Lesson Of The Month A Difficult Case Of Beta-Catenin-Mutated Hepatocellular Adenoma: A Lesson For Diagnosis

Hepatocellular adenoma with mutations in CTNNB1 gene coding for β-catenin (b-HCA) are subdivided into several groups based on different mutations/deletions in exon 3 (non-S45, and S45) and exon 7 or 8, leading to different levels of β-catenin pathway activation (1). The distinction is clinically relevant because mutation in exon 3 (including S45) is associated with a risk of malignant transformation (2); this risk is absent or very low for mutations in exon 7/8 (1). The glutamine synthetase (GS), a key immunohistochemical marker for the identification of mutations in CTNNB1 gene, presents different staining/pattern depending the mutations. Indeed, in exon 3 non-S45 mutations, GS staining is diffuse and strong, usually homogeneous. This article is protected by copyright. All rights reserved.