Lumps in the armpit can be seen in the following causes: 1, women are common in the paratesticular breast, that is, women’s breast development in the armpit has a paratesticular breast, and the normal breast tissue is the same, do ultrasound it and the structure of the breast tissue is the same, and sometimes it will happen at the same time with breast pain, for example, before menstruation, it can show the symptoms of distension, pain; 2, axillary lymph node enlargement: the axillary lymph node enlargement can be seen in the Lymphadenitis, i.e. inflammation in the corresponding reflux area of lymph nodes in this region of axilla, such as mastitis, axillary lymph node metastasis is also manifested as swollen lymph nodes, which is commonly seen in patients with malignant tumors, such as nasopharyngeal carcinoma, esophageal carcinoma, lung carcinoma and gastric carcinoma, which can be manifested as swollen lymph nodes in the axilla. According to different manifestations, after professional doctor’s consultation and treatment, a clear answer can be given, whether it is paraneoplastic breast, lymphadenitis, or a metastatic lesion of lymph nodes. Depending on the cause, the treatment and manifestation are different. If it is paratesticular breast, which seriously affects the beauty and appearance of the body, surgery can be considered; if the paratesticular breast is relatively small. It can also be kept under observation. If it is lymphadenitis and lymph node metastasis, corresponding treatment strategies are needed.