Swollen lymph nodes in the neck of 8-year-old children may be caused by lymphoma, lymphadenitis, leukemia and other reasons. 1. Lymphoma: the most common symptom is painless lymph node enlargement in the neck, which may be accompanied by symptoms of fever, excessive sweating and unexplained weight loss. 2. Lymphadenitis: If infection occurs in the neighboring tissues of the neck, such as the head and face, it can cause pathogenic bacteria to flow to the lymph nodes through the lymphatic vessels, resulting in lymphadenitis and lymph node enlargement. 3. Leukemia: When leukemia cells proliferate and infiltrate, it can be manifested as enlarged lymph nodes, enlarged liver and spleen, and pain in bones and joints. Parents are advised to take their children to the hospital in time to clarify the cause of the disease and standardize the treatment under the guidance of the doctor.