Posterior mediastinal lymph node 1.5cmx1.1cm, enhancement of ring-shaped enhancement indicates that there is lymph node enlargement, the possible causes are: lymph node tuberculosis, lymphadenitis, lymphoma, malignant tumor lymph node metastasis and so on. 1. Lymphadenitis: lymphadenitis may be caused by the spread of infection in neighboring tissues, or reactive lymph node hyperplasia. 2. Lymph node tuberculosis: Mycobacterium tuberculosis can easily invade lymph nodes and cause lymph node enlargement. Patients usually have a history of tuberculosis and may be accompanied by symptoms of tuberculosis toxicity such as low-grade fever, night sweats, fatigue, and emaciation. 3. Lymphoma: lymphoma is a malignant tumor originated from lymphatic tissues, theoretically, it may develop in all lymphatic tissues of the whole body. In addition to enlarged lymph nodes, patients may also have systemic symptoms such as low-grade fever, emaciation and itchy skin. 4. Lymph node metastasis of malignant tumors: lymph node metastasis of malignant tumors will also be manifested as enlarged lymph nodes, for example, esophageal cancer, lung cancer and so on. It is recommended that patients should go to the hospital as soon as possible to consult the doctor to clarify the nature of the lymph nodes and give timely treatment.