Mediastinal lymph node enlargement refers to enlarged lymph nodes in the mediastinum, which is inside the patient’s chest cavity, between the two lungs, and is divided into anterior, middle and posterior mediastinum. Normally, there are no enlarged lymph nodes in the mediastinum, but if there are enlarged lymph nodes, they are usually caused by tumor metastasis, for example, thyroid cancer can cause enlarged mediastinal lymph nodes, and lung cancer, esophageal cancer, and even gastric cancer can cause enlarged mediastinal lymph nodes. Therefore, if a patient finds enlarged mediastinal lymph nodes during the examination, further whole body examination is needed to find out the location of the primary tumor lesion.