A 48-year-old man with AIDS is admitted to the hospital with a fever of 38.7degC (103degF). The patient has a 2-week history of persistent cough and diarrhea. Laboratory studies show that the CD4+ cell count is less than 500/mL. A sputum culture reveals acid-fast organisms, which are fuher identified as Mycobacterium avium-intracellulare. This patient's pneumonia is characterized by extensive pulmonary infiltrates of which of the following cell types?
High-Yield Explanation
This pneumonia is characterized by an extensive infiltrate of macrophages. The proliferation of MAI and the recruitment of macrophages produce expanding lesions, ranging from epithelioid granulomas containing few organisms to loose aggregates of foamy macrophages. The other inflammatory cells listed are not characteristic of infection with MAI.