases (2010-2019), the remaining cases were categorized as conventional HCC (CV-HCC) (n = 223). The cases classified as SH-HCC (n = 171) were further divided into groups based on the percentage of steatohepatitis: 5% or more, 30% or more, and 50% or more.

RESULTS

Hepatitis C virus infection was the predominant underlying liver disease in both the CV-HCC and SH-HCC groups. Metabolic dysfunction-associated steatotic liver disease (formerly nonalcoholic fatty liver disease) was more prevalent in all cases of SH-HCC with different steatohepatitic cutoffs than in cases of CV-HCC. There were no differences in the stage of fibrosis of the background liver between the CV-HCC and SH-HCC groups. SH-HCC with different cutoffs exhibited a notable increase in the presence of glycogenated nuclei, Mallory-Denk bodies, and hyaline globules in tumor cells. Survival analysis did not reveal substantial differences in overall survival between the CV-HCC and SH-HCC groups and among patients with SH-HCC with different steatohepatitis cutoffs.

CONCLUSIONS

The degree of intratumoral steatohepatitis in patients with SH-HCC does not appear to be a notable prognostic factor. The presence of steatohepatitis in the tumor is better recognized as 1 of the histopathologic patterns of HCC.

Hepatic Precancerous Lesions and Early Hepatocellular Carcinoma

This review discusses the diagnostic challenges of diagnosing and treating precursor lesions of hepatocellular carcinoma (HCC) in both cirrhotic and non-cirrhotic livers. The distinction of high-grade dysplastic nodule (the primary precursor lesion in cirrhotic liver) from early HCC is emphasized based on morphologic, immunohistochemical, and genomic features. The risk factors associated with HCC in hepatocellular adenomas (precursor lesion in non-cirrhotic liver) are delineated, and the risk in different subtypes is discussed with emphasis on terminology, diagnosis, and genomic features.

Evaluating Liver Biopsies with Well-Differentiated Hepatocellular Lesions

Needle core biopsies of liver lesions can be challenging, particularly in cases with limited material. The differential diagnosis for well-differentiated hepatocellular lesions includes focal nodular hyperplasia, hepatocellular adenoma, and well-differentiated hepatocellular carcinoma (HCC) in noncirrhotic liver, while dysplastic nodules and well-differentiated HCC are the primary considerations in cirrhotic liver. The first part of this review focuses on histochemical and immunohistochemical stains as well as molecular assays that are useful in the differential diagnosis. The second portion describes the features of hepatocellular adenoma subtypes and focuses on the differential diagnoses in commonly encountered clinicopathologic scenarios.

Etiology, Pathogenesis, Diagnosis, and Practical Implications of Hepatocellular Neoplasms

Hepatocellular carcinoma (HCC), a major global contributor of cancer death, usually arises in a background of chronic liver disease, as a result of molecular changes that deregulate important signal transduction pathways. Recent studies have shown that certain molecular changes of hepatocarcinogenesis are associated with clinicopathologic features and prognosis, suggesting that subclassification of HCC is practically useful. On the other hand, subclassification of hepatocellular adenomas (HCAs), a heterogenous group of neoplasms, has been well established on the basis of genotype–phenotype correlations. Histologic examination, aided by immunohistochemistry, is the gold standard for the diagnosis and subclassification of HCA and HCC, while clinicopathologic correlation is essential for best patient management. Advances in clinico-radio-pathologic correlation have introduced a new approach for the diagnostic assessment of lesions arising in advanced chronic liver disease by imaging (LI-RADS). The rapid expansion of knowledge concerning the molecular pathogenesis of HCC is now starting to produce new therapeutic approaches through precision oncology. This review summarizes the etiology and pathogenesis of HCA and HCC, provides practical information for their histologic diagnosis (including an algorithmic approach), and addresses a variety of frequently asked questions regarding the diagnosis and practical implications of these neoplasms.

Hepatic Adenomas in Patients 60 and Older Are Enriched for HNF1A Inactivation and Malignant Transformation

Hepatic adenomas occur most commonly in women between the ages of 20 and 40 years, but rarely they occur in older aged persons, including those 60 years of age or older. This group of adenomas, however, has not been systemically examined. Twenty-six hepatic adenomas in persons 60 years of age or older were studied, along with a control group of 50 hepatic adenomas in persons aged 30 to 39. Hepatic adenomas in persons 60 or more years of age were found in 21 women and 5 men, while the control group had 44 women and 6 men. Subtyping the adenomas in persons 60 years or older showed the following results: 18 HNF1A-inactivated adenomas (69%), 4 inflammatory adenomas (15%), and 4 unclassified adenomas (15%). In contrast, the control group showed a significantly different pattern (P=0.003), with a greater percentage of inflammatory adenomas (28, 56%), fewer HNF1A-inactivated adenomas (8, 16%), and more unclassified adenomas (14, 28%). Atypia and malignant transformation within the hepatic adenomas was studied next. Of the hepatic adenomas in persons age 60 or greater, 3 (12%) showed atypical histologic features, and 6 (23%) had a malignant transformation. In contrast, for hepatic adenomas in the control group, only 4 (8%) adenomas showed atypical histologic features, and 3 (6%) had undergone malignant transformation. In addition, the hepatic adenomas that were atypical or showed early malignant transformation were less likely to have beta-catenin activation in patients over 60 (2/9 cases) compared with those between 30 and 39 years (5/7 cases). Myxoid change and heavy lipofuscin deposition were also more common in adenomas in older aged persons. In conclusion, hepatic adenomas in persons 60 years of age or older are enriched for HNF1A-inactivated adenomas and have a higher frequency of malignant transformation. Malignant transformation, however, is less likely to develop through activation of the beta-catenin pathway.