Most woman will have cysts in the breast at some time during her life. They are usually very small and most women are not aware of cysts until they have an ultrasound scan. Breast cysts primarily develop as the result of hormonal changes in the breast and are uncommon after the menopause except in women who take HRT.

A breast cyst consists of a very thin lining of cells which originally derive from a small breast duct, and contains fluid with oestrogen. Cysts can develop very quickly over a matter of days and this can lead to a lump that appears to have arisen almost overnight, which can be quite tender. Most breast cysts eventually disappear by themselves though this may take many months. The size of cysts vary from a small pinhead to golf ball size.

Breast cysts are best diagnosed by an ultrasound scan. It is very unusual indeed to develop any serious consequences from breast cysts. They are nearly always entirely harmless and this is very effectively demonstrated by the ultrasound.

In very rare cases, breast cysts develop pre-cancerous changes. When one considers that nearly every woman will have breast cysts at some time in her life you should not consider breast cysts as having any significant malignant potential. Most Consultants will advise that breast cysts are left alone. If the cyst is large and uncomfortable a needle can be inserted in the cyst and the fluid contents withdrawn. The cyst will then disappear and it is uncommon for it to refill.