- Etiology: gram positive cocci predominate, consider gram negative bacilli + anaerobes in patient with aspiration
- Imaging: spherical in shape, destroys lung, thick walled cavity with air fluid levels after necrotic pneumonia
- US: moves with respiration which distinguishes it from empyema
- DDX: pleural empyema
— Abscess – spherical in shape, destroys lung
— 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 / bronchopulmonary foregut malformation which often present with recurrent lung infections
— Repeat imaging after infection resolves to look for residual lesion
Radiology Cases of Lung Abscess

