If there is a hard lump in the breast of an 8-year-old girl, you need to go to the hospital for an ultrasound examination to determine whether it is development. If it is clear that the breast nucleus is long under the ultrasound, you can consider it as development; if it is only fatty tissue or other localized lesions under the ultrasound, it can be ruled out as development, and a clear diagnosis will be given based on the actual examination of the ultrasound. If the breast development of 8-year-old girls belongs to the early sexual development, in addition to the color ultrasound examination of breast nucleus, it is necessary to combine with the bone age examination, that is, the orthopedic film of the left wrist joint to clarify whether the current development of the child’s height is affected. If there is no loss of height after the bone age examination, it is necessary to pay attention to diet and sleep in daily life. If there is a significant loss of height after the bone age examination, it is necessary to further check the level of sex hormones and growth hormone and other related tests to give further treatment.