Fine needle aspiration cytology of reactions in leprosy.

OBJECTIVE: To define diagnostic cytomorphologic features of reactions in leprosy. STUDY DESIGN: Part-retrospective, part-prospective, single-blind, controlled study of the applicability of fine needle aspiration cytology in the diagnosis of reactions in leprosy. Cytomorphologic features were compared in 42 clinically diagnosed patients with reactions in leprosy with those in a control group of patients with nonreactional leprosy. The study groups included type 1 and type 2 reactions in 35 and 9 patients, respectively. May-Grünwald-Giemsa and Ziehl-Neelsen staining methods were employed. RESULTS: Statistically significant (P < .01) cytomorphologic features of type 1 reaction were the presence of fragments of collagen and elastin; giant cells; giant cells exhibiting elastin phagocytosis; loose, epithelioid cell granulomas; and fibroblasts. Type 2 reaction was characterized in aspirates by the presence of an abundance of neutrophils in a background of lepromatous leprosy (P < .01). CONCLUSION: Criteria that are used in histopathology for the diagnosis of leprosy reactions can be applied satisfactorily to cytologic smears. A good correlation between clinical diagnosis and cytomorphology can be achieved. Multiple-site aspirates from the skin, nerve and lymph nodes are helpful in substantiating the diagnosis.