Blebs or bullae are thin walled balloon-like extensions of air sacs. These sacs are believed to be caused by degradation of elastic fibers in the lung due to inflammation.

blebs and bullae are common among the general population, and when patients are examined by physicians, they are usually noted as being present on both lungs. Patients exhibiting such blebs traditionally have no history of lung disease.

The reason for the high incidence of spontaneous pneumothorax among tall males presenting with apical bullae is not completely understood. However, many feel that the morphology and physiology of tall men is such that they have an inherent defect in their structure which is manifested by a lengthened chest cavity and lung. This structure makes the lung apex more vulnerable to gravitational and other stresses which may cause bleb formation and a subsequent spontaneous collapse of the lung.


Thoracoscopic image of multiple apical bulla in patient with spontaneous pneumothorax.


Thoracoscopic image of apical blebs in patient with spontaneous pneumothorax.

External links:
http://en.wikipedia.org/wiki/Bleb
http://en.wikipedia.org/wiki/Bleb_(cell_biology)