There is a hard lump inside the chest, commonly due to the following reasons: First, the growth of body surface swelling: such as sebaceous cysts, lipomas, fibroids, etc., need to go to the hospital to check the ultrasound or CT for clarification, if considered as sebaceous cysts, need to perform surgery to remove them to prevent their breakage and infection. Secondly, trauma: local hematoma will be formed after injury, and it will be hard to touch, so you can check ultrasound for clarification. Thirdly, other: If it is a woman, it may be caused by breast enlargement, and can be clarified by mammography ultrasound. If it is the disease, do not worry too much and go to the hospital for regular review. For some women, it is due to localized growths such as fibroids or even breast cancer, so a puncture biopsy or excisional biopsy of the mass is needed to clarify the nature.