Fibroadenoma is a very common benign (noncancerous) breast condition that often develops during puberty but can occur in women of any age. Its causes are unknown but it is thought that it probably occurs because of increased sensitivity to the hormone oestrogen. Most fibroadenomas stay the same size. Some get smaller and some eventually disappear over time. However, it is important to get screened if you notice any lump in your breast.