Definition: The pleural cavity is a cavity between the lung and the chest wall. Under normal circumstances, the pleural cavity is nearly closed and there is only a small amount of lubricating fluid in its cavity and no gas should be present. When gas enters the pleural cavity, a pneumothorax is formed. Classification: Pneumothorax often arises from trauma or spontaneously, which are called traumatic pneumothorax and spontaneous pneumothorax respectively. Traumatic pneumothorax is a pneumothorax that occurs when gas enters the pleural cavity due to trauma to the chest wall or lung, mostly with obvious exogenous factors. Spontaneous pneumothorax occurs without the influence of exogenous factors, and its endogenous etiology is mostly subpleural pulmonary herpes or large alveolar emphysema, when these two lesions rupture, the gas in the lung can enter the pleural cavity resulting in pneumothorax. Clinical: Subpleural pulmonary blisters are mostly seen in adolescents, mostly with a thin and tall body type, and are caused by congenital underdevelopment of the pleura on the lung surface or pulling during the healing of lung inflammation and formation of fibrous tissue scar, etc. Strenuous activities, coughing and sneezing can induce the occurrence of this type of pneumothorax. Symptoms: The symptoms of pneumothorax patients may include sudden dyspnea, chest pain, irritating cough, etc. When tension pneumothorax occurs, the patient usually has severe symptoms, and shock and death can occur rapidly if medical treatment is not sought in time. X-ray chest film is easy to diagnose pneumothorax, and a few of them can be masked by bones, so the value of CT for pneumothorax diagnosis is quite high at this time, and CT can also assess the lung condition and provide the necessary basis for subsequent surgical treatment. Treatment: Treatment of pneumothorax includes conservative treatment and surgical treatment. According to the amount of pneumothorax, pneumothorax can be divided into 3 categories: small amount of pneumothorax (<20%), medium amount of pneumothorax (20%-40%), and large amount of pneumothorax (>40%). The first episode of small pneumothorax can be treated conservatively, including bed rest, restriction of activities, phlegm, cough suppression and pain relief, etc. A medium to large amount of pneumothorax requires emergency closed chest drainage, that is, a drainage tube is inserted into the chest as soon as possible to drain the chest gas and reduce the compression of the lung. If there are repeated attacks of pneumothorax with medium or large volume, or if there are obvious pulmonary alveoli and rupture under CT, surgical treatment is required.