The nipple protrusion of a 10 and a half year old girl may be caused by physiological phenomenon, premenstrual syndrome or breast disease. 1. Physiological phenomenon: breasts and nipples are sensitive areas, stimulated by breast swelling and pain, breast protrusion and so on, is a normal physiological phenomenon. 2. Premenstrual syndrome: 10 and a half year old girls have entered puberty, by the body’s estrogen secretion, there will be sensitive nipple protrusion, breast swelling and pain and other phenomena. If the girl already has menstruation, it may belong to premenstrual syndrome. 3. Breast diseases: such as breast hyperplasia, breast fibroids, mastitis, etc., will cause the phenomenon of breast protrusion, if there is a large change in a short period of time, you need to consult a doctor in time. The 10-year-old girl’s breasts protruded a little phenomenon, it is recommended that parents should pay attention to, as soon as possible to take the child to the hospital to do the relevant examination and treatment.