Immunohistochemical expression of p53 and PCNA proteins in oral lichen planus and oral dysplasia

Background: Oral lichen planus (OLP) is a relatively common chronic inflammatory muco-cutaneous disease classified among the potentially malignant lesions of oral mucosa. The aim of this study is to investigate and compare the expression of p53 and PCNA proteins in oral lichen planus and epithelial dysplasia cases. Materials and methods:Formalin-fixed and paraffin- embedded blocks of 21 lichen planusand 21 oral dysplasia cases were referred to immunohistochemical (IHC) analysis for anti p53 and anti PCNA monoclonal antibodies. Results: The results showed that positive nuclear staining for p53 was found in 11/21 (52.4%) cases of lichen planus and 17/21 (80.9%) cases of dysplasia. Positivity for PCNA was observed in 18/21(85.7%) of oral lichen planus cases, and19/21(90.5%) of epithelial dysplasia cases. There was a statistically significant difference between the expression of p53 and PCNA proteins in oral lichen plauns cases and non- significant differences of either protein expression in oral dysplasia cases. No statistically significant difference of p53 and PCNA proteins expression between oral lichen planus and epithelial dysplasia cases was found. Moreover, there was no significant difference in P53 and PCNA expression with respect to the grade of epithelial dysplasia. Conclusion: The proportion of cases with positive p53 expression increased from lichen planus to dysplasia. These results may indicate an involvement of p53 in neoplastic transformation as well as in proliferative events PCNA, although the absence of p53 staining could be used to predict the outcome of potentially malignant oral mucosal lesions