Causes of subpleural dense patchy shadow in the upper lobe of the right lung include lung infection, tuberculosis, rheumatic immune disease, lung tumor and so on. 1. Lung infection: when virus, bacteria, mycoplasma, fungus and other causes of lung infection, inflammatory exudation and interstitial edema can be manifested as subpleural high-density patchy shadow on chest CT, and the inflammation and edema can be subsided after giving anti-infective treatment. 2. Tuberculosis: Mycobacterium tuberculosis infection of the lungs can cause inflammatory exudation and pulmonary edema, appearing as subpleural high-density patchy shadow, generally need regular anti-tuberculosis treatment. 3. Rheumatic immune diseases: Rheumatic immune diseases such as rheumatic pneumonia, rheumatic interstitial lung inflammation can also cause subpleural high-density patchy shadow, generally need to give hormone immunosuppressive therapy. 4. Lung tumor: simple high-density patchy shadow can not confirm the diagnosis of tumor, but does not exclude the possibility of tumor, further examination is needed to clarify. Subpleural high-density patchy shadow in the upper lobe of the right lung is recommended to go to the hospital for further diagnosis and treatment.