A 36-year-old HIV-positive man presents with persistent dry cough, fatigue, and low-grade fever. Physical examination shows marked pallor and respiratory distress. An X-ray film of the chest reveals diffuse, bilateral, interstitial infiltrates. Bronchoalveolar lavage demonstrates a foamy alveolar cast composed of small cysts (shown in the image). What is the most likely diagnosis?
Human papillomavirus infection
Pneumocystis carinii pneumonia
Answer 😀 Pneumocystis carinii pneumonia
P. carinii (now correctly termed P. jiroveci) causes progressive, often fatal
pneumonia in persons with severely impaired cell-mediated immunity and is one of the most common opportunistic pathogens in persons with AIDS. About 80% of all untreated patients with AIDS develop P. carinii pneumonia in the course of their illness.
The morphologic hallmark of P. carinii pneumonia is foamy alveolar casts composed of small cysts.
None of the other choices display a foamy appearance shown in the photomicrograph.