Long underarm nodules are not necessarily a precursor to major diseases, they may be caused by lymph node inflammation, breast cancer, paratesticular breasts, superficial underarm swelling and other diseases. 1. Lymphadenitis: usually due to inflammatory lesions in lymph nodes caused by pathogenic bacterial infection, generally benign lesions, patients can use drugs such as cephalosporin and penicillin sodium under the guidance of doctors for treatment. For patients with lymph node abscess, surgery can be adopted for treatment. 2. Breast cancer: usually due to genetic, radiation, abnormal hormone levels and other factors, resulting in the proliferation of breast epithelial tissue out of control, resulting in the emergence of malignant tumors. If it is not treated in time, it may lead to the spread of cancer cells. Patients can be treated with surgery, radiotherapy and chemotherapy under the guidance of doctors according to their actual conditions. 3. Associate breast: It is caused by the displacement of normal breast tissue, which can be manifested as nodules in the axilla, and locally will show the same clinical symptoms as normal breast tissue, such as swelling and pain during menstruation. 4. Superficial axillary mass: including lipoma, fibroma, sebaceous cyst, etc. The former two can be closely observed if they are asymptomatic, and the latter is recommended to be surgically removed as soon as possible after discovery because of the possibility of infection. If you have long nodules in the armpit, please consider other reasons such as primary tumors in lymph nodes. Please consult a doctor for examination in time to clarify the cause of the disease and avoid delaying the condition which may lead to adverse consequences.