A 40 year old female with no symptoms presents for her first screening mammogram and a lobular, circumscribed, partially obscured, isodense mass is found. This was biopsied and found to be a fibroadenoma.
The term "mass" should be used with a space occupying lesion is seen in two different projections. If it is only seen in a single projection is should be called an "asymmetry."
In addition to measurements, descriptors of masses that should be mentioned include shape, margins and density. Each of these categories includes specific terms defined in the BI-RADS lexicon.
Shapes include round, oval, lobular, and irregular.
Margins of a mass may be circumscribed, microlobulated, obscured, indistinct, or spiculated.
In this case the term circumscribed was used because more than 75% of the margins are sharply demarcated. The term partially obscured was used because a small portion of the margins were initially obscured by overlying normal parenchymal tissue. Circumscribed margins were confirmed on follow-up spot compression views.
The density of masses is compared to fibroglandular breast tissue. Descriptors of density include high density, equal density (isodense), low density, and fat-containing radiolucent.