Pulmonary cavities are gas-filled areas of the lung in the center of a nodule, mass, or area of consolidation. They are usually evident on plain radiography and CT. They are typically thick walled and their walls must be greater than 2-5 mm. They may be filled with air as well as fluid and may also demonstrate air-fluid levels.
According to the Fleischner society, pulmonary cavities are defined "gas-filled space, seen as a lucency or low-attenuation area, within pulmonary consolidation, a mass, or a nodule" 7.
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 3
- pulmonary bacterial abscess/cavitating pneumonia
- post-pneumonic pneumatocoele: a thin walled pneumatocoele is not really a cavity but when infected can be thick walled
- septic pulmonary emboli
- other rare infections
- non-infective granuloma
- pneumatocoeles (a thin walled pneumatocoele is not really a cavity)
- congenital (not true "cavity")
A helpful mnemonic is CAVITY.
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