Library · Anatomy
Breast density
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When someone has a mammogram, the radiologist writes the report in a fixed format, and one of its boxes is breast composition: how much glandular tissue and how much fat the breast has. That is breast density, and it has four categories.
They range from an entirely fatty breast to an extremely dense one, with scattered areas of fibroglandular density, meaning glandular and fibrous tissue, and heterogeneously dense in between.
Having dense tissue is common, especially when you are young, because density tends to drop with age.
It matters for one very specific reason: when the tissue is dense, the mammogram is worse at finding a cancer, and it can come back normal when something is there. That is what a false negative means. It is like looking for a white cloud against a clear sky or against a sky that is already overcast.
In brief
Breast density is the part of the mammogram report that describes breast composition, in four categories.
The categories run from entirely fatty through scattered areas of fibroglandular density and heterogeneously dense to extremely dense.
Dense tissue is a common finding, especially in young women, because density usually drops with age.
It matters because mammography detects cancer less well in dense tissue and can give false negatives.
Looking for a white cloud against a clear sky or against a sky that is already overcast.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingMammography BI RADS Grading, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingBreast Cancer Screening in the Average-Risk Patient, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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