A hard lump in the breast before menstruation may be a normal phenomenon, but it does not exclude breast diseases such as cystic hyperplasia of the breast and breast cancer. 1. Normal phenomenon: before menstruation, the body contains more estrogen and progesterone, breast gland proliferation, one or both sides of the breast swelling and pain and lumps. Breast swelling and pain is usually obvious before menstruation and lessens after menstruation; breast hardness can also disappear after menstruation, and generally do not need special treatment. 2. Pathological factors: However, it is not excluded that breast lumps are caused by other diseases, such as cystic hyperplasia of the breast, breast cancer, etc., which can be manifested as breast lumps, and it is necessary to go to the hospital to do breast ultrasound and molybdenum target in time to exclude related diseases and to prevent further development of lesions. Therefore, when there is a hard lump in the chest before menstruation, you should go to the hospital in time, complete the examination, clarify the cause of the disease and then follow the doctor’s instructions for targeted treatment.