Bilateral, symmetric ground glass that is perihilar or upper-lobe predominant with peripheral sparing, sometimes crazy paving, sometimes thin-walled cysts — in an immunocompromised patient. Nodes, effusion or discrete nodules point elsewhere.
Orient first
- PJP affects people with HIV (CD4 < 200) and those on steroids, chemotherapy or transplant immunosuppression; non-HIV disease is faster and more severe.
- The radiograph may be normal early — CT is the sensitive test when suspicion is high.
- Cysts (pneumatoceles) are more common in HIV and predispose to pneumothorax.
Acquire the study
- Chest radiograph; non-contrast thin-section CT when the radiograph is normal or equivocal.
The manoeuvre
- Lung window, axial: bilateral, symmetric ground glass, perihilar or upper-lobe predominant; note subpleural (peripheral) sparing.
- Crazy paving (ground glass with septal thickening) and, later, consolidation.
- Cysts: thin wall, upper-lobe; pneumothorax on the lung window and coronal reformat.
- Atypical features that suggest another diagnosis: lymphadenopathy, pleural effusion, discrete nodules, tree-in-bud.
What confirms it
- Typical ground-glass distribution in a susceptible host, confirmed by PCR/staining of induced sputum or BAL.
What licenses you to exclude it
- A normal thin-section CT effectively excludes PJP in a symptomatic patient.
The classic misread
- Accepting a "normal" radiograph in a breathless immunocompromised patient — ask for CT.