Breast cysts are one of the most common disorders seen in mammography clinics. About 7-10% of women of childbearing age have cysts in their breasts, with a peak incidence between the ages of 40 and 50, and a rapid decline in incidence after menopause. The normal degeneration of the epithelial tissue in the lobules of the breast depends on the persistence of the specific mesenchyme around them. If the mesenchyme of the nipple disappears too early and the epithelial vesicles remain, tiny cysts may form, or if the ducts of the breast are blocked, they may develop into large cysts. The etiological factors specific to the formation of such derangements, breast cysts, are not clear, and some indirect evidence confirms that high estrogen expression is a direct or related cause of the disease, such as the application of estrogenic drugs to improve menopausal symptoms in women older than 50 years is one of the causes of cyst formation. The usual diet should pay attention to reduce the intake of high-protein and high-estrogen foods and drugs, such as seafood, Xueha, royal jelly, pollen, birth control pills and sheep placenta. Patients often find lumps when they touch their breasts unintentionally or with breast pain. The lumps feel smooth, movable and cystic on the surface, however, if the pressure inside the capsule is high, they will feel harder and resemble solid tumors. Some patients may notice a large cyst in the breast only when they have sudden pain due to a sudden increase in intracapsular pressure or chemical inflammation caused by extravasation of cystic fluid. Echo-free areas are round or ovoid with clear borders, thin and smooth walls, good sound transmission, and sometimes separated bands of light with enhanced or no posterior echogenicity. When cystic fluid extravasation causes inflammatory reaction in surrounding tissues, the ultrasound image of the cyst becomes atypical. Breast cysts should be differentiated from solid occupying lesions. Most cysts are currently treated with ultrasound-guided or direct cyst aspiration and more often with close follow-up. If the intracapsular fluid of a breast cyst is bloody to the naked eye after aspiration, cytological examination of the cystic fluid is required. If it is non-bloody, cytological examination of the cystic fluid is chosen in conjunction with the physician’s clinical considerations or the patient’s wishes, and if the cytological findings suggest cellular anomalies, suspected malignancy or malignancy, excisional biopsy of the mass is subsequently required. If ultrasonography reveals the presence of a solid occupancy within the cyst, ultrasound-guided core puncture biopsy of the solid area is required along with cyst fluid cytology. More women with breast cysts opt for close follow-up, which includes a clinical examination by a specialist and a breast ultrasound, plus a high-frequency mammogram in women over 35 years of age, mainly to rule out incidental breast cancer. Although cysts are a nuisance, they hardly cause any associated lesions and it is important to clarify that although they have the potential to increase the risk of a little breast cancer, they are not precancerous per se, so surgical removal is basically unnecessary.