A hard lump in the breast is often a sign of breast disease. The most common breast diseases we see are breast hyperplasia, benign breast tumors and breast cancer. The lumps that occur in breast hyperplasia are often tough and have a significant correlation with the menstrual cycle. For example, before menstruation, the lump may become harder, larger, or more painful, and after menstruation is over, the lump may become softer, smaller, or less painful. In addition, the boundary between the lump and the surrounding glands is not particularly clear, but it can be pushed to have a clear sense of movement, and there is obvious pressure pain, which is a common feature of the lump in breast hyperplasia. Another kind of benign breast tumors, such as common breast fibroma, breast adenoma, they also have obvious hard lumps. The hard lumps of benign tumors are usually very well demarcated from the surrounding area, have no obvious pain, have a noticeable sense of movement, and in addition grow more slowly. The most terrible is the hard lump formed by breast cancer. The hard lump of breast cancer is often very hard, and usually the pain is not particularly obvious, when this lump invades the pleura or other tissues such as the pectoralis major muscle, a painful sensation may appear. The boundaries between this hard lump and the surrounding tissue are not particularly clear, and in severe cases there is no way to push the lump. In some people, the skin on the surface of the lump may sink downward, showing a dimple-like appearance, which we call the dimple sign. Some people may have pitting of the skin, like the surface of an orange peel, which we call the orange peel sign. If such a lump appears, then you must be especially vigilant, please go to the hospital.