Old left upper lung lesions usually represent scars left by the absorption of inflammatory lesions in the lungs after treatment for pneumonia or tuberculosis in the past. Some patients may have had symptoms of coughing and sputum, but thought it was a common cold and did not have a chest x-ray or CT scan, and then went to the hospital for a CT scan or x-ray. If it is not a nodule or a mass, but just an old lesion or a shadow of a stripe, it represents a previous infection and does not need to be treated, so the patient does not need to panic, and the chest CT can be reviewed regularly in the future.