As mentioned earlier, there are many causes of swollen lymph nodes; infections, autoimmune, and tumor causes. What kind of swollen lymph nodes are the most important to be alert for? Painless lymph node enlargement is the most alarming. I always tell my patients that swollen lymph nodes are not afraid of pain, but of no pain. First of all, most of the swollen lymph nodes are caused by infection or autoimmunity, which is a manifestation of inflammation, and the reason why the lymph nodes are swollen at this time is to fight against bacteria and viruses, so of course they will become bigger. If these characteristics are present, the swollen lymph nodes are most likely caused by inflammation, and if there are other recent manifestations of infection, such as fever, cold or gingivitis, then in most cases the swollen lymph nodes are caused by inflammation. If there is no other clear cause for the painless lymph node enlargement, such as infection or tuberculosis, it is time to be alert to the possibility of lymphoma or other malignant tumors. If you can do a direct biopsy, it is most direct, if not, you can consider doing a lymph node ultrasound or PETCT to help us determine it.