Introduction: Leprosy is a slowly progressive chronic granulomatous disease caused by Mycobacterium Leprae (M. leprae) and predominantly affects skin and peripheral nerves. Leprosy is a leading cause of physical disability in India and poses a major public health challenge for the country. Histopathological evaluation and demonstration of Lepra bacilli by special stain is gold standard for definitive diagnosis and subtyping of leprosy.
Aim: To study the common histological subtypes of leprosy on the basis of microscopic features and bacteriological index.
Materials and Methods: A cross-sectional study was conducted in the Department of Pathology at Dr. S.N. Medical College, Jodhpur, Rajasthan, India. The duration of the study was two years and 11 months, from January 2019 to December 2021. A total of 55 skin biopsies which were histologically diagnosed as different types of leprosy were included. Patients data of age, gender, skin examination and other investigations were collected from the requisition forms and analysed. After proper fixation and processing of biopsy samples, Haematoxylin and Eosin (H&E) stained sections were examined for epidermal atrophy, presence of grenz zone, granulomas, infiltrates of lymphocytes, histiocytes, foam cells, infiltration of nerves and adnexa. The sections stained with Fite-Faraco stain were studied for the assessment of bacteriological index. On the basis of microscopic features, cases were categorised into tuberculoid leprosy, borderline tuberculoid leprosy, indeterminate leprosy, borderline leprosy, lepromatous leprosy and histoid leprosy as per Ridley-Jopling classification and percentage is calculated for each category. Data was entered and analysed by using Microsoft Excel version 2008 and Statistical Package for Social Sciences (SPSS) version 23.0.
Results: The mean age of the study participants was 39.6 years. Male to female ratio was 2.92:1. There were 33 (60%) cases with erythematous lesions followed by 15 (27.27%) hypopigmented lesions and 7 (12.73%) nodules. Out of 55 there were 21 (38.18%) cases of tuberculoid leprosy followed by 11 (20%) cases of borderline tuberculoid leprosy, 8 (14.55%) cases of indeterminate leprosy, 6 (10.91%) cases of borderline leprosy, 5 (9.09%) cases of lepromatous leprosy and 4 (7.27%) cases of histoid leprosy. Bacteriological index was negative in 35 (63.64%) cases followed by 2+ in 6 (10.91%) cases, 5 (9.09%) had index of 4+, 4 (7.27%) cases had index of 3+, 3 (5.45%) had index of 1+, and 1 (1.82%) case had index of 5+ and 6+ each.
Conclusion: Skin biopsy is easy, simple, inexpensive and outpatient procedure which provides adequate material for confirmation of the clinical diagnosis and further management. Histopathological examination including microscopic features of H&E stained sections, along with assessment of bacteriological index on Fite-Faraco stained sections remain the gold standard for diagnosis and subtyping of leprosy cases.
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