Purpose: The aim of this study was to investigate the malignant potential of oral lichen planus (OLP) on the basis of the expression of the Bcl-2 marker in healthy individuals (H), patients with OLP and patients with squamous cell carcinoma (SCC), and to establish potential interdependence between expression of Bcl-2 and the different clinical and histopathological parameters in H, OLP, and SCC. Methods: Immunohistochemistry for Bcl-2 was carried out using an avidin-biotin peroxidase complex method. Tissue sections were treated with mouse monoclonal antibody against Bcl-2 (124, DAKO A/S, Denmark; dilution 1/100). Immunohistochemical parameters measured included total tissue area, total stained area and intensity of stain. Results: Keratinocytes were not Bcl-2 positive in H and were sparsely positive in OLP. The number of lymphocytes stained with Bcl-2 was significantly lower in Has compared to patients with SCC and OLP. Bcl-2 staining was weak to moderate in OLP, and moderate to intense in SCC. Bcl-2-positive lymphocytes were more expressed in older OLP patients (>55 years), and in OLP specimens with orthokeratinized epithelium, less developed acanthosis and highest grade of lymphocyte expression. Conclusion: Bcl-2 may not serve as a prognostic biomarker in oral cancer development from OLP, but it could help in selecting patients with higher need of follow up to prevent malignancy
