Study of mast cells in non-neoplastic skin lesions.

Sixty non-neoplastic skin lesions were studied for mast cells by toluidine blue stain. The highest numbers of mast cells were seen in the viral infections of the skin (50/mm2) and lowest number of mast cells in congenital diseases (17/mm2). Out of the cutaneous bacterial infections, highest numbers of mast cells were seen in leprosy (44/mm2) while in lupus vulgaris they were much less (37/mm2). In leprosy cases it was observed that as the lesions moved from indeterminate to both polar tuberculoid and lepromatous, the mast cell count increased. It could therefore be summarised that periodic follow-up of indeterminate and borderline lesions for mast cell count might help in predicting stability of lesions. In non-infectious squamous and papular lesions the mean mast cell count was 39/mm2. The highest numbers of mast cells in the non-infectious vesicular and bullous lesions were in bullous pemhigoid (57/mm2) and lowest in dermatitis (38/mm2).