FNAC of Bacillus- Calmette- Guerin lymphadenitis masquerading as Langerhans cell histiocytosis.

Bacillus Calmette Guerin (BCG) lymphadenitis is a well known entity. Disseminated BCG infection usually presents as generalized lymphadenopathy, skin rash and hepatosplenomegaly and at times, can pose a diagnostic challenge to clinicians. There are only a few published studies on the cytological findings of BCG lymphadenitis. In this letter we report the fine needle aspiration cytology (FNAC) of BCG lymphadenitis clinically masquerading as Langerhans cell histiocytosis (LCH). FNA smears showed sheets of foamy macrophages and many polymorphs in a dirty necrotic background with many macrophages as well as polymorphs showing negatively stained rod like structures within their cytoplasm. Zeihl Neelson stain revealed that these cells were heavily loaded with acid fast bacilli (AFB). In the index case, AFB were also seen within the cytoplasm of polymorphs, which has not been documented earlier in the literature.