Cytomorphological patterns of tubercular lymphadenitis revisited

Background: Tubercular lymphadenitis is one of the most common causes of lymph node enlargement in developing countries. Fine needle aspiration cytology (FNAC) plays an important role in diagnosing Tubercular lymphadenitis and prevents unnecessary surgical intervention. Aim: To study the cytomorphological patterns of tubercular lymphadenitis in our study population and correlate the bacillary load by acid fast staining with cytomorphological patterns. Materials and Methods: A total of 150 cases of cytological proven granulomatous lymphadenitis and cases without granuloma, but positive acid fast bacilli (AFB) on Ziehl Neelson (ZN) stain were included in our study. Cytomorphological patterns were categorized into four patterns. Pattern A - Epithelioid granuloma without necrosis, Pattern B - Epithelioid granuloma with necrosis, Pattern C - Necrosis without epithelioid granuloma with neutrophilic infiltrate. Pattern D - with numerous macrophages. Chi-square test was done to correlate cytomorphological pattern and bacillary load. A 2 x 2 analysis was done to test the degree of one hypothesis. A P < 0.05 was considered as significant. Results: Patterns and the number of cases observed are as follows: Pattern A - 29 cases, Pattern B - 84 cases, Pattern C - 34 cases. A distinct D Pattern with abundant foamy macrophages was seen in three immunodeficient patients. Positive ZN staining was seen in 81/150 54% of cases. The cytological patterns of AFB positive cases Pattern A: 6/29 (21%), Pattern B: 46/84 (55%), Pattern C: 25/34 (73.5%), Pattern D: 4/4 (100%) . Conclusion: FNAC is useful in diagnosing tubercular lymphadenitis. Maximum bacillary load was seen in Pattern C. A distinct D Pattern was seen in immunodeficient patients.