Mass = 3D area that is either more or less dense than the surrounding breast tissue; "Silhouette sign"

Must have 3 features to be called a mass

–     Shape

–     Margins

–     Density

Describing a mass

–     Size: Maximum diameter

–     Shape: Round/ovoid, lobular, irregular

–     Margins: Circumscribed, macrolobulated, microlobulated, obscured (< 75% margin is visualized), indistinct, spiculated

–     Density: Low, equal, high (compared to nearby fibroglandular tissue)

–     Location: To quadrant or clock-face location with distance from nipple