A hard lump in the right breast at the age of six years and five months without pain may be the result of precocious puberty, breast enlargement, or lipoma. If pain occurs it may be due to the stimulation of the nerves and glandular tissues on the surface of the breast, which leads to the occurrence of pain. 1. Precocious puberty: It may be due to breast development caused by eating foods high in estrogen for a long time. It is recommended to take your child to the hospital to check the hormone level. After a clear diagnosis, then give targeted treatment. Usually, you should pay attention to not eat anti-seasonal food, eat less fried puffed food. 2. Mammary gland hyperplasia: It is also possible that the baby’s breast subcutaneous chronic inflammation caused by mammary gland hyperplasia, thus causing hard lumps in the breast. If the clinical symptoms are not obvious, you can observe regularly. If the symptoms are serious, surgical removal can be considered. 3. Lipoma: If lipoma appears in the breast area, it will cause hard lumps. You can consult a regular hospital doctor and undergo surgical excision treatment if necessary. Generally speaking, breast lumps do not hurt, you can first observe for a period of time, develop good dietary habits, if the lumps are slowly relieved, do not worry too much, if they grow slowly or the pain is obvious, then you need to go to the hospital in time for examination.