Acid-fast bacilli in fine needle aspiration smears from tuberculous lymph nodes -: Where to look for them

OBJECTIVE: To analyze where acid-fast bacilli (AFB) are most often seen in smears prepared from tuberculous lymph nodes. STUDY DESIGN: Patients referred for fine needle aspiration cytology for evaluation of lymphadenopathy between March 1994 and June 1998 were analyzed. Only those cases clinically and therapeutically proven to be tuberculous were included in the study. RESULTS: Of 783 cases analyzed, 213 (27.2%) were tuberculous. Aspirates obtained were of three types: blood mixed particles, caseous material and pus. Five cytologic pictures were seen: epithelioid cell granulomas alone or with coexistent necrosis, AFB or both, and necrosis with AFB. AFB were most often seen in purulent aspirates, followed by caseous and least often in blood-mixed particles. Granulomas were most often seen when the aspirate was blood-mixed particles,followed by caseous and, least often, pus. CONCLUSION: AFB detection should be carried out on all suspected tuberculous patients. The relationship between the presence of granuloma and of AFB is inverse. The chance of finding AFB is highest in patients presenting with a cold abscess and yielding pus on aspiration followed by patients who yield caseous material on aspiration.