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:-

shape
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
Round	X
Oval	X
Lobular	X	X
Irregular			X

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
Quite fatty	X
Low	X
Iso	X	X
High			X

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
Well-defined	X
Obscured/75% hidden or more		X
Microlubulated		X
Indistinct and ill-defined		X	X
Spiculated			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.

References

American College of Radiology. Breast Imaging and Reporting Data System. Fifth edition. Reston V A, American College of Radiology 2003.
Gajdos, C., Tartler, PI, Beiweiss, IJ., Hermann, G., de Csepel, J., Eastabrook, A., Rademaker, A., Mammographic Appearance of Nonpalpable Breast Cancer Reflects Pathologic Characteristics. Ann Surg. 2002 February; 235(2): 246–251.
Yokoe T, Maemura M, Takei H, et al. Efficacy of mammography for detecting early breast cancer in women under 50. Anticancer Res 1998; 18: 4709–4712.
Sampat MP, Whitman GJ, Stephens TW, Broemeling LD, Heger NA, Bovik AC, Markey MK. The reliability of measuring physical characteristics of spiculated masses on mammography. Br J Radiol. 2006 Dec;79 Spec No 2:S134-40.
Evans AJ, Wilson ARM, Burrell HC, et al. Mammographic features of ductal carcinoma in situ present on previous mammography. Clin Radiol. 1999;54:644-646.
R. M. Rangayyan, N. M. El-Faramawy, J. E. Desautels, and O. A. Alim. Measures of acutance and shape for classification of breast tumors. IEEE Transactions on Medical Imaging, 16(6):799-810, 1997.
Lamb, P. Correlation Between Ultrasound Characteristics, Mammographic Findings and Histological Grade in Patients with Invasive Ductal Carcinoma of the Breast. Clinical Radiology, Volume 55, Issue 1, Pages 40-44

More References

Evans WP, Warren Burhenne LJ, Laurie L, O’Shaughnessy KF, Castellino RA.Invasive lobular carcinoma of the breast: mammographic characteristics and computer-aided detection. Radiology. 2002 Oct;225(1):182-9.
Cornford EJ, Wilson AR, Athanassiou E, et al. Mammographic features of invasive lobular and invasive ductal carcinoma of the breast: a comparative analysis. Br J Radiol 1995; 68:450-453.
Verheus M, Maskarinec G, Erber E, Steude JS, Killeen J, Hernandez BY, Cline JM.Mammographic density and epithelial histopathologic markers.BMC Cancer. 2009 Jun 13;9:182.
Surendiran, B. Sundaraiah, Y. Vadivel, A. Classifying Digital Mammogram Masses Using Univariate ANOVA Discriminant Analysis. Advances in Recent Technologies in Communication and Computing, 2009.( November 2009)p. 175 – 177
Stein L, Chellman-Jeffers M.The radiologic workup of a palpable breast mass.Cleve Clin J Med. 2009 Mar;76(3):175-80.
Mu, T., Nandi, AK., Rangayyan, RM. Classification of breast masses via transformation of features using kernel principal component analysis. BIEN ’07 Proceedings of the fifth IASTED International Conference: biomedical engineering .(2007)
Eberl MM, Fox CH, Edge SB, Carter CA, Mahoney MC.BI-RADS classification for management of abnormal mammograms.J Am Board Fam Med. 2006 Mar-Apr;19(2):161-4.