Expression of beta-catenin in basal cell carcinoma.

Background beta-Catenin is a crucial member of the E-cadherin/catenin complex, which plays a major role in cell-cell adhesion. beta-Catenin is also known to be involved in signal transduction pathways. Many studies have demonstrated changes in the expression of beta-catenin in colorectal carcinomas, suggesting a role for beta-catenin in neoplastic development. Objectives Basal cell carcinoma (BCC) is a locally invasive tumour. The various subtypes show differences in biological behaviour. This study aimed to investigate the presence of differences in the immunoprofile of beta-catenin among histological variants of BCC. Methods Eighty BCCs were studied (32 nodular, 7 micronodular, 24 superficial and 17 infiltrative and morphoeic). Formalin-fixed, paraffin-embedded tissue sections were stained for beta-catenin using the avidin/biotin immunodetection technique. Results All the nodular BCCs showed membranous and weak cytoplasmic staining. Nuclear staining was seen in 15 of 32 (47%) cases, being stronger at the periphery of the nodules in 11 of 15 (73%) of these cases. In superficial BCCs the membranous staining was variable and cytoplasmic staining was increased. Nuclear staining was seen in 16 of 24 (67%) cases, being more notable at the periphery in 8 of 16 (50%) of these cases. All micronodular BCCs showed strong membranous staining, weak cytoplasmic and no nuclear staining. In the infiltrative and morphoeic BCCs membranous staining was completely lost at the advancing margins of the invading cell strands, with a marked increase in cytoplasmic staining; nuclear staining was observed in all these tumours. Conclusions The expression of beta-catenin varied between different types of BCC. Nuclear localization was most notable in the infiltrative and morphoeic variants, followed by the superficial variant, and seen least in nodular BCC. Its prominence at tumour margins suggests that this may be associated with more aggressive types of invasion.