Evaluation of Cyclooxygenase-2 in Oral Lichen Planus Using Immunohistochemistry

Lichen planus is a relatively common chronic inflammatory autoimmune disease of unknown etiology. The World Health Organization has identified lichen planus as a potential precancerous lesion. Cyclooxygenase-2 (COX-2) is a key enzyme for inflammatory processes and cell proliferation. The increased expression of COX-2 in some chronic precancerous inflammatory diseases and malignant neoplasms of the upper aerodigestive tract suggests its role in the early stages of carcinogenesis of the head and neck and can show its potential as a prognostic factor and marker of altered behavior. The aim of this study was to analyze the COX-2 marker in the pathogenesis and biological behavior of oral lichen planus and oral lichen planus with dysplasia. The incidence rate of the COX-2 marker in the 50 samples of the pathology archive of Mashhad Dental School, Mashad, Iran, including 25 samples of oral lichen planus and 25 samples of oral lichen planus with dysplasia, was evaluated using immunohistochemistry in 2017. In this cross-sectional descriptive-analytical study, the Kruskal-Wallis and Chi-square statistical tests were used to compare the incidence of the COX-2 marker in the study groups. Based on the results of this study, there was no significant difference between the two groups of oral lichen planus and oral lichen planus with dysplasia in COX-2 staining pattern in the basal layer and connective tissue; however, it was significantly higher in the suprabasal layer of the lichen planus group with dysplasia than that of the oral lichen planus group. In terms of location, lichen planus lesions with dysplasia were more commonly observed in the buccal mucosa, and oral lichen planuslesions (without dysplasia) were more frequently noticed in lips. Based on the findings of the present study, it can be concluded that increased COX-2 expression is observed in oral lichen planus lesions, especially those with dysplasia. The presence of lesions in some areas of the mouth, such as the buccal mucosa, tongue, and border of the tongue, is also more associated with dysplasia.