Subpleural nodular shadow refers to the limited small nodular shadow in the pleura found during CT examinations, which usually refers to the small nodular pathological changes formed by the local thickening of the pleura. These pathological changes are mainly due to the following reasons: First, the pleura is invaded by bacteria such as Mycobacterium tuberculosis, resulting in nodular changes of local macrophages and lymphocytes, commonly known as tuberculosis nodules. Second, nodular changes in the pleura formed under the action of certain tumorigenic factors, i.e. tumorigenic changes. Third, after the absorption of pleural effusion, abscess chest and other lesions, the residual fibrin stimulates the local pleural thickening, which can also form subpleural nodular changes. If the nodular shadow under the pleura appears, further chest X-ray, CT and necessary pleural puncture examinations, combined with the necessary enzymatic tests, are needed to clarify the diagnosis, and then chemotherapy, surgery and close observation will be performed after the diagnosis is clear.