Pulmonary bulla (pulmonary bulla) is a large alveolar change caused by the rupture and fusion of alveolar walls due to elevated intra-alveolar pressure, usually caused by a live valve obstruction of small bronchi. There are congenital and acquired forms of pulmonary maculopathy. The congenital form is mostly seen in children due to congenital abnormal bronchial development, flap-like mucosal folds, and poorly developed cartilage, which causes valve action. Acquired is mostly seen in adult and elderly patients, often with chronic bronchitis and emphysema. In pediatric patients, it is most often seen in Staphylococcus aureus pneumonia, due to fine bronchial inflammation, edema, and mucus plugging, forming a local obstruction to the valve action. Due to fine bronchial inflammation, edema, and mucus blockage, the lumen is partially obstructed, creating a live valve effect that allows air to enter the alveoli but not easily expelled, resulting in increased pressure in the alveoli. Inflammation damages the lung tissue, and the alveolar septum gradually ruptures due to increased intra-alveolar pressure, and the alveoli fuse with each other to form large air-containing cavities. If the alveoli rupture and enter the dirty subpleural space, a subpleural blister is formed. There are single or multiple pulmonary blisters. Those secondary to pneumonia or tuberculosis are often solitary or have only a few blisters, and no obvious emphysema is present at the same time; those secondary to emphysema are often multiple, showing several large blisters with multiple small blisters, and the lung parenchyma surrounding the blisters is often associated with obstructive lung disease and emphysema. Pulmonary blisters are most often located in the apical and upper lobe margins of the lungs. Small pulmonary blisters themselves do not cause symptoms, and patients with simple pulmonary blisters are often asymptomatic; some pulmonary blisters may remain unchanged for many years, and some pulmonary blisters may gradually increase in size. The enlargement of pulmonary blisters or the appearance of new pulmonary blisters at other sites can cause pulmonary dysfunction and the gradual development of symptoms. Large pulmonary blisters can cause chest tightness and shortness of breath. The sudden enlargement and rupture of a pulmonary blister can produce a spontaneous pneumothorax, which can cause severe dyspnea and chest pain similar to angina pectoris. Patients with pulmonary blisters are often combined with chronic bronchitis, bronchial asthma, and emphysema, and clinical symptoms are also mainly caused by these diseases, only that they are further aggravated after the formation of pulmonary blisters. Secondary infection of pulmonary herpes can cause cough, cough, chills and fever, and in severe cases, cyanosis. If the draining bronchus is obstructed and the lung blister cavity is filled with inflammatory material, the cavity may disappear. It may occur clinically that the symptoms of infection disappear with treatment, while the pulmonary maculopapillary shadows on chest radiographs persist for weeks or months without resolving. Pulmonary signs are often a manifestation of preexisting lung disease. A chest x-ray is the best way to diagnose pulmonary maculoplasm. Apical pulmonary blisters appear as very thin, translucent cavities located at the edges of the lung fields and can be round, oval, or flatter rectangular in size, with transverse septa sometimes seen in larger pulmonary blisters. Multiple pulmonary blisters can be multifaceted when brought together. They are usually not in direct communication with the larger bronchi, have no fluid level, and are not accessible to bronchial contrast agents. Pulmonary blisters at the base of the lungs are often not easily seen on the orthopantomogram, some can be located completely below the level of the diaphragm apex, while others are only partially above the diaphragm apex. Giant pulmonary blisters are usually tense and may be surrounded by a layer of compressive atelectasis, making the wall of the blister appear thick and indistinct close to the chest wall. The nearby lung is pushed and causes partial atelectasis, with a clustered lung texture and reduced translucency. Pulmonary blisters may fuse with each other to form a very large, space-occupying pulmonary blister, resembling a confined pneumothorax. Pneumomediastinum may also rupture and produce a confined pneumothorax.