There is a small lump in the breast, consider that it may be caused by breast fibroma, breast hyperplasia, breast cancer and so on. 1. Breast fibroma: it is a common benign tumor, most of them have no obvious clinical symptoms, and the growth is not obvious, and some of the patients will increase rapidly during pregnancy and breastfeeding. 2. Breast hyperplasia: it is mainly caused by endocrine disorders in the body, and is often swollen and accompanied by pain before and during the physiological period. 3. Breast cancer: in early stage, due to the limitation of tumor and small tumor, it may be manifested as small lumps locally. And the border is not clear, poor mobility, with the aggravation of the tumor, the lump will gradually increase in size. If there is a small lump in the breast, it is recommended to go to the hospital in time, cooperate with the doctor to take the examination, and handle or treat it after clear diagnosis.