Context: Mast cells are the major effector cells in immediate hypersensitivity through activation via the high affinity IgE receptor and FcxRI. Given the broad array of proinflammatory mediators secreted from FcxRI – activated mast cells and IgE elevation is seen in a majority of atopic and contact dermatitis patients. Mast cells are believed to be involved in the pathogenesis of atopic and contact dermatitis. Aims: The present study aimed at evaluating the mast cell count with respect to morphology, distribution and quantity in atopic and contact dermatitis cases. Settings and Design:Retrospective study in an urban tertiary care hospital. Material and methods: The study included a total of 50 skin biopsies and mast cell count was assessed in skin biopsies from patients with atopic and contact dermatitis. The tissues were fixed in 10% formalin, processed by routine paraffin embedding technique. The sections were stained with freshly prepared toluidine blue stain. The toluidine blue stained sections were evaluated for qualitative and quantitative aspects of mast cells. Mast cells were counted per field at 40 X magnification. Statistical Analysis Used: The test results were evaluated by student T test. Results: Mast cells were significantly increased in skin biopsies from patients with atopic and contact dermatitis with mean mast cell count 104.94/10 high power fields. The test results were statistically significant and the p value was (<0.005). Conclusions: This study has revealed the role of mast cells as effector cells in development of atopic and contact dermatitis.

Keywords: Mast Cells; Toluidine Blue; Atopic Dermatitis; Contact Dermatitis.