A cavity in the lung is usually a cavity that has formed as a result of liquefied necrotic lung tissue. There are several causes of cavities in the lungs, the most common being tuberculous cavities. Tuberculosis cavities are usually thick-walled cavities and are often seen in young people, often accompanied by clinical symptoms such as low afternoon fever, night sweats, weight loss, or blood in the sputum or hemoptysis. Lung infections can also cause cavities in the lungs, most commonly lung abscesses that cause thick-walled cavities in the lungs, often with chills, high fever, cough, and coughing up pus. Malignant tumors in the lung can also cause cavities in the lung, with lung cancer being the most common, mostly eccentric cavities, and often with unclear borders and burr signs. Therefore, timely improvement of enhanced CT or bronchoscopy is needed for clarification.