There are many clusters of lymph nodes already distributed under the fossa. Infectious diseases, tumor diseases, etc. may cause enlargement of lymph nodes here. 1. Infectious diseases, such as bacterial, viral infection or tuberculosis, the infection can spread with the lymphatic vessels, which leads to lymph node enlargement. Bacterial culture and drug sensitivity test should be performed, and appropriate antibiotics, antiviral drugs and anti-tuberculosis drugs should be given to treat the symptoms. 2. Oncological diseases such as lymphoblastic leukemia and lymphoma may be manifested by the appearance of multiple lymph nodes in the axilla, accompanied by generalized fatigue and fever, etc. Pathological biopsy should be performed to identify the disease. Pathological biopsy should be carried out to clarify the nature of the disease, and then bone marrow transplantation or radiotherapy and other comprehensive treatments should be carried out. In addition, breast cancer, lung cancer, thyroid cancer and other malignant tumors can also appear axillary lymph node enlargement through lymphatic metastasis. Surgical resection and radiotherapy (e.g. vincristine, cisplatin, etc.) should be carried out in time after clear diagnosis. It should be noted that when more than one lymph nodes appear in the axilla, one should go to the hospital in time for examination and treatment under the doctor’s guidance.