Fine needle aspiration cytology as an aid to diagnosis, categorization and treatment when pure neuritic leprosy presents as nerve abscess

BACKGROUND: Pure neuritic leprosy (PNL) usually presents with neurological symptoms without skin involvement. Fine needle aspiration can play an important role in the management of PNL cases presenting as nerve abscesses. AIM: To assess the role of fine needle aspiration cytology (FNAC) in diagnosing and categorizing PNL cases presenting as nerve abscesses in the absence of neurological symptoms. MATERIALS AND METHODS: Five patients with subcutaneous nerve related swellings without clinically evident neurological deficits were subjected to FNAC. As the cytological features were suggestive of nerve abscesses due to leprosy, Fite stain was performed in all cases. As none of the patients had any leprosy skin lesions, they were diagnosed as cases of PNL. Features like cellularity, caseous necrosis, presence or absence of lymphocytes, macrophages, epithelioid cells, granulomas, Langhans giant cells and nerve elements were analyzed with the bacteriological index, to categorize PNL according to the Ridley-Jopling classification. RESULTS: Based on the cytological features and bacteriological indices, 3 cases were cytologically categorized into tuberculoid (TT)/borderline tuberculoid (BT) leprosy and the other two, as BT/borderline lepromatous (BL) and BL leprosy respectively in spite of having similar clinical presentation. Based on the cytological diagnoses, category-specific treatment could be instituted with clinical improvement. CONCLUSIONS: The simple and minimally invasive FNAC procedure allows diagnosis and a reasonably accurate categorization of PNL presenting as nerve abscess and therefore, highly useful in its clinical management.