Immunohistochemical expression of Bcl-2 and Ki-67 in oral lichen planus and leukoplakia with different degrees of dysplasia.

OBJECTIVES: Oral lichen planus (OLP) is a chronic inflammatory disease of unknown cause. Malignant transformation in OLP lesions may be favored by changes in the expression of proteins that regulate cell proliferation and apoptosis. This study aimed to investigate these issues by immunohistochemical staining for Bcl-2 and Ki-67 and by correlating histopathological findings in samples from lesions of OLP and leukoplakia with epithelial dysplasia.

METHODS: Data for patients with OLP or leukoplakia with moderate or severe epithelial dysplasia recorded during 2006-2011 were retrospectively reviewed. The study samples represented 37 subjects with OLP (n = 14), leukoplakia with moderate (n = 8) or severe (n = 6) epithelial dysplasia, and normal buccal mucosa (controls, n = 9). New sections were subjected to histological examination and immunohistochemistry for Bcl-2 and Ki-67 in the basal layer, suprabasal layer, and inflammatory infiltrate, respectively.

RESULTS: All basal layer sections stained either negative or positive in <10% of cells for Bcl-2 in OLP (92.9% and 7.1%, respectively) and control (77.8% and 22.2%, respectively) samples. In leukoplakia, 85.7% of sections indicated positivity in <10% of cells, and 14.3% indicated positivity in 10-26% of cells. Most OLP (42.9%) and leukoplakia (64.3%) sections stained positive for Ki-67 in >50% of cells. All suprabasal sections stained either negative or positive in <10% of cells for Bcl-2 in OLP (92.9% and 7.1%, respectively), leukoplakia (42.9% and 57.1%, respectively), and control (88.9% and 11.1%, respectively) samples. Suprabasal staining for Ki-67 was negative or positive in <10% of cells in OLP (14.3% and 85.7%, respectively), leukoplakia (7.1% and 92.9%, respectively), and controls (88.9% and 11.1%, respectively). Staining for Bcl-2 in inflammatory infiltrate in OLP was positive in 92.9% of sections.

CONCLUSIONS: Expression of Bcl-2 may play a dual role in tumor development and progression. Increased cell proliferation in the epithelium may present a predisposition to cancer in OLP. The expression of Ki-67 can be considered as an adjunct marker for proliferative activity in lesions with malignant potential. The prognostic value of these immunomarkers in the evaluation of precancerous oral lesions requires further investigation.