Hard lumps and pain in the breasts of an 8-year-old girl could be breast development, also known as sexual development. To clarify whether it is caused by breast development or a localized swelling due to trauma, you need to diagnose it under ultrasound, and a mammography examination will clarify whether it is a gland or a hematoma. If a girl’s breasts develop before the age of 8, it can be diagnosed as precocious puberty, and precocious puberty girls will have two problems: first, they will have early menstruation; second, they may be short in height in the future. Early sexual development will lead to premature closure of the child’s epiphysis, thus the height will not grow in advance, and the symptoms of early growth will also appear. Once breast development occurs, in addition to ultrasound also need to do bone age test, that is, the left wrist joint orthopedic film to clarify whether the child (height) is lost, early intervention and early treatment, to avoid lifelong height is too short.