Cytomorphology in Tuberculous Lymphadenitis and Correlation With Acid Fast Bacilli Detection by Papanicolaou, Auramine-Rhodamine Fluorescence and Ziehl-Neelsen Techniques

Background

Tuberculosis (TB) is a common cause of lymphadenopathy in developing countries. Fine needle aspiration cytology (FNAC) along with acid fast bacilli (AFB) detection is an invaluable diagnostic test. Fluorescent methods for AFB detection have greater sensitivity as compared to the Ziehl-Neelsen (ZN) method.

Methods

The incidence of TB lymphadenitis was determined among all lymph nodes aspirated over 5 years, from January 1993 to May 1998 in an Indian referral hospital. Cytomorphological spectrum was studied in 234 smears, and AFB positivity was determined by Papanicolaou (PAP), Auramine-Rhodamine (AR) fluorescence as compared to the ZN method.

Results

Of a total of 6592 lymph node aspirates, 33.86% were diagnosed as tuberculosis; maximum patients were between 11 and 30 years (68.5%), with a female predominance. Cervical nodes were commonly involved (85.6%). Tuberculosis was diagnosed in 41.4% of the 55 patients diagnosed with HIV infection. Cytomorphology in 234 smears examined predominantly showed caseous necrosis with degenerating histiocytes (48.7%). PAP method was the most sensitive for AFB detection (73.1%), followed by AR (57.7%) and ZN (42.3%) and the rate of AFB detection and bacillary load increased with the presence of caseous necrosis and polymorphonuclear cells and decreased with epithelioid cells, presence of caseous necrosis being statistically significant (p < 0.05).

Conclusion

Incidence of tuberculous lymphadenitis is high in developing countries. FNAC along with AFB detection is a reliable and definitive diagnostic procedure. Fluorescent techniques are more sensitive than ZN method for AFB detection, with certain limitations. Further studies may need to be done to evaluate their diagnostic utility over ZN method.