The main reasons for tertiary breast nodules with axillary lymph nodes include breast cancer with lymph node metastasis or enlarged lymph nodes after mastitis. 1. Breast cancer with enlarged lymph nodes means that the patient’s breast nodule at this time is invasive breast cancer, and the enlarged axillary lymph nodes indicate that the cancer cells have already metastasized to the axillary lymph nodes at this time. However, at this time, it is necessary to perform further breast imaging examination such as MRI, molybdenum target, and puncture biopsy on breast nodule and enlarged axillary lymph nodes to clarify the nature of the nodule. 2. Post-mastitis lymph node enlargement refers to breastfeeding patients with a history of mastitis, and axillary lymph node enlargement occurs when mastitis occurs, and the nodes at this time are also post-inflammatory nodes, which can be clarified by combining the biopsy, patient’s medical history, clinical manifestations, and further imaging tests. Patients with breast nodules combined with enlarged axillary lymph nodes should be seen by the breast surgery department in a timely manner for active management.