an air-containing space seldom exceeding 1-2 cm., subpleural and most frequently developing over lung apices. Development of blebs has been attributed to dissection of air over a ruptured alveolus, where it accumulates in the visceral pleura in the form of a cyst. Blebs basically represent paraseptal emphysema and are usually regarded as the major cause of spontaneous pneumothorax.
an abnormal pocket of air in the lungs, usually under the lining of a lung, that can rupture with ascent and lead to barotrauma.
a collection of air contained within the elastic fibers of the visceral pleura