Histopathological findings in nerve biopsies from patients suspected with pure neural leprosy in two teaching hospitals in Mumbai in the period 2008-2015

Summary Patients presenting with ‘pure neural leprosy’ poses a diagnostic challenge as several other peripheral neuropathies present with similar clinical features. It is common for patients presenting with peripheral neuropathy symptoms to seek treatment at the tertiary care hospitals. We report histopathological findings in 113 referred cutaneous nerve biopsies from patients suspected with ‘Pure neural leprosy’ at two teaching tertiary care hospitals in Mumbai, during the period 2008–2015. Confirmatory evidence of leprosy in histopathology was found in 83 (73·5%) cases and 35 (42·2%) among them scored positive for Acid-Fast Bacilli (AFB). Among the confirmed cases, the entire spectrum of leprosy was seen with predominance of Borderline Leprosy to Lepromatous Leprosy (BL-LLs) lesions (37·3%) followed by Borderline Tuberculoid (BT) (31·3%), Mid Borderline (BB) (15·7%) and Indeterminate type (4·8%). In the remaining 39 cases (34·5%), the nerves showed moderate to severe fibre loss but no specific infiltrating cells or AFB. Thus a conclusive diagnosis of leprosy could not be made.
Conclusion: Neural histopathology in almost 35% of suspected ‘pure neural cases’ did not conform to leprosy. The present study underscores the importance of  histopathology in establishing a firm diagnosis and classification, and draws attention to appropriate selection of nerve for biopsy.