Hepatocellular Carcinoma with β-Catenin Mutation: Imaging and Pathologic Characteristics

Purpose To identify the imaging features of hepatocellular carcinoma (HCC) associated with β-catenin mutation and their relationship to pathologic findings. Materials and Methods Institutional ethics committee approval and informed consent were obtained. One hundred thirty-eight surgically resected HCCs were analyzed in this study. Immunohistochemical expression of β-catenin and its transcriptional product, glutamine synthetase (GS), were graded and classified into three groups: the β-catenin positive and GS positive group (HCC with β-catenin mutation), the β-catenin negative and GS positive group (intermediate HCC), and the β-catenin negative and GS negative group (HCC without β-catenin mutation). Clinical, pathologic, and imaging findings from dynamic computed tomography (CT) and gadoxetic acid–enhanced magnetic resonance (MR) imaging (T1-weighted, T2-weighted, diffusion-weighted, and hepatobiliary phase imaging) were evaluated. Correlations among immunohistochemical expression of β-catenin, GS, and organic anion transporting polypeptide 1B3 (uptake transporter of gadoxetic acid) were evaluated. The χ2, Kruskal-Wallis, and Spearman correlation tests were used. Results HCCs with β-catenin mutation (n = 27) showed a lower median contrast-to-noise ratio at diffusion-weighted imaging than did intermediate HCCs (n = 23) and HCCs without β-catenin mutation (n = 84) (13.2, 24.4, and 27.0, respectively; P = .02), higher apparent diffusion coefficient (1.33, 1.13, and 1.12, respectively; P < .0001), higher contrast-to-noise ratio (0.58, −28.7, and −45.0, respectively; P < .0001) and higher enhancement ratio during the hepatobiliary phase (0.90, 0.50, and 0.42, respectively; P < .0001). At pathologic examination, HCCs with β-catenin mutation showed pseudoglandular proliferation and bile production with a higher grade of differentiation (P = .04, .001, and .005, respectively). There were significant positive correlations among expression of β-catenin, GS, and organic anion transporting polypeptide 1B3 (P < .0001). Conclusion HCCs with β-catenin mutation showed a higher grade of differentiation with frequent pseudoglandular patterns and bile production, and characteristic imaging findings included a high enhancement ratio at gadoxetic acid–enhanced MR imaging and a high apparent diffusion coefficient at diffusion-weighted imaging. © RSNA, 2015 Online supplemental material is available for this article.