Complementary roles of β-catenin and glutamine synthetase immunostaining in diagnosis of chemotherapy-treated and untreated hepatoblastoma

Background/Purpose This study aimed to evaluate the expression of β-catenin and its downstream target glutamine synthetase (GS) in hepatoblastoma (HB), and to evaluate the use of these two markers for diagnosing HB. Methods Eighteen untreated HBs and 22 HBs resected after neoadjuvant chemotherapy were analyzed using β-catenin and GS immunostaining. Results We detected nuclear β-catenin immunostaining in nearly all untreated HBs, including in fetal and embryonal epithelial components and in mesenchymal elements. We also observed diffuse GS expression in the epithelial component; however, it was frequently absent in embryonal and mesenchymal areas. In HBs resected after neoadjuvant chemotherapy, we recognized four histological patterns: fetal, hepatocellular-carcinoma-like, clear-cell, and normal-liver-like. All these patterns displayed diffuse GS expression. Fetal pattern showed diffuse nuclear β-catenin immunostaining. Nuclear β-catenin immunostaining was weak in the hepatocellular-carcinoma-like and clear-cell patterns. In normal-liver-like area, β-catenin expression was only located in the cell membrane. Conclusion The results suggest that nuclear β-catenin expression and diffuse GS immunostaining are the hallmarks of HB. Although epithelial and mesenchymal components of HB display nuclear β-catenin staining, this expression is attenuated following chemotherapy-induced cell maturation. GS immunostaining is especially useful for the assessment of section margins after neoadjuvant chemotherapy. ? 2016