Most breast masses appear in the second part of the menstrual period and disappear by shrinking with menstruation. These masses are most likely what we call breast cysts. However, when any mass is detected in the breast, it should be investigated because of the possibility of breast cancer. Most of the cysts do not require treatment. If it is a simple cyst, there is no need for follow-up. If the cyst is complicated or with dense content, it is followed by ultrasound at an average of 6 months. If the fluid in the cyst is irregular, granular or bloody, the fluid is drained with an injector and this fluid is examined in pathology. If necessary, the cyst should be surgically removed and examined.