Cysts are fluid vesicles containing fluid in the breast tissue, similar to blisters. Most cysts develop quickly and then stay the same size. A small number of cysts will shrink or continue to grow. Cysts are usually too small to be felt. However, on ultrasound, the shape of the cyst looks round and clear with distinct contours. Larger cysts can be felt in the breast tissue. Cysts are both soft and hard, and women usually have more than one cyst at a time. Cysts are harmless and non-hazardous, but they can sometimes be uncomfortable or painful. Women often feel that the cyst becomes tender or enlarged a few days before their menstrual period. The cysts may also become more painful when pressure is applied to them. Researchers do not know the cause of cysts. We do know that cysts are common and can affect women of any age. Cysts are especially common in women between the ages of 45 and 50. Cysts often appear during menopause when estrogen changes rapidly and disappear at the end of menopause. Women who are on hormone replacement therapy often have breast cysts. Cysts and cancer Many women are most concerned about whether cysts are cancerous and whether they will become cancerous. Cysts are not cancer. Cysts are not more likely to become cancerous than other parts of the breast. There is no evidence that cysts can cause cancer. It is purely coincidental that cysts and cancer occur in the same area. Diagnosing and treating cysts A physical exam and ultrasound will usually provide enough information for a physician to diagnose the presence of a cyst. If the cyst is large enough to be felt, the physician will usually recommend drainage with a needle. Although the cyst is not dangerous, the drainage will eliminate the mass and will take the worry out of the hands of the majority of women. Cysts that can be seen on ultrasound but are too small to be felt will generally not be drained by physicians. When a cyst is drained, the physician will use a needle to draw out the fluid. This process is called fine needle aspiration cytology (FNA). The FNA may be uncomfortable, but is generally not painful. Women who feel pain say that the pain passes quickly. The fluid in the cyst may be clear or colored (e.g., yellow, green, orange, or black); this fluid is normal and does not need to be sent for examination. The cyst can be drained immediately at the clinic, which takes only two minutes. Your physician will ask you to return in two months for a review. What happens now? The drained cyst will shrink and disappear, and generally no further action is required after that. Many women have cysts that reappear. These may be cysts that have refilled with fluid, or they may be new cysts. The reappearing cysts are not dangerous. Treatment is the same as for the first cyst. If the cyst is drained and the mass fills back up with fluid within 24 hours, then you should make an appointment and see your doctor again. Your cyst does not increase your risk of developing cancer. You should follow the breast cancer screening recommendations specific to your age and family medical history. All women should be alert to abnormal changes in their breasts. If changes in your breasts are different from your normal hormonal changes, they should be checked by a specialist. Feelings For many women, breast pain is distressing. It can cause a lot of feelings and concerns, and the fear of developing cancer is understandable. It is also common to find that the examination gives a sense of pressure and invasiveness. Most of the time women feel relaxed when they learn that breast changes are the result of a common condition that is harmless or not dangerous. Sometimes, however, some women continue to worry about developing cancer. Some women also find that breast changes affect their sense of self, sexuality, or relationships. If breast changes are negatively affecting your life, it can be helpful to share your feelings with a close friend or relative. In addition, you may be able to get information or advice from a specialist. If you feel that talking to a specialist at a mammography clinic will help put your mind at ease, then feel free to talk to him or her.