Secondary tuberculosis of the left upper lung is a pathognomonic diagnostic type of tuberculosis, mainly belonging to the third type of tuberculosis, including infiltrative tuberculosis of the left upper lung and chronic fibro-cavernous tuberculosis of the left upper lung, and is also the main type of the most common clinical source of infection. Clinically, it mainly presents with toxic symptoms of tuberculosis, such as persistent low-grade fever state, cough, sputum and hemoptysis, accompanied by wasting, weakness and loss of appetite. In addition, the left lung forms cavities with varying degrees of fibrosis and calcification. Due to the inflammatory infiltration of the left lung, it may also cause compensatory emphysema in the right lung on the opposite healthy side in more severe cases, with symptoms of wheezing, shortness of breath, and progressively increasing expiratory dyspnea.