Detecting mycobacteria in Romanowsky-stained cytologic smears. A case report.

BACKGROUND: Cytologic features of mycobacterial infections are granulomatous inflammation with or without caseous necrosis and the demonstration of acid-fast bacilli with special stains. However, immunocompromised patients might not mount the expected response. CASE: A routinely used Romanowsky (Leishman) stain was used for the presumptive diagnosis of mycobacterial infection in a 30-year-old man with AIDS. The mycobacteria were identified as inclusions, described as negative images, in the cytoplasm of macrophages in smears of bone marrow aspirate. They were then confirmed to be acid-fast bacilli with Ziehl-Neelsen stain. CONCLUSION: Negative images of mycobacteria may be seen in Romanowsky-stained cytologic smears from patients with immunodeficiency. This is a rapid and cost-effective way of detecting the mycobacteria before more specific results are available. Such a search should be undertaken routinely in all patients suspected to have such infections.