Evaluation of Mast Cell Distribution in Oral Lichen Planus and Lichenoid Lesions by Immunohistochemical and Histochemical Analysis

The histopathological assessment of Oral Lichen Planus (OLP) and oral lichenoid lesions is relatively subjective. The distinguishing criteria established by WHO effectively reproducible when all selection criteria were fulfilling but sometimes fail to provide a reliable diagnosis. The aim of the present study was to evaluate mast cell counts and their distribution among OLP and lichenoid lesions. The density and localization of mast cells was examined in 22 patients with a diagnosis of OLP (11 patients) or oral lichenoid reactions (11 patients) by c-kit/CD117 immunohistochemical and toluidine blue histochemical staining. Data were analyzed using either the Kruskal-Wallis or Mann-Whitney U tests. No significant difference in the total number of mast cells was observed between the two groups (P = 0.599); however, a significant difference was observed in mast cell counts between reticular and junctional zones (P<0.05). The findings of the present study suggest that mast cells play a key role in the pathogenesis of oral inflammation; however, the ability of mast cell measurements to reliably differentiate between lichen planus and other lichenoid mimickers was limited as the number of mast cells was found to be increased in both the conditions.