Analysis of micronuclei in exfoliation cytology of oral leukoplakias

Objective: To evaluate the presence of micronuclei (MN) in cell samples obtained by exfoliative cytology diagnosed as oral leukoplakia. Methods: The exfoliative cytology slides of 49 patients of the Pathology Laboratory of the Dental School of Positivo University were reviewed during the period of April 2002 to July 2006. These patients presented leukoplakia lesions in different anatomical sites in the mouth. The analysis of micronuclei was performed with a light microscope (objective with magnification of 100×) and was classified in seven categories. Counting was performed in 1,000 cells for each specimen using an image analyzer.The results were statistically analyzed using the Kruskal-Wallis test with a significance level of 5%. Results: The results showed little variation among the specimens in relation to the number of micronuclei, which ranged from zero to six micronuclei per sample. The only significant differences found in the number of micronuclei were perceived when comparing moderate atypia and severe atypia and moderate atypia and well-differentiated squamous cell carcinoma. Conclusion: The presence of micronuclei in oral mucosa suggests only a risk factor for development of oral cancer and is not an effective criterion for discriminating the histopathological or cytological diagnosis or prognosis of oral leukoplakia.