For various reasons, the destruction of alveolar wall will lead to the fusion of two or more adjacent alveoli into a larger cavity containing air sac. In this cavity containing balloon, the lung texture disappears and the air content increases, so obvious bright areas, mostly round or quasi-round, are displayed on chest radiograph or lung CT, similar to bubbles.
Extended data
Types of pulmonary bullae
1, classified by quantity
Pulmonary bullae are single or multiple, emphysema is often multiple, and the boundary between pulmonary bullae and lung tissue with emphysema-like changes around them is often unclear. Single cases can be seen after infection, idiopathic, etc.
2. Classification according to etiology
Secondary bullae: Inflammatory lesions secondary to bronchioles, such as pneumonia, tuberculosis or emphysema.
Idiopathic pulmonary bullae: Some are caused by congenital genetic abnormalities, and many are idiopathic pulmonary bullae with unknown etiology.
3. According to morphological classification and its relationship with normal lung tissue.
Type I: narrow basal bullae protruding from the lung surface, with a narrow pedicle connected with the lung parenchyma. Type I is usually single, with multiple pulmonary bullae clustered together, which are common in the upper lobe of the lung. Pulmonary bullae are thin and easy to rupture to form spontaneous pneumothorax.
Type ⅱ: extensive basal superficial pulmonary bullae, located on the surface of lung parenchyma, between visceral pleura and lung tissue. Connective tissue septum can be seen in the cavity of pulmonary bullae, which can be seen in any lobe.
Type ⅲ: deep pulmonary bulla with broad base, similar in structure to type ⅱ, but deep in position, surrounded by lung tissue, extending to hilum of lung and visible in any lobe.
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