Comparative analysis of cell proliferation ratio in oral lichen planus, epithelialdysplasia and oral squamous cell carcinoma

ABSTRACT

Background: Although oral lichen planus has been classified by the World Health Organization (WHO) as a potentiallymalignant disorder, such classification is still the target of much controversy. Aim: To evaluate the cellproliferation rate in oral lichen planus, comparing it to the rate observed in epithelial dysplasia and oral squamouscell carcinoma, aiming at indications which might indicate the potential for malignant transformation . Materialand Methods: Twenty-four cases of each lesion were submitted to the streptoavidin-biotin and AgNOR techniqueto evaluate the immunohistochemical expression of PCNA and the mean NORs/nucleus, respectively. Results:Positivity for PCNA was observed in 58.33% of oral lichen planus cases, 83.33% of epithelial dysplasia casesand 91.67% of oral squamous cell carcinoma cases. Chi-squared test showed that the number of positive cases forPCNA was significantly lower in oral lichen planus than in oral squamous cell carcinoma (p<0.05). No significantstatistical difference between oral lichen planus and epithelial dysplasia (p>0.05) and between the epithelial dysplasiaand oral squamous cell carcinoma (p>0.05) was observed. The mean NORs/nucleus in oral lichen planus,epithelial dysplasia and oral squamous cell carcinoma were 1.74±0.32, 2.42±0.62 e 2.41±0.61, respectively. Varianceanalysis (ANOVA) revealed significant statistical difference between oral lichen planus and the other studiedlesions (p<0.05). Conclusion: Oral lichen planus cell proliferation rate was less than in oral epithelial dysplasia andoral squamous cell carcinoma which might explain the lower malignant transformation rate (AU)