Lymph node enlargement that cannot be eliminated afterwards may be caused by chronic lymph node inflammation or lymph node enlargement after tumor metastasis. Generally, chronic lymph node inflammation is caused by acute infection of lymph nodes, which manifests as swollen lymph nodes without pain. If local lymph node enlargement is caused by tumor metastasis, surgical resection is needed to find the primary lesion of the tumor, such as metastasis of lymph nodes in the neck due to thyroid cancer or metastasis of lymph nodes in the axilla due to breast cancer.