Axillary lymph nodes are the lymph nodes located in the armpit. The neck, armpits, and groin are all areas of the body where lymph nodes congregate, making the lymph nodes under the armpits susceptible to lesions. The swollen lymph nodes under the armpits or the symptoms may be lymphadenitis, benign lymph node hyperplasia, lymph node tuberculosis, lymphoma or metastatic cancer, etc., which should be further clarified by physical examination and auxiliary tests. If the lymph nodes have soft texture, clear borders, good mobility, and the lymphatic gate is clearly visible on ultrasound, oval in shape, and the aspect ratio is less than 1, benign lymph node hyperplasia is most likely to be considered, and can be observed on regular ultrasound follow-up. For acute pain and redness of the skin of the mass, it may be acute axillary lymphadenitis, which should be treated with sensitive antibacterial drugs, and local magnesium sulfate can be applied as a wet compress. If an abscess is formed, an incision and drainage is required. In the case of lymph node tuberculosis, systemic anti-tuberculosis treatment should be given, and other tuberculosis lesions should be identified. For lymph node metastases, most of them are hard lymph nodes with unclear borders and poor mobility, and ultrasound shows that the lymph gates have disappeared and the aspect ratio is greater than 1. In the case of lymphoma, it can be further clarified by surgical blood test or ultrasound localized puncture biopsy.