Significance of Mast Cell Density and Distribution in Various Histopathological Lesions of Leprosy

Background: Leprosy also known as Hansen’s disease (HD), is a chronic infection caused by the Mycobacterium leprae. Mast cells in leprosy have been investigated in the recent past and are being examined as a basis for future studies. Materials and Methods: 119 leprosy cases and 14 control biopsies stained with toluidine blue were assessed for density and distribution of mast cells. 38 cases had undergone treatment. Results: Significantly higher mast cell count was obtained in the skin lesions of borderline lepromatous leprosy. On comparison with controls lower counts were observed in polar tuberculoid and indeterminate leprosy whereas higher values were observed in all other groups. The mast cell count in leprosy is probably determined by the pattern of cytokines released by the T lymphocytes. Mast cell density assessed after treatment was reduced in borderline tuberculoid and borderline lepromatous cases however in indeterminate group, the counts were increased. Conclusion: The distribution of mast cells in leprosy is a variable feature and there is no constant site or predilection for a particular type of leprosy.