Breast cysts are fluid-filled sacs that develop in the breast.
(See also Overview of Breast Disorders and Breast Lumps.)
Breast cysts are common. In some women, cysts develop frequently, sometimes with other changes in fibroglandular tissue (composed of fibrous connective tissue and glands) in the breast. Cysts when accompanied by these changes (including pain and general lumpiness) are called fibrocystic changes.
The cause of breast cysts is unknown, although injury may be involved.
Breast cysts can be tiny or several inches in diameter.
Cysts sometimes cause breast pain. To relieve the pain, a doctor may drain fluid from the cyst with a thin needle (called aspiration). The fluid is examined under a microscope to check for cancer only if any of the following occurs:
The fluid is bloody or cloudy.
Little fluid is obtained.
The lump is still present after the fluid is drained.
Otherwise, a woman is checked again in 4 to 8 weeks. If the cyst can no longer be felt at this time, it is considered noncancerous. If it has reappeared, it is drained again, and the fluid is examined under a microscope. If the cyst reappears a third time or if it is still present after it was drained, a biopsy is done.
Rarely, when breast cancer is suspected, cysts are removed.
