Context: Mast cells have a multifunctional capacity. Their role in immunity is well known. Mast cells act as local immune modulators with a capacity to co-ordinate between pro and anti-inflammatory response. Leprosy is classified on the basis of immune status of patients. Mast cells in leprosy have been examined in recent past and are being examined as a basis for future studies. Staining of mast cells by Toluidine blue is well documented. Use of Fite Faraco’s stain can have an additional advantage of staining bacilli and mast cells. Aims: 1. To study average number of Mast cells in various types of leprosy. 2. To study distribution of mast cells with reference to Acid Fast Bacilli. Methods and Material: Study included 65 skin biopsies of histopathologically diagnosed cases of leprosy. Sections were stained by Fite Faraco’s stain, viewed under 400X and mast cells were counted per mm square. Their distribution in various types of leprosy was recorded. Results: Among the patients studied the males outnumbered females by a ratio of 1.6 : 1. Significantly higher Mean Mast Cell Density (27.94) was obtained in Polar Tuberculoid leprosy (TT), lowest was found in Polar Lepromatous leprosy (LL). Maximum numbers of mast cells were distributed around granulomas and glands. However, finding both mast cells and bacilli in same structure was not a constant finding. Conclusions: The higher mast cell density in the immunologically strong group of patients is evidence of the role of mast cells in the activated immune response to M. leprae infections.

Keywords: Leprosy; Ridley-Jopling Classification; Mast Cells; Fite Faraco’s Stain; Mean Mast Cell Density; Immunity.