Nodules in the upper lobe of the left lung can be seen in tuberculosis, pneumonia, malignant tumors and other diseases. 1. Tuberculosis: caused by infection such as Mycobacterium tuberculosis, granuloma will be formed during the disease and after cure, and it will be shown as nodules under imaging. 2. Pneumonia: caused by bacterial, viral, fungal infections, etc. Inflammatory exudation can lead to nodules in the upper lobe of the left lung if there is a history of pneumonia and bronchitis. 3. Malignant tumors: If the upper lung nodules show isolated nodules with non-smooth, burr-like edges, they are likely to be malignant and need to be diagnosed promptly by puncture biopsy. It should be noted that the upper lobe of the lung is the high incidence of tuberculosis and pneumonia, if there are manifestations of such diseases, it is necessary to carry out relevant examinations under the guidance of a specialized physician to rule out the diagnosis. If the nodules are small, and there is no fever, cough and other inflammatory symptoms, they can be reviewed regularly; if the nodules have a tendency to increase in size, it is necessary to confirm the diagnosis through enhanced CT, puncture biopsy and other ways, and then carry out targeted treatment.