Pneumatocoele: thin-walled (< 1mm), gas-filledspace in the lung developing in associationwith acute pneumonia, usually staph, andusually transient
Cavity: gas-containing space in the lunghaving a wall > 1 mm thick
Cyst: thin-walled, air- or fluid-filled, with a wallthat contains respiratory epithelium, cartilage,smooth muscle and glands
Bleb: intrapleural cystic space, uncommon