A left lower lobe cords shadow suggests a history of chronic infectious disease in the left lower lung, with residual lesions formed during resorption. The number of cords can be used to assess the severity of the previous infection. In the case of tuberculosis infection, the presence of cords may be accompanied by pleomorphic changes, including proliferation, calcification, and nodular thickening, which may indicate previous tuberculosis infection. If pneumonia, bronchiectasis with infection, or lung abscess occurs in the left lower lung, the cords may also appear during the resorption process, which are mostly old lesions. If there are no clinical symptoms, no special treatment is needed, and only dynamic follow-up chest imaging is required.