There is increased recognition that some lung cancers arise from or are associated
with air-filled cystic spaces. Recognition of precursors is important because these
are often overlooked and because some of these cancers progress rapidly once a solid
component develops. A systematic review suggests that such precursors typically appear
as irregular air cysts; these should be distinguished from bullae and smooth round
cysts with paper-thin walls that are often seen incidentally with increasing age.
Such irregular cysts usually enlarge slowly before developing a ground glass or small
solid component or becoming multiloculated. Such change warrants careful surveillance;
continued progression of a solid component justifies intervention. Early intervention
is associated with good outcomes; survival markedly diminishes if resection occurs
when a more substantial solid component has developed.
