Left lung cord shadows are the result of imaging tests, usually old scarring, but also may be caused by pneumonia, tuberculosis and other diseases. 1. Old scarring: Imaging findings suggesting left lung striae are usually the result of scarring left over from a previous lesion, forming a simple old striae in the left lung, which is usually asymptomatic. If the shadow does not change significantly in the follow-up examination, it can be suggested that it is a scar left over from an old lesion. 2. Pneumonia: If the patient has inflammation in the left lung, the streaks will also appear on the imaging, and the patient will also have symptoms such as cough and sputum. If the inflammation is obvious, the patient will also have fever. If left untreated, the shadow may widen and enlarge. Through standardized treatment, the shadow can be reduced or subside. 3. Tuberculosis: If you have tuberculosis, you will also see streaks on imaging. Generally, after anti-tuberculosis treatment, the streaks will become smaller or disappear, or form a stable scar-like streak. If you find that the left lung has cords and stripes, you should have further examination to clarify the diagnosis and choose the appropriate way to deal with it.