A small flaky shadow in the extra-basal segment of the left lower lobe of the lung is a description of an intrapulmonary lesion on CT, and the causes of the condition include inflammation, trauma, pulmonary embolism, and tumors. 1. Inflammation: the appearance of small flaky shadow with coughing symptoms, the first consideration of inflammation, need to be combined with clinical history to make a comprehensive judgment. 2. Trauma: trauma causes localized lung contusion, which may also cause pulmonary tissue exudation, resulting in corresponding changes, usually accompanied by chest pain. 3. Pulmonary embolism: if the coagulation condition is abnormal and the lesion is wedge-shaped, it may be caused by pulmonary artery embolism, and enhancement examination is needed. 4. Tumor: some early tumors may cause corresponding changes, and most of them will be continuously enlarged. If you find a small flaky shadow in the outer basal segment of the lower lobe of the left lung, accompanied by obvious symptoms such as cough and chest pain, you need to consult a doctor in time, and carry out standardized treatment under the guidance of the clinician after confirming the condition.