• Etiology: transient collection of interstitial air due to Staphylococcus pneumonia (necrotic bronchi), blunt thoracic trauma, positive pressure ventilation, hydrocarbon ingestion
  • Imaging: has thin wall, usually no air-fluid level in infectious cases, occurs later in infection
  • DDX: abscess
    — Abscess appears earlier in infection, has thick irregular walls, lasts long time
    — Pneumatocoele occurs later in infection, has thin wall, usually no air fluid level

Cases of Pneumatocele

CXR of pneumatocele
CXR shows a large thin walled cystic lesion in the left lower lobe.
CXR and CT of pneumatoceles
CXR AP shows patchy airspace disease in the right lung. Axial CT with contrast of the chest shows right-sided airspace disease as well as thin-walled cysts with fluid-fluid levels.