Enlargement of lymph nodes in the neck is considered to be caused by infection, autoimmune and allergic diseases, lymphoma, tumor metastasis and other etiologies. 1. Infection: Infection of lymph nodes, such as viral, bacterial, fungal and parasitic infections, may cause lymphadenitis, which manifests as lymph node enlargement in the acute stage, accompanied by painful symptoms, and may be movable. 2. Autoimmune and allergic diseases: including systemic lupus erythematosus, rheumatoid arthritis, Kawasaki disease, serum sickness and drug allergic reactions. They are usually characterized by mild or moderate painless lymph node enlargement. 3. Lymphoma: It is a malignant tumor in the lymphatic system, which will present with painless enlargement of multiple lymph nodes, such as Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. 4. Tumor metastasis: when there are malignant tumors in peripheral organs, they are metastasized through the lymphatic system, and there will be enlarged lymph nodes in the neck, such as thyroid tumors and tumors in the lungs and so on. It mostly manifests as painless lymph node enlargement, hard texture and poor mobility. There are many possible causes of enlarged lymph nodes in the neck, so you should go to the hospital for a complete examination, make a clear diagnosis and then treat accordingly.