Clinico-pathological correlations of macular lesions in leprosy, using a new histological grading system

In macular forms of pauci-bacillary (PB) leprosy as the dermal infiltrate is less, greater precision in evaluation is needed both for diagnosis, and for assessment of the efficacy of treatment. With this in view, a new numerical grading system on a scale from 0-4, with intervening decimals, was recently published to describe each specific pathology of the dermal nerves and appendages. This retrospective study of smear negative macular lesions, has utilized this grading system for comparison and follow up. Fifteen new patients with PB macular leprosy (TT, BT) were divided into two groups – Group A without deformity (ten patients), and Group B with deformity (five patients). All the patients had pre-treatment scalpel biopsies. In the pre-treatment biopsies in Group B the average grade of dermal granuloma was 1.3 compared to 0.5 in Group A. Two patients in Group A who were given daily Rifampicin and Dapsone for five and six months respectively, showed marked reduction in the infiltrate. In many biopsies a linear serpiginous infiltrate (horizontal) was present in the superficial dermis. This new grading system is useful for quantifying the dermal pathology in PB macular leprosy, for comparison of duration of treatment, or evaluation of newer drugs in studies, and for assessing resolution of the lesion by the pathologist.