The recognition of mycobacterial infections by intraoperative cytology in patients with acquired immunodeficiency syndrome.

In patients with the acquired immunodeficiency syndrome, mycobacterial lymphadenitis is characterized by the presence of numerous acid-fast bacilli within histiocytes. In Diff-Quik-stained cytologic preparations of such lymph nodes, performed during intraoperative consultations, the presence of mycobacteria is manifested by numerous negatively staining rod-shaped spaces intracellularly within histiocytes, as well as extra-cellularly in the background. Recognition of these characteristic "footprints," or "negative images," of mycobacteria can facilitate early diagnosis and treatment. The morphological characteristics that help to distinguish between Mycobacterium avium-intracellulare and Mycobacterium kansasii are also described.