Pulmonary cysts in the posterior apical segment of the upper lobe of the left lung are generally not a serious condition. Lung cysts are abnormalities in the development of the lungs and can contain gas and fluid. They are usually not serious, but can become serious if inflammation causes the cyst to become pus-filled and the fluid flows into the bronchial tubes, leading to a lung abscess. Lung cysts are usually benign, but repeated infections of the cysts can damage lung function and cause bleeding and other symptoms. Lung cysts can usually be treated with thoracoscopic resection surgery, which is performed by making a surgical incision between the ribs to fully display the lungs so that the diseased tissue can be removed, and placing a drainage tube to guide the secretions and air out of the pleural cavity. After the surgery, patients should follow the doctor’s instructions for regular checkups to avoid infections and recurring cysts. Patients are advised to go to the hospital for diagnosis and treatment under the guidance of the doctor.