Pulmonary streak shadow is usually a fibrous streak of increased density in the lungs when a lung imaging test is performed. It is often seen as a scarring lesion in the lung after a lung infection, and is often caused by bacterial infection, viral infection, or an old lesion left after a tuberculosis infection. Therefore, no special treatment is needed for this condition, and patients are advised to follow up with a chest CT every six months to a year, and to quit smoking, avoid strenuous activities, and avoid getting cold.