7-year-old girl breast lumps have many reasons: 1, early development. 8-15 years old is the time of breast development, there is also a part of the little girl is 8 years old before the development of the development of the breast may feel the lump, belongs to the early development of the situation, you can go to the hospital for the hormone level of the examination of the diagnosis, treatment accordingly. 2, lymphadenitis. The lymph nodes in the chest may be stimulated by the lymph nodes resulting in lymph node enlargement, the small ones can be cured by taking medicine and infusion of anti-inflammatory drugs and disappear. The big ones are hard to eliminate and need to be removed by surgery, and use scar removal drugs to get rid of the scars after the surgery.3, breast disease. For example, the body’s hormonal imbalance, endocrine disorders caused by breast hyperplasia, the more serious is cancer, should be highly vigilant, breast biopsy to determine the nature of the disease, treatment, if it is a malignant disease timely treatment to curb the occurrence of disease.