Keywords
Tuberculosis; Lymph node; Fine needle aspiration
Abstract
Introduction: Ziehl Neelsen (ZN) staining has been the mainstay for detection of acid fast bacilli. Multiple sputum smear screening is advised to increase the detection of pulmonary tuberculosis. A similar approach may increase detection in lymph node aspirates. This prospective, observational study was aimed to study the effect of staged approach on the detection of acid fast bacilli in ZN stained smears from fine needle aspirates of patients with suspected tuberculosis lymphadenitis.
Materials and Methods: 300 patients, in whom lymph node aspirates were performed with clinical suspicion of tuberculosis, or in whose aspirates tuberculosis was suspected on the basis of the following three reaction patterns-epithelioid cell granuloma, epithelioid cell granuloma with necrosis or necrosis only, were studied. Smears reported negative for Acid-Fast Bacilli (AFB) at routine reporting (Stage I) were rescreened by a first observer (Stage II). Negative smears were rescreened by a second independent observer (Stage III). In cases where no AFB was demonstrated, additional material, that is another smear if available (Stage IV), and/or re[1]aspirate from the same lesion (Stage V) were examined. Statistical analysis was done by applying Binomial Exact test at each stage.
Results: AFB positivity at stage I – 185/300; AFB positivity at stage II - 224/300 (p value = 0.001); AFB positivity at Stage III - 240/300 (p value = 0.119); AFB positivity at Stage IV - 263/300 (p value = 0.010) and AFB positivity at stage V - 273/300 (p value = 0.001)
Conclusions: A cascading staged approach improves AFB detection in aspirates from lymph nodes of patients with suspected tuberculous lymphadenitis. In AFB negative patients, yield of AFB can be increased by examining a second smear obtained from the same aspirate. Further increase in the AFB positivity can be obtained if repeat aspirates are examined for the presence of AFB. Combination of the above two has an additive incremental effect.
Citation
Arora A, Singh N, Arora VK, Bhatia A and Husain N. Effect of Three Simple Quality Assurance Measures on the Detection of Acid-Fast Bacilli in Ziehl Neelsen Stained Smears of Aspirates from Lymph Nodes. SM J Clin Pathol. 2017; 2(1): 1009