7% of women in Singapore will develop breast cysts at some point in their lives. Breast cysts are caused when you have excess of the hormone estrogen and insufficient progesterone. This stimulates connective tissue to grow.
A breast cyst is simply a small sac of connective tissue filled with fluid. They manifest as lump or nodule, often with swelling and pain, although some women do not experience any symptoms. The pain is usually "cyclical", meaning it gets worse just before menstruation. The condition tends to get worse with age, reaching a peak when you are in your 40's. After menopause, your estrogen levels drop drastically, and the cysts will naturally shrink to nothing.
They are mostly harmless and easily treated, but it is essential to see your doctor if you detect any type of lump in your breast. A test may be required to ensure that the lump is not a form of breast cancer.