Focal lung pneumatosis

A focal lung pneumatosis is a pocket of air (pneumatosis) in the parenchyma of the lungs, larger than the alveolus. A focal lung pneumatosis can be classified by its wall thickness. Blebs or bullae are also known as focal regions of emphysema.
The terms above, when referring to sites other than the lungs, often imply fluid content.
Cysts are seen in about 8% of the general population, with an increased prevalence in older people. They may be part of the aging changes of the lungs, and cause a slight decrease in their diffusing capacity. The presence of multiple pulmonary cysts may indicate a need to evaluate the possibility of bullous or cystic lung diseases. Cavitation indicates workup for serious infection or lung cancer.
Bleb or bulla.
The most common disease causing blebs or bullae is chronic obstructive pulmonary disease (COPD). The pathophysiologic process in this case is emphysema, which is the breakdown of the walls of the alveoli.
Other conditions associated with lung bullae are:
Cyst.
A pulmonary cyst is not necessarily the same type of cyst seen in many cystic lung diseases. The cyst for example in pneumocystis pneumonia is not the same as the pulmonary cyst.
Cystic lung diseases include:
Incidental blebs and cysts.
A focal lung pneumatosis that is an incidental imaging finding such as on a CT scan, without suspicious findings (such as findings indicating any of the diseases listed above), generally does not indicate further follow-up.
Cavity.
Two infectious diseases that are commonly associated with cavities of lung tissue are "Mycobacterium tuberculosis" and "Klebsiella pneumoniae". The formation of cavities is due to tissue necrosis and creates an environment that allows the pathogen to expand in numbers and spread further.
In the absence of infectious symptoms, a lung nodule with cavitation is a suspected lung cancer.