Fine-needle aspiration cytology of postvaccinial disseminated bacillus Calmette-Guerin infection.

Nine patients with primary immunodeficiency who received bacillus Calmette-Guerin (BCG) vaccine at birth developed disseminated BCG lesions and presented clinically with generalized skin rash and skin nodules. Fine-needle aspiration biopsy of the skin nodules and/or enlarged lymph nodes was performed in all patients. The most common cytologic pattern encountered was cellular smears showing a large number of histiocytes with abundant streaked cytoplasm in a background of neutrophils and debris. No granulomas were noted. Ziehl-Neelsen (ZN) stain for acid-fast bacilli showed a large number of these bacilli within the cytoplasm of the histiocytes, and extracellularly. This pattern was seen in 6 patients. The cytologic smears from 3 patients showed epithelioid granulomas in a background of neutrophils and debris. ZN stain for acid-fast bacilli showed fewer numbers of these bacilli compared to the first cytologic pattern. In conclusion, the most common cytologic pattern of postvaccinial disseminated BCG lesions in immunocompromised patients is a large number of histiocytes with abundant streaked cytoplasm in a background of neutrophils and debris. No epithelioid granulomas are seen in this pattern. A less frequent pattern is also encountered which shows epithelioid granuloma in a neutrophilic background. In both cytologic patterns, ZN stain for acid-fast bacilli is positive. However, in the first and most common pattern, the number of acid-fast bacilli is much larger than that seen in the second pattern. The different cytologic patterns might be related to the status of immunity of patients at the time of biopsy.