The condition in which cystic developments in the breast are frequently observed, which was defined as fibrocystic disease for years, is no longer considered a disease and is called fibrocystic structure. Fibrocystic structure is now accepted as a form of normal and is an innate condition. In other words, it is a genetically determined characteristic of yours, such as whether your eye color is blue or brown or whether you are blonde or brunette. It is seen in approximately 40-50% of women.

Fibrocystic structure brings with it a number of features; increased fibrosis, cystic developments and prominence in the milk ducts can be seen at various rates. Fibrocystic structure alone is not a risk factor for breast cancer.