Breasts are made up of lobules (milk-producing glands) and ducts (tubes that carry milk to the nipple), which are surrounded by glandular, fibrous and fatty tissue. Fibroadenomas develop from a lobule. The glandular tissue and ducts grow over the lobule, forming a lump.
Fibroadenomas are benign (not cancer) and dont increase the risk of developing breast cancer. They are thought to occur because of an increased sensitivity to the female hormone oestrogen.
A fibroadenoma usually has a smooth rubbery texture and can move easily under the skin. Fibroadenomas are usually painless, but some people may feel some tenderness or even pain.
Fibroadenomas are very common and it is not unusual to have more than one. Often developing during puberty, they are mostly found in young women, but can occur at any age.
Most fibroadenomas are about 1 to 3cm in size. When more than 5cm theyre called giant fibroadenomas. Fibroadenomas found in teenage girls are called juvenile fibroadenomas. They may also be giant fibroadenomas.
Most fibroadenomas stay the same size. Some get smaller and some eventually disappear over time. Infrequently, fibroadenomas get bigger, particularly in teenage girls and pregnant and breastfeeding women, but often get smaller again. This is quite normal and nothing to worry about.