Pulmonary cavities are thick-walled abnormal gas-filled spaces within the lung. They are usually associated with a nodule, mass, or area of consolidation. A fluid level within the space may be present. Plain radiography and CT form the mainstay of imaging.
According to the Fleischner Society, pulmonary cavities are defined as "a gas-filled space, seen as a lucency or low-attenuation area, within pulmonary consolidation, a mass, or a nodule" .
The cause of pulmonary cavities is broad. They may develop as a chronic complication of a pulmonary cyst or secondary to cystic degeneration of a pulmonary mass. They may enlarge or involute over time.
Pulmonary cavities may be the result of malignancy, infection, inflammation, or be congenital:
- cavitating malignancy
- pulmonary tuberculosis
- pulmonary bacterial abscess/cavitating pneumonia
- post-pneumonic pneumatocele: a thin walled pneumatocele is not really a cavity but when infected can be thick-walled
- septic pulmonary emboli
- other rare infections
- non-infective granuloma
- pneumatoceles (a thin-walled pneumatocele is not really a cavity)
- congenital (not true "cavity")
A helpful mnemonic is CAVITY.