It is not normal to have hard lumps in the breasts, which suggests that there may be breast hyperplasia, breast fibroadenoma, mastitis, breast cancer, trauma and other causes, and it is recommended to go to the hospital to find out the causes. 1. Breast hyperplasia: Normal breasts do not have hard lumps, but some women may experience breast hyperplasia before and after menstruation due to hormonal instability, which can be manifested as hard lumps in the breasts. 2. Mammary fibroadenoma: If the breast tissue is abnormally sensitive to estrogen, a fibroadenoma will form, which can manifest as a hard lump in the breast. 3. Mastitis: Non-lactating mastitis can be characterized by hard lumps in the breast due to inflammation, and in severe cases, abscesses can form. 4. Breast cancer: hard lumps in the breast can also be breast cancer, which is characterized by painless hard lumps in the breast, and once detected, it is necessary to actively accept standardized treatment. 5. Trauma: Trauma to the chest can also lead to hard lumps in the breasts, which can be accelerated by localized hot compresses to promote blood circulation and thus speed up recovery. Breast lumps may also be due to other reasons, it is recommended to go to the hospital in time to clarify the cause of the disease, under the guidance of professional doctors to receive standardized treatment.