The spectrum of cytological findings in patients with BCG lymphadenitis: A series of 13 cases.

CONTEXT: Bacillus Calmette-Guérin (BCG) vaccine has been used to prevent tuberculosis and/or its severe complications for long. BCG lymphadenitis is a common complication of the vaccine, which is sometimes subjected to cytological examination. The aim of the study is to describe the cytological findings of BCG lymphadenitis.

SETTINGS: The study was conducted in a tertiary care hospital in the western part of India from January 2021 to December 2022.

DESIGN: The study was performed on archived material of all patients who were referred to the fine needle aspiration clinic for cytology examination. Clinical and pathological data of cases were retrieved, and cases of BCG lymphadenitis were selected in the study based on these data. Slides of cases were retrieved, and cytological findings were studied.

MATERIALS AND METHODS: Papanicolaou, Giemsa, and Hematoxylin & eosin-stained smears, as well as Ziehl-Neelson stain (Z.N. stain) smears of all BCG lymphadenitis cases, were retrieved. Cases were reviewed for individual cytological features and overall cytological diagnostic categories. Z.N. stain smears were evaluated for acid-fast bacilli.

RESULTS AND CONCLUSIONS: Diagnostic categories observed in BCG lymphadenitis include suppurative lymphadenitis/abscess (15 %), necrotizing lymphadenitis (23 %), necrotizing granulomatous lymphadenitis (46 %), suppurative granulomatous lymphadenitis (8 %), non-necrotizing granulomatous lymphadenitis (8 %). Acid-fast bacilli were detected by Z.N. stain in 8 cases (62 %). The cytological findings of BCG lymphadenitis closely overlap with those of tuberculous lymphadenitis. So, clinical context is very important while reporting isolated axillary lymphadenopathy, specifically in recently vaccinated infants, to avoid misdiagnosis as tuberculous lymphadenitis.