There are four possibilities: 1. Cystic hyperplasia of the breast, which is common in women aged 30-50 years old, with clinical manifestations of breast swelling and pain, accompanied by the formation of breast hyperplasia nodules. 2. Breast cancer, which often has no obvious clinical manifestations in the early stage, but when the disease progresses to an advanced stage, it can appear as hidden breast pain, accompanied by general wasting and other manifestations, and a hard, poorly mobile and faintly defined lump can be palpated in the breast. 3. 3.Physiological pain, when women are in puberty and pregnancy, due to the increase of estrogen level, causing breast interstitial congestion and edema, the breast is hidden pain or swelling pain, which does not need special treatment and can be relieved by itself. 4.Mastitis, which usually occurs in lactating women, combined with milk stagnation, the breast only has hidden pain at the beginning of the infection period, and then can gradually appear swelling pain and fluctuating lumps. and fluctuating lumps.