Bronchial atresia is thought to be a congenital abnormality.
A vascular insult occurring after the 15th week and before birth, could cause focal obliteration of a segmental bronchus with normal distal lung remaining. Secreted mucus collects distal to the closed bronchus and a bronchocele develops as a result of progressive mucoid impaction. Aeration of the segment occurs by collateral air drift via the pores of Kohn and the channels of Lambert. Air trapping and resultant hyperinflation may result from the collateral channels acting as check valves. Magnetic resonance imaging usually shows a bright branching structure in the lung parenchyma on T1 weighted images.