Lymph, also called the lymphatic system, is an immune defense system composed of lymphocytes, lymphatic vessels, lymph nodes and lymphatic organs in the body, such as the tonsils, spleen and thymus gland together. It is responsible for the body’s protection, such as local swelling after a person is injured, and the lymphatic system is used to remove excess local fluid and restore normal circulation. If there are bacteria or viruses, the lymph nodes can also play a defensive role, eliminating them and preventing the spread of infection. When an infection occurs, the lymph nodes can become swollen and painful, such as in the throat, nose, and ear infections like otitis media, which can cause swelling and pain in the lymph nodes in the neck, but after the inflammation disappears, the swollen lymph nodes will shrink naturally. In addition, if a tumor develops in the lymphatic system, it is also called lymphoma, which is a systemic disease. If the tumor is not diagnosed and treated in time, the tumor cells grow without restriction and may cause various distant metastases and systemic depletion. For example, patients may experience fever, night sweats, weight loss, and even cause liver or respiratory system lung, and even central nervous system to be affected. However, with timely diagnosis and comprehensive treatment, the vast majority of lymphomas can be completely controlled.