Correlation of cytomorphological patterns and acid-fast Bacilli positivity in tuberculous lymphadenitis in a rural population of southern India

BACKGROUND: One of the most common causes of lymphadenopathy in India is tuberculosis. It can be diagnosed by a minimally invasive procedure known as fine-needle aspiration cytology (FNAC), and thereby unnecessary surgical interventions are avoided. AIM: This study was undertaken to evaluate cytomorphological patterns of tuberculous lymphadenitis including human immunodeficiency virus-positive cases, to correlate the acid-fast Bacilli (AFB) positivity with cytomorphological patterns and also to find out overall AFB positivity. MATERIALS AND METHODS: In this study, a total of 212 cases of cytologically proven tuberculous lymphadenitis were retrieved and analyzed retrospectively between March 2012 and March 2015 for three different cytomorphological patterns (epithelioid granuloma without necrosis [pattern A], epithelioid granuloma with necrosis [pattern B], and necrosis without epithelioid granuloma [pattern C]) and bacillary loads on Ziehl-Neelsen stain (ZN) for AFB. RESULTS: Pattern A through C was observed in 40 (18.9%), 102 (48.1%), and 70 (33%) cases, respectively. AFB positivity was found in 2 (5%) cases of pattern A, 62 (60.8%) cases of pattern B, and 54 (77.1%) cases of pattern C. The highest percentage of AFB positivity (64.7%) was observed in aspirate containing purulent/pus and caseous/cheesy material. The overall AFB positivity was seen in 55.7% (118/212) cases. On grading of AFB positivity, Grade 1+ was observed in 29.7%, Grade 2+ was observed in 28.8%, and Grade 3+ was observed in 41.5% cases. CONCLUSION: FNAC is a sensitive, simple, convenient, safe, minimally invasive procedure to diagnose tuberculous lymphadenitis. Study of both cytomorphological patterns and ZN staining for AFB can improve the diagnostic yield. Regardless of the presence of granuloma, ZN stain must be employed whenever infective pathology is suspected.