Clinical and cytomorphological patterns of granulomatous inflammation and its correlation with Ziehl–Neelsen staining

Introduction: Tuberculosis (TB) is one of the leading causes of mortality and morbidity in India, and extrapulmonary cases from the lymph nodes account for one-fifth of the overall disease burden. TB is known for its varied clinical presentations as well as different sites (organs) of involvement. Fine-needle aspiration cytology (FNAC) plays an important role in diagnosing a significant number of cases which present as granulomatous lesions. Here, we study the cytomorphological and clinical presentation of swellings showing granulomatous pattern of inflammation and correlate them with acid-fast bacilli (AFB) positivity. Materials and Methods: A retrospective study of 3-years duration was done from January 2018 to December 2020 in a tertiary care hospital. Slides of 356 cases showing epithelioid granulomas on cytology were taken out. The clinical data were collected from patient requisition forms. All the available clinical and cytological findings were recorded. The slides were re-examined and characterized into specific patterns of granulomatous inflammation on the basis of predominant background population of cells, necrosis, and hemorrhage. These were correlated with the presence of positive AFB staining on Ziehl–Neelsen (ZN) stain. Chi-square test was used for comparison between groups and P < 0.05 was taken to be statistically significant. Results: The mean age of presentation was 25 years (ranging from 5 months to 75 years) with a slight female preponderance (male-to-female ratio being 0.9:1). The cervical lymph nodes were the most common site. The sites of presentation were varied. The aspirates were gray–white to blood mixed on gross and cytological examination in 186 cases (52.25%). On microscopy, the suppurative pattern was seen in 202 cases (56.74%) and necrosis was seen in 182 cases (51.12%). The AFB positivity on ZN staining was seen in 96 (26.96%) cases in FNAC smears. There was a significant association of positive AFB staining with younger age group (<25 years), larger sized swellings (>2 cm), fixed and matted swellings, longer duration of symptoms (>2 weeks), and absence of pain and fever. The whitish/purulent aspirates on gross examination as well as suppurative and necrotic patterns on cytomorphology on microscopic examination showed a highly significant positive correlation with AFB staining. Conclusion: The gross and microscopic patterns of suppuration and necrosis on FNAC in combination with clinical signs and symptoms are highly suggestive of TB. ZN staining on cytology smears is a very simple and useful investigation, especially in suppurative and necrotic patterns of cytology, for clinching an early diagnosis, which goes a long way in the management of tuberculosis.