Correlation of various techniques in diagnosis of tuberculous lymphadenitis on fine needle aspiration cytology

Objective. To study the correlation of cytomorphological features in fine needle aspiration smears from patients suspected of having tuberculous lymphadenitis with Ziehl-Neelsen staining (ZN), auramine-rhodamine staining (ARS), and autofluorescence (AF). Methods. A total of 145 lymph nodes were aspirated, 3 air-dried smears were stained with Giemsa, Ziehl-Neelsen, and auramine-rhodamine stains, and 1 smear was wet fixed for Papanicolaou staining. Needle washes were incubated in Lowenstein-Jensen medium for culture. Papanicolaou and auramine-rhodamine stained smears were examined under fluorescent microscope using a blue excitation filter (450-480 nm). Results. Ninety aspirates were reported on cytomorphology as suggestive of tuberculous lymphadenitis. Smear positivity for Mycobacteria by Ziehl-Neelsen method was 26.67% (24/90), while positivity increased to 34.44% (31/90) by auramine-rhodamine and 42.22% (38/90) on autofluorescence. Culture was positive in 27.78% (25/90) aspirates. Using culture as the reference method, the statistical values of ZN, ARS, and AF were as follows: sensitivity 80.0%, 88.0%, 96.0%; specificity 93.85%, 86.15%, 78.46%; positive predictive values 83.33%, 70.97%, 63.16%; and negative predictive values 92.42%, 94.92%, 98.08%, respectively. Conclusion. There is a definite advantage of autofluorescence over Ziehl-Neelsen and auramine-rhodamine which is to detect Mycobacteria, being more sensitive as well as an inexpensive technique. Autofluorescence can be a useful addition to routine cytology for early diagnosis and effective treatment.