Pediatric Lung Abscess

  • Etiology:
    — Complication of necrotizing pneumonia
    — Gram positive cocci predominate
    — Consider gram negative bacilli and anaerobes in patient with aspiration
  • Imaging CXR: Cavitary lesion with air-fluid level within area of consolidation
  • Imaging CT: Thick walled cavity with air fluid levels after necrotic pneumonia that is spherical in shape and destroys lung
  • Imaging US: Moves with respiration which distinguishes it from pleural empyema
  • DDX: Pleural empyema
    — Abscess – Spherical in shape, destroys lung
    — Pleural empyema – Nonspherical in shape, displaces lung, split pleura sign, enhancing rim sign of pleura, obtuse angles to chest wall, thickened pleura
  • DDX: Pneumatocele
    — 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
  • DDX: Infected congenital pulmonary airway malformation and bronchopulmonary foregut malformation which often present with recurrent lung infections
    — Note: Consider repeat imaging after infection resolves in order to look for residual lesion
  • Complications:
  • Treatment: Usually responds to medical treatment
  • Clinical:

Radiology Cases of Lung Abscess

CXR of lung abscess
CXR shows a round cavitary lesion with an air-fluid level in the left upper lobe.
CXR and CT of lung abscess
CXR and axial and coronal CT without contrast of the chest shows a cavitary mass in the densely consolidated left lower lobe and a moderate left pleural effusion.
CXR and CT of lung abscess
CXR PA and lateral (above) show a large round cavitary lesion with an air fluid level in the right lower lobe. Axial CT with contrast of the chest (below) shows a large round intraparenchymal fluid collection in the right lower lobe with thick nodular walls and an air fluid level.
CXR and CT of lung abscess
CXR AP (above) shows two air filled cavities in the right upper lobe in an otherwise completely opacified right hemithorax. Axial CT with contrast of the chest (below) shows a large right pleural effusion, right lung consolidation and a cavitary lesion in the right upper lobe.