Cystic hyperplasia of the breast is a disease caused by endocrine dysfunction in women that results in hyperplasia and incomplete regeneration of the mammary epithelium and mesenchyme. Due to the long-term effect of sex hormone imbalance, both hyperplasia and regenerative changes may coexist, and the histological changes may be different at different times of the disease, and the clinical manifestations may also vary. Therefore, there are many names for this disease, such as cystic hyperplasia, mammary adenopathy, mammary fibroadenopathy, mammary hyperplasia, and lobular hyperplasia, but in fact, the names are just different periods of the disease. Clinical manifestations: It occurs mostly in women of childbearing age, with a higher incidence in women aged 30 to 40. The initial lesion can be in one breast, and more than half of them are bilateral. The main manifestations are breast pain, pressure pain, limited glandular thickening or mass formation. (a) Breast pain Mostly swelling or pins-and-needles pain, which may radiate to the axilla and upper limbs of the affected side in severe cases. At the same time, the sensitivity of the breast increases, and the pain can be aggravated by touch and pressure. The regularity of pain disappears in the later stages of the disease. (b) Breast masses may be limited to one or both sides, often multiple. It may be accompanied by the relief of breast pain during menstruation and the reduction or disappearance of breast masses. In the progressive stage, thickened glands with indistinct borders can be found in the breast, and some of them appear as lumpy or cystic masses, and patients often visit the clinic because they think they have breast lumps. (iii) Nipple overflow A small number of patients with cystic hyperplasia have nipple overflow, mostly from multiple breast ducts bilaterally, which can be watery, yellow plasma-like, milk-like or turbid. Most patients are very concerned about the relationship between cystic hyperplasia and the development of breast cancer. In recent years, most scholars disagree that cystic hyperplasia of breast is a precancerous lesion and believe that the incidence of cystic hyperplasia of breast is high but the cancer rate is low. Therefore, generalizing cystic breast hyperplasia as precancerous lesions may cause misunderstanding and increase the pressure of society, patients and doctors.