Background: Cell-to-cell interactions of mast cells and eosinophils are important for defense against the allergen in various infectious diseases, stromal invasion and carcinoma process. These cells have been shown to play an important role in progression of the oral potentially malignant disorders into squamous cell carcinoma. Therefore, a histomorphometric study of eosinophils and mast cells in potentially malignant disorders and oral squamous cell carcinomausing congo red and Toluidine blue stains, respectively was carried out. Materials and Method: 10 cases each of histopathologically diagnosed mild dysplasia, moderate dysplasia, severe dysplasia, well-differentiated squamous cell carcinoma, moderately-differentiated squamous cell carcinoma and poorly-differentiated squamous cell carcinoma were selected. Each section was viewed under high power in 10 consecutive microscopic fields for counting of eosinophils and mast cells. Comparison of eosinophil and mast cell counts among different grades of dysplasia and stages of squamous cell carcinoma were assessed by both parametric one way ANOVA and non-parametric Kolmogorov-Smirnov test. Result: It was found that the eosinophil counts showed an increasingly significant correlation in progression of dysplasias while mast cells did not show any correlation with such progression. While at the invasive fronts in oral carcinomas, mean mast cell counts showed a significant correlation while no such correlation is observed on observing eosinophils. Conclusion: Thus, the present study concluded that, with progressive dysplasias, there was a correlating increase in eosinophils but not that of mast cells whereas in carcinoma sections, there appeared to be a correlating increasing mast cell counts with progression of the disease but not that of eosinophils.
