Comparative study of Ki67 protein expression in oral lichen planus and leukoplakia

Oral lichen planus (OLP) is included in the category of potentially malignant diseases. Benign processes are differentiated from malignant ones by the nature of cell proliferative activity. The aim of the present study was the comparative study of proliferative activity in OLP and leuk oplakia cells, as well as the cells of oral squamous cell carcinoma.
Materials and methods. Biopsy specimens from 16 patients with OPL, 13 with leukoplakia, and 7 with oral squamous cell carcinoma were investigated. Immunohistochemical studies were performed using Ki67 monoclonal antibodies.
Results. The average Ki67 index in OPL cells was 9.3 ± 2.3 %. Proliferating cells were located exclusively in the basal epidermis layer. In leukoplakia cells, the average Ki67 index was 20.5 ± 6.1 %; the proliferating cells were located in the basal layer and lower parts of the spinous (suprabasal) layer of the epidermis. In squamous cell carcinoma, the average Ki67 index was 57.4 ± 2.04 %. Proliferating cells were located diffusely over all cell complexes from the lower to the highest layers of the epidermis. Differences in the proliferation level were significant for the leukoplakia/OPL pair (p = 0.003) and squamous cell carcinoma/OPL pair (p < 0.001), while for squamous cell carcinoma/leukoplakia pair the difference was not significant (p = 0.211).
Conclusion. The differences in the proliferation level and in the nature of the proliferating cell distributionin through the epidermis can be applied in the differential diagnosis of OPL and leuk oplakia.