Figure 6.

Immunohistochemical evaluation of β-catenin membranous expression. (a) Area of a LUAC showing strong complete β-catenin membranous staining in 95% of the tumor cells, scored as 3: “high”. (b) Area of an LSCC showing heterogeneous β-catenin membranous expression. There is coexistence of areas of tumor cells that exhibit strong and complete membranous staining (peripheric zones) and areas with tumor cells showing moderate–weak β-catenin membranous expression (centrally). The latter is observed in 60% of the tumor cells, and therefore is scored as 2: “moderate”. Distinct, patchy foci of single cells and small groups of cells with vanishing or lost membranous expression are also present. (c) Area of a LUAC with complete membranous staining preservation of moderate–strong intensity in >70% of cells, scored as 3: “high”. (d) An area of a LUAC showing vanishing β-catenin membranous expression with only small patchy foci observed in 5% of the tumor cells, retaining a membranous expression score of 1: “low”. (e) Area from a grade 3 LUAC with a solid predominant histological pattern showing complete loss of membrane staining of β-catenin, in the presence of the intact membrane staining of the by standing bronchial epithelium as internal positive control. (f) Dedifferentiated area morphology of a pleomorphic LUAC with sarcomatous spindle cell exhibiting complete absence of β-catenin membranous expression and consequently scored 0: “lost”. Magnification ×100.