“Usual hyperplasia” means there is excessive growth of benign cells in an area of the breast, but the cells don’t look abnormal. This can happen along the inner lining of the breast duct (tube that carries milk to the nipple) or the lobule (small round sac that produces milk).
The cells closely resemble normal cells, although their nuclei (cell centers that contain genetic material) can vary in size, shape, and placement. In some cases, the cells can fill the entire duct or lobule and even cause it to swell outward. There is a slight increase in breast cancer risk associated with this condition; however, the vast majority of women will never have a problem.
In some cases, the hyperplasia cells can look exactly like normal, healthy breast cells. For these women, there is likely no increase in breast cancer risk.