[To the question of proliferative verrucous leukoplakia malignant potential].

Aim Of Study: To study of neoplastic transformation of the epithelial cells of the oral mucosa with verrucous hyperortokeratosis, verrucous carcinoma and oral squamous cell carcinoma (OSCC).

Materials And Methods: Oral mucous membrane biopsies of 33 patients with clinical diagnosis of proliferative verrucous leukoplakia were investigated. Histologically in 19 cases (57.6%) was revealed verrucous hyperorthokeratosis, in 8 cases (24.2%) - verrucous carcinoma and in 6 cases (18.2%) - oral squamous cell carcinoma. Tissue antigens were determined using mouse monoclonal antibodies to Ki-67 and mouse monoclonal antibodies to cytokeratin 15.

Results Of The Study: In comparison with the proliferative activity of epithelial cells in the malpighian layer in verrucous hyperorthokeratosis (17.2±8.1%) was detected increasingof cell proliferation in epithelial growth zone in verrucous carcinoma (33.8±8.1%) and in peripheral zone of solid areas in oral squamous cell carcinoma (51.2±35.7%). A significant decrease in the expression of cytokeratin 15 in the cytoplasm of tumor cells was noted inverrucous carcinoma and oral squamous cell carcinoma in comparison with verrucous hyperorthokeratosis.

Conclusion: The obtained results proclaim that there is no stage of epithelial dysplasia during tumor transformation of proliferative verrucous leukoplakia into verrucous carcinoma and oral squamous cell carcinoma. Verrucous carcinoma by the nature of proliferative activity, cell atypia and expression of cytokeratin 15 corresponds to carcinoma in situ.