A hard thing in the chest may be a physiological lump, acute mastitis, cystic hyperplasia of the breast, fibroadenoma of the breast, breast cancer and so on. 1. Physiological lumps, most often seen during puberty, estrogen levels increase, appearing breast hard lump-like changes, is a normal physiological phenomenon, do not need special treatment. 2. Acute mastitis, most common in breastfeeding women, is an acute purulent infection of the breast tissue, with only breast swelling and pain in the early stage and the formation of hard lumps in the breast, accompanied by localized elevated skin temperature. 3. Cystic hyperplasia of the breast, which occurs in women of childbearing age, is characterized by periodic pain in the breast and the formation of hyperplastic nodules. The degree of pain and the size of the nodules change with the menstrual cycle, i.e. it is aggravated during menstruation and relieved after menstruation. 4. Breast fibroma, which is more common in young people, manifests as a lump in the breast and can be painful. On examination, the surface of the lesion is smooth, with clear boundaries and good mobility. 5. Breast cancer, with no obvious characteristic performance in the early stage, in the late stage, irregular shape, hardness, poor mobility of the lump can be touched in the breast, and may be accompanied by orange peel sign or dimple sign. It is recommended to consult the hospital in time when there is a hard lump in the chest, and standardize the examination and treatment.