Most of the patchy hyperdense shadows in the upper lobe of the left lung are caused by inflammatory exudation and edema in the lungs due to lung infection, tuberculosis or immune system diseases, or fibrous scar foci left after the healing of the disease, and a very small portion of them are caused by left lung atelectasis due to centralized lung cancer in the left lung. 1. Lung infection: inflammatory infiltration and edema caused by pneumonia, bronchiectasis, pulmonary aspergillosis and other diseases, which can be manifested as patchy high-density shadow in the upper lobe of the left lung in imaging examination. 2. Tuberculosis: infiltrative tuberculosis or caseous pneumonia can be seen in the upper lobe of the left lung, the tip of the lung patchy high-density shadows, the fibrous scar foci left after the healing of tuberculosis can also be manifested as patchy high-density shadows. 3. Immune system diseases: rheumatic pneumonia, connective tissue disease can also cause inflammatory reaction and edema of lung tissue, which can be manifested as patchy hyperdense shadow. 4. Centralized lung cancer of the left lung: centralized lung cancer can compress or block the bronchial tubes of the left upper lung, causing pulmonary atelectasis, which is manifested as patchy hyperdense shadow. Patchy hyperdense shadow in the upper lobe of the left lung is recommended to go to the hospital for further consultation and diagnosis.