Mandating nerve biopsy: A step towards personalizing therapy in pure neuritic leprosy

Pure neuritic leprosy (PNL) accounts for 5% to 10% of leprosy patients who usually present with asymmetrical neuropathy in the absence of lepra bacilli on slit-skin smears. However, nerve biopsies in PNL lack appropriate categorization in current immunologic terms. We aimed to classify nerve biopsies according to the immune spectrum of leprosy and assess the role of histologic classification of nerve biopsies in treating PNL. Patients from two tertiary care referral centres were enrolled in this incident case study. Patients presenting with mononeuropathy and multiple mononeuropathies presumably with leprosy, without skin lesions, underwent nerve biopsy and slit-skin smear examination. Amongst 78 patients with mononeuropathy, 38 were diagnosed with leprosy on nerve biopsy. Leprosy was classified as tuberculoid in 16, lepromatous in 5 and borderline in 17 patients. Lepra bacilli were present in 15 biopsies. On comparing histologic subtypes with number of nerves involved clinically, a significant number of cases with single nerve involvement showed multibacillary (BB, BL or LL) histology and vice versa. Nerve biopsy helps in diagnosing patients presenting with PNL and aids in classifying it to customize the treatment for best results. Current treatment recommendations for PNL from WHO and National Leprosy Eradication Program are based on clinical assessment only, which are likely to result in inconsistent treatment and possibly relapse in cases where histomorphology shows disparity. Inclusion of nerve biopsy to guide therapy in patients with PNL is suggested.