What's with the bullae?

Pulmonary bullae are formed by the high expansion of alveoli and the rupture and fusion of alveolar walls, which are generally caused by valvular obstruction of bronchioles, and the formation mechanism is the same as emphysema, but the degree is heavier. The alveolar diameter of emphysema is larger than 65438±0cm, which occurs in lung parenchyma and is often accompanied by different lung diseases, such as chronic bronchitis and bronchial asthma, advanced silicosis or sarcoidosis, and some pulmonary bullae can also be seen in patients without lung and bronchial diseases. Pulmonary bullae secondary to pneumonia or lung abscess are more common in infants, with single and multiple cases. Due to inflammatory lesions and edema of bronchial mucosa, the lumen is partially blocked, resulting in valve function. Air can enter alveoli and is not easily discharged. The pressure in the alveoli increases. Due to the increase of the pressure in the alveoli, the alveolar septum gradually ruptures, forming a huge cavity containing air sacs, which is clinically called pulmonary bullae. Secondary to pulmonary tuberculosis, mostly single, without obvious emphysema. Secondary to emphysema, it is often multiple, with most bullae besides bullae.