The common cases of bumps under the arm armpits are as follows: 1. The armpit lymph nodes are enlarged and round or oval to touch. The main role of lymph nodes is immunity and phagocytosis. When there is an infection in the body and pathogenic microorganisms invade, the lymph nodes will increase in size in a stressful manner and release lymphocytes to play an immune, phagocytic role. In addition, when malignant tumor cells metastasize to the lymph nodes, resulting in enlarged lymph nodes, it can be basically judged by doing ultrasound examination, and if necessary, it needs to be surgically removed and sent for pathological examination; 2. The manifestation of parametrial breast under the axilla, which can be touched bilaterally and is relatively soft to touch, can be accompanied by menstrual cycle with pain and discomfort or significantly enlarged, and can be surgically removed if it affects the normal beauty; 3. It may be axillary lipoma, lump It is soft to the touch, irregular in shape, and can be diagnosed by ultrasound. If it increases significantly or affects the beauty, surgery can be chosen; 4. Sebaceous cysts in the armpits are hard to the touch, painful when they become infected, and can form abscesses, which need to be surgically removed.