A hard lump on the breast may be caused by breast hyperplasia or breast nodules, or it may be due to breast cancer. 1. Mammary gland hyperplasia: Mammary gland hyperplasia is a common disease among women, usually related to the imbalance of the ratio of estrogen and progesterone in the body, and the main symptom is pain in the mammary glands, and there is usually a swelling. 2. Breast nodule: breast nodule is also a common disease among women, most of them are benign nodule, which may be related to hormone level disorder or breast infection, etc. The main symptom is that there will be hard lumps inside the breast, and it is usually painful when touching it with hands, and some patients may have the phenomenon of increased nipple secretion. 3. Breast cancer: There are usually no obvious symptoms in the early stage of breast cancer, but there may be hard lumps when touched by hand. At the same time, hard lumps on the breast can also be seen in breast fibroadenoma, breast cystic hyperplasia, mastitis, breast tuberculosis and other diseases. It is recommended to go to the regular hospital for relevant examinations in time, to clarify what causes, and actively follow the doctor’s advice to adopt the appropriate solutions, so as not to delay the condition.