The chance of malignancy in breast nodules 4a is between 2% and 11%. Although breast nodules are mostly considered benign nodules, there is a certain risk of malignancy. If the results of two consecutive years of review show no abnormal lesions, observation and review can be done first. If the nodule grows too fast or exceeds 2 cm in size, immediate surgical removal and pathological examination are required. If the pathology is malignant, further treatment is necessary, including mastectomy, targeted drug therapy, radiotherapy and chemotherapy. In summary, although the malignancy rate of breast nodules 4a is not high, it is still important to be examined and treated promptly.