The Breast Mass on Mammogram
When a radiologist interprets a mammogram, there are a number of characteristic abnormalities in breast tissue which they will be looking for. Sometimes they will note simple changes in density, a ‘distortion‘, or the presence of microcalcifications.
However, at others times, the breast X-ray will clearly reveal a mass, which may not be clinically palpable. Most breast masses occur due to benign causes, but certain characteristics of a breast mass may be more suspicious for breast cancer.
This page is getting a little old, but still has some great information. We do have a new up-to-date page with even more information on Mammographic mass characteritics.
When is a breast ‘lesion’ called a ‘mass’?
A mass is usually something a little more substantial and clear than a ‘lesion‘ per se. A breast mass has volume and it occupies space. It may be in any shape but usually has convex outside borders. A breast mass tends to be denser in the middle than towards the edges.
The tissues within a breast mass do not contain fat cells to the same degree as normal tissue. A mass that specialists discover on during a mammogram will typically be described according to the:-
- density (the amount of fat cells present and density of suspicious cells)
- margin (characteristics of it’s ‘edge‘).
Summary of typical Breast Mass characteristics
|Shape||Likely Benign||Suspicious||Highly Suspicious of Malignancy|
If the mass appears more like a ‘lobule‘ than a purely round or oval shape, then it is somewhat more suspicious for breast cancer. A breast mass appearing with a very irregular or ‘random‘ shape is highly suspicious for breast cancer.
Breast Mass Density and Cancer
|Density||Likely Benign||Suspicious||Highly Suspicious of Malignancy|
The ‘density‘ of a mass, in terms of the relative amounts of fatty elements present, becomes highly suspicious for breast cancer when the density is high. In other words, when there is little evidence on mammogram of fatty tissue within the mass, this tends to suggest that the mass may be primarily malignant cancer cells.
The Margins of the Breast Mass are important
|Margin||Likely Benign||Suspicious||Highly Suspicious of Malignancy|
|Obscured/75% hidden or more||X|
|Indistinct and ill-defined||X||X|
A radiologist interpreting a breast cancer screening mammogram will be alarmed when they discover a mass with a poorly defined or spiculated margin.
Another worrying sign is if the margin seems ‘blurry‘. This might indicate that breast cancer cells are infiltrating into the surrounding tissue. Most benign breast lesions and tumors have well-defined borders, but not all.
A mass with an ill-defined margin will certainly need further testing, usually by ultrasound. Ultrasound is quite good for determining the nature of mass borders. If there is still cause for concern a biopsy may be necessary.
Remember that a breast mass is but one of many diagnostic characteristics of breast cancer. Other techniques and attributes are then used to predict the potential malignancy of the lesion and the extent to which it may have spread.
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