Hard lumps in the breasts may be caused by milk blockage, and the possibility of diseases such as breast hyperplasia, breast fibroadenoma, and breast cancer should also be considered. When breastfeeding, blockage of milk ducts and accumulation of milk may occur, resulting in hard lumps in the breasts accompanied by a feeling of swelling and pain. In addition to this, other breast disorders can also present with the symptom of hard lumps in the breasts. If you are not breastfeeding, have breast pain as the first symptom, and the breast lump may increase or decrease in size with the menstrual cycle, then it is mostly considered as breast hyperplasia. If the surface of the breast lump is smooth, easy to push, and the texture is elastic like a leather ball, and it is not accompanied by other uncomfortable symptoms, then it is mostly considered as breast fibroadenoma. If the breast lump occurs in the upper outer quadrant of the breast, the surface is not smooth, the boundary with the surrounding tissues is not clear, and it is not easy to be pushed, then it is mostly considered as breast cancer. At the same time, mastitis and breast trauma can also present with hard lumps in the breast. Hard lumps in mastitis usually show swelling and pain, and when the inflammation reaction is intense, the patient will have fever, redness, swelling and heat pain in the breast; while lumps formed by breast trauma, first of all, there is a history of trauma, and it also shows swelling and pain in hard lumps, so it needs to be carefully differentiated. The specific cause of the disease is recommended to consult a doctor for examination and diagnosis by a specialized doctor.