A round ball in the breast that moves around may be caused by breast lymph nodes, breast hyperplasia, breast fibroma, other breast tumors and so on. 1. Breast lymph nodes: lymph nodes will increase in size when stimulated by inflammation and may move, and there is pain when inflammation is severe. 2. Breast hyperplasia: when endocrine disorders occur in the body, it will lead to hormone imbalance, which will lead to breast hyperplasia and form nodules, which are painful when pressed. 3. Breast fibroma: fibroblasts in the mammary gland are abnormally sensitive to estrogen, which is a common benign tumor of the breast. 4. Other breast tumors: such as breast lipoma, breast lobular tumor, sarcoma, lymphoma, etc.. The specific situation needs to be examined by breast ultrasound, molybdenum target and other examination programs for breast lesions. Therefore, when abnormalities occur in the breast, you should consult a doctor in time to clarify the cause of the disease, symptomatic treatment, and regular review.