Disease
Pneumocystis pneumonia
PCP: dry cough and hypoxia in AIDS
noo-moh-SIS-tis
High-yield clue
Insidious dry cough, dyspnea, and marked hypoxia with bilateral 'ground-glass' infiltrates in AIDS (CD4 below 200) is the classic PCP clue.
Overview
An opportunistic fungal pneumonia from Pneumocystis jirovecii, studied as an AIDS-defining illness with hypoxia out of proportion to the chest exam.
Classification
- Opportunistic fungal pneumonia syndrome
- Pneumocystis jirovecii
- AIDS-defining illness
- Alveolar infection
Lab & identification clues
- Silver (GMS) or immunofluorescent stain of induced sputum/BAL vocabulary
- Elevated LDH vocabulary
- Diffuse bilateral ground-glass infiltrate imaging vocabulary
Associations
- At-risk: AIDS with CD4 below 200 cells/uL and other immunosuppression
- Insidious dry cough with progressive hypoxia
- Hypoxia out of proportion to chest exam vocabulary
- Prevention at low CD4 counts is an immunology/public-health teaching point
Commonly confused with
- Bacterial pneumonia
- CMV pneumonia
- Tuberculosis
Frequently asked questions
What is Pneumocystis pneumonia?
An opportunistic fungal pneumonia from Pneumocystis jirovecii, studied as an AIDS-defining illness with hypoxia out of proportion to the chest exam.
What is the high-yield clue for Pneumocystis pneumonia?
Insidious dry cough, dyspnea, and marked hypoxia with bilateral 'ground-glass' infiltrates in AIDS (CD4 below 200) is the classic PCP clue.
What is Pneumocystis pneumonia associated with?
Pneumocystis pneumonia is associated with At-risk: AIDS with CD4 below 200 cells/uL and other immunosuppression, Insidious dry cough with progressive hypoxia, Hypoxia out of proportion to chest exam vocabulary, and Prevention at low CD4 counts is an immunology/public-health teaching point.
What is Pneumocystis pneumonia commonly confused with?
Pneumocystis pneumonia is commonly confused with Bacterial pneumonia, CMV pneumonia, and Tuberculosis.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.