Circumferential hyperdensity in the left hilar region may be caused by lung inflammation, tuberculosis, lung cancer, etc. It can be treated by oral amoxicillin, isoniazid and other medications or surgery. 1. Lung inflammation: Inflammation of the left hilar region of the lungs caused by bacterial or viral infections will result in inflammation of the lungs, which will lead to pathological changes such as exudation and hyperplasia, thus leading to a ring-shaped hyperdense shadow at the left hilar region. You can take amoxicillin, cefixime and other drugs as prescribed by the doctor. 2. Tuberculosis: When Mycobacterium tuberculosis attacks the left hilum, it will also cause changes in the left hilum, resulting in inflammatory exudation and tissue necrosis, which will lead to a ring-like hyperdense image in the left hilum. Anti-TB drugs such as isoniazid and rifampicin can be taken orally as prescribed by doctor. 3. Lung cancer: Lung cancer can form a mass in the left hilar area with different density from normal lung tissue, which is manifested as ring-shaped hyperdense shadow in the left hilar area. If the patient’s lung function is good, it can be treated by surgery, combined with radiotherapy, immunotherapy and targeted therapy. If the patient has good lung function, he can be treated with surgery, radiotherapy, immunotherapy and targeted therapy. If the patient has a ring-shaped hyperdense shadow at the left hilar area, he should go to the hospital in time, complete the examination, and give targeted treatment after clarifying the cause of the disease.