These mammographic findings are then further characterized and compared to old studies, if available. Mammographicaly a mass is defined as a space occupying lesion seen in two different projections, with density defined as a collection seen in only one view. A mass is then further characterized by it's shape, margins, density, size, orientation and presence of associated calcifications. Shape is a generally nonspecific characteristic, both benign and malignant masses tend to develop in one spot and grow circumferentially. An irregular shape is more concerning as its suggests indistinct or irregular margins.
Some intramammary nodes have a typical reniform configuration with a fatty notch.
Margin or contour analysis characterizes the transition zone from mass to surrounding parenchyma or fatty tissue. The significance arises from the tendency of invasive carcinoma to infiltrate adjacent tissue and have indistinct, microlobulated or frankly spiculated margins. Well circumscribed or sharply marginated masses , either with or without a radiolucent halo, are probably benign. When initially found ultrasound to exclude a cyst is a very useful adjuvant study. An alternative to serial imaging would be FNA or core needle biopsy.