Fibrolamellar HCC possess distinctive immunophenotypic characteristics featuring uniform CK7 and epithelial membrane antigen (EMA) positivity (100% vs. <33% in conventional HCC), while maintaining expression of hepatocellular markers including HepPar1 (sensitivity of 78% vs. 85%, compared to conventional HCC) and variable GPC3 expression (59% vs. 39% in conventional HCC) [96]. The gene discussed is GPC3; the disease is hepatocellular carcinoma.