extremely dense breast tissue (ek-STREEM-lee dents brest TIH-shoo)
A term used to describe breast tissue that is made up of almost all dense fibrous tissue and glandular tissue. On a mammogram, the dense areas of the breast make it harder to find tumors or other changes. Women who have extremely dense breast tissue have a higher risk of breast cancer than those who have little or no dense breast tissue. Extremely dense breast tissue is one of four categories used to describe a level of breast density seen on a mammogram. About 10% of women have this type of breast tissue.