RGD Reference Report - Hepatic angiomyolipoma: mutation analysis and immunohistochemical pitfalls in diagnosis. - Rat Genome Database

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Hepatic angiomyolipoma: mutation analysis and immunohistochemical pitfalls in diagnosis.

Authors: Yan, Zhen  Grenert, James P  Joseph, Nancy M  Ren, Chuanli  Chen, Xin  Shafizadeh, Nafis  Kakar, Sanjay 
Citation: Yan Z, etal., Histopathology. 2018 Jul;73(1):101-108. doi: 10.1111/his.13509. Epub 2018 Apr 19.
RGD ID: 21079730
Pubmed: (View Article at PubMed) PMID:29512829
DOI: Full-text: DOI:10.1111/his.13509

AIMS: Hepatic angiomyolipoma (AML) often shows epithelioid morphology with inconspicuous fat. Epithelioid component can mimic hepatocellular adenoma (HCA) or carcinoma (HCC). The aims of this study were to examine the expression of commonly used markers for HCA or HCC in hepatic AML and highlight pitfalls in diagnosis.
METHODS AND RESULTS: Resected hepatic AMLs (n = 16) were reviewed; reticulin stain, immunohistochemistry for glutamine synthetase (GS), β-catenin and liver fatty acid binding protein (LFABP) were performed along with Sanger sequencing of exon 3 of CTNNB1 and next-generation sequencing (NGS). Predominant epithelioid component (>=50%) was seen in 80% of cases. Foamy macrophage was present in 33% of cases. High-risk histological features were often present in tumours with benign outcome: marked atypia (19%), mitoses (20%) and necrosis (33%). GS staining (>=10% of tumour) was seen in epithelioid components in 13 (87%) cases, and was diffuse (>50% of tumour) in six (40%) cases. LFABP staining or nuclear β-catenin staining was not seen in any case. Sanger sequencing and NGS did not reveal CTNNB1 mutation in any tested case. NGS demonstrated TSC2 mutations in all five cases tested.
CONCLUSIONS: The predominance of epithelioid component resembling HCA or HCC is common in hepatic AML. Absence of LFABP and presence of fat can be mistaken for HNF1α-inactivated HCA. Diffuse GS staining can be mistaken for β-catenin-activated HCA or HCC. Diffuse GS expression is not related to CTNNB1 mutation. All tested cases showed TSC2 mutation, supporting this as the driving genetic event for hepatic AML.


Disease Annotations    

Objects Annotated

Genes (Rattus norvegicus)
Tsc2  (TSC complex subunit 2)

Genes (Mus musculus)
Tsc2  (TSC complex subunit 2)

Genes (Homo sapiens)
TSC2  (TSC complex subunit 2)

Additional Information