Enlarged lymph nodes may be caused by two things: 1. It may be an infection of the soft tissues or organs or organs near the lymph nodes. If enlarged lymph nodes appear in the jaw or neck and are accompanied by pain, they are most commonly caused by acute upper respiratory tract infections, with acute pharyngitis and acute tonsillitis being the most common. If the lymph nodes in the groin are enlarged, it is common to see septic infection of the soft tissue around the groin, or bacterial infection of the lower leg or even the foot, such as dermatitis or nail fungus, or even tinea pedis combined with bacterial infection. 2. Lymph node enlargement due to lymphatic metastasis of malignant tumors, if the lymph nodes in the armpit are enlarged, it is most common to see malignant tumors of the breast through lymphatic metastasis. If the lymph nodes in the armpit are enlarged, it is most commonly caused by the lymphatic metastasis of malignant tumor of breast.