Table 1.

Features of cyst and cyst-mimicking lucencies [1]

Lesion	Definition
Cyst	A round parenchymal lucency interfaced with normal lung
	Thin wall (< 2 mm).
Emphysema	Permanently enlarged airspace distal to the terminal bronchiole without a wall
Cavity	A gas-filled space within consolidation, a mass or a nodule
	Typically thick walled
	Sometimes contains a fluid level
Bulla	An airspace (size > 1 cm) with a round focal lucency, bounded by a thin wall (< 1 mm)
Bleb	Small sized (< 1 cm), gas-containing space within the visceral pleura or in the subpleural area
Pneumatocele	A thin-walled, gas-filled space in the lung, caused by infection, trauma, aspiration of hydrocarbon fluid
Honeycombing	Subpleural, multiple cystic cluster, typically 3-10 mm in diameter with well-defined walls
	Suggestive of end-stage lung disease