Quantitative analysis of eosinophils and mast cells in potentially malignant disorder and squamous cell carcinoma using special stains

Background: Oral squamous cell carcinoma (OSCC) develops from potentially malignant lesions. Cells of the immune system are comprised of lymphoid series and myeloid progenitor series cells. Mast cells (MCs) and tissue eosinophils are both granulocytes which come under the myeloid progenitor series of the immune cells system. Inflammatory cells are found to play a crucial role and therefore should be studied in detail using various simple histochemical stains. Aims and Objectives: To evaluate the presence and compare infiltration of MCs and eosinophils in potentially malignant disorders and OSCC using special stains. Materials and Methods: Twenty-five cases of previously diagnosed cases of OSCC, 13 cases of oral submucous fibrosis, and 12 cases of oral leukoplakia (50 cases) were retrieved from the archives. Congo red and toluidine blue staining were performed for eosinophils and MCs, respectively. Analysis was done using analysis of variance and independent t-test, and P ≤ 0.05 was considered for statistical significance. Results: The mean number of MC and eosinophils was more in OSCC when compared to potentially malignant disorders. There was a significant correlation between eosinophils and MCs in potentially malignant disorder and OSCC. Intact MCs were more in number in potentially malignant disorder than in OSCC, and the mean number of degranulated MC was more in OSCC than in potentially malignant disorder. Conclusion: Eosinophil chemo-attractant factor released by MC invites more number of eosinophils during tumor progression. MCs and eosinophils may serve as a novel therapeutic target for cancer treatment, and inhibiting their function may inhibit tumor progression. Eosinophils and MCs can be visualized using Congo red and toluidine blue stain, respectively, which is accurate and easy to perform.