| INTERACTIVE MAMMOGRAPHY ANALYSIS WEB TUTORIAL | TUTORIAL 1 :ANATOMY | POSITIONING | VIEWING THE MAMMOGRAM TUTORIAL 2 :MAMMOGRAM ANALYSIS | NORMAL APPEARANCE | ASYMMETRIC DENSITY | MASSES | CALCIFICATIONS LIST OF CASES |
Tutorial 2 : MASSES (PAGE 2 of 7) | |
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Round, Oval, or Lobulated Lesions with Circumscribed Margins A round, oval, or lobulated mass with sharply defined borders has a high likelihood of being benign. In many cases, a thin, dark line can be seen surrounding the circumscribed lesion. This so-called "halo sign" represent a Mach band reflecting an optical illusion rather than an anatomic sign indicating absence of infiltration of tissue adjacent to a mass. Nonetheless, it must be warned that these characteristics alone will not absolutely rule out the possibility that the lesion may be malignant. Again, case management will depend on other factors such as multiplicity and other associated findings, but the decision whether to follow up or to biopsy is beyond the scope of this tutorial. The typical masses that are round, oval, or lobulated with circumscribed margins are fibroadenomas, cysts, abscess, cystosarcoma phylloides, intramammary lymph nodes, intraductal papillomas,hematomas, and unfortunately, some malignant lesions. A brief description of each is described below. |
| Fibroadenoma A fibroadenoma is a benign tumor common in young women. It develops under the influence of estrogen. Its mammographic appearance is a mass with sharply well-demarcated margin, and it is virtually indistinguishable from a cyst or a well-circumscribed carcinoma. For this reason, it is impossible to identify a fibroadenoma radiographically without additional mammographic features. The additional features that allows one to distinguish a fibroadenoma has to do with the fact that fibroadenomas often regress with menopause. During regression, the noncalcified appearance changes and calcifications develop. The typical involuting fibroadenoma contains "popcorn-like" macrocalcifications and is easily identified on a mammogram. |
| Cysts As noted, a noncalcified fibroadenoma is indistiguishable from a cyst radiographically. That is, cysts generally have clearly defined margins radiographically when not obscured by surrounding tissue parenchyma. Cysts occur as a result of the dilatation of the lactiferous ducts within the lobules due to the imbalance between secretion and resorption. Simple breast cysts are lined by an epithelial layer and contain clear or yellow transudate fluid devoid of calcium. They commonly occur in women between 30 and 50 years of age. Ultrasound and needle aspiration are two common procedures used to diagnose a cyst. |
| Abscess An abscess is a benign lesion which may or may not appear round and well circumscribed. It may be associated with acute mastitis and is often resolved clinically. Lacking a clinical history, only needle aspiration can diagnose an abscess. |
| Cystosarcoma Phylloides (Phylloides Tumor) This lesion has sharp margins, slightly lobulated, and resembles a giant fibroadenoma. Approximately 15% are malignant, and differentiation between a benign and malignant form cannot be made mammographically. |
| Intramammary Lymph Node A normal lymph node is usually small, noncalcified, and has sharp margins. In the oblique mammogram view, they can be found in the axilla. Intramammary lymph nodes, on the other hand, may be interpreted as an occult breast mass. Magnification may be helpful to identify additional mammographic features of a hilus and central fat in which case the likelihood it being benign is increased. |
| Intraductal Papilloma Intraductal papillomas result from a proliferation of ductal epithelial tissue. Often they are too small to be evident on a mammogram. Ocassionally, they may grow large enough to appear as circumscribed masses and in certain instances may even obstruct the duct to give the appearance of duct dilatation. |
| Hematoma Trauma to the breast may cause a hematoma or contusion. A contusion usually does not produce a radiographically visible mass, but a hematoma usually appears as a well-defined, well-circumscribed ovoid mass. With time, a hematoma is expected to resolve completely. However, in certain cases it may leave behind an area of architectural distortion or even a residual mammographic mass density with spiculations. In such a case, if the link with trauma cannot be established, biopsy may be required to determine the suspected area. |
| Circumscribed Breast Cancer By now it should be evident that there are exceptions to the rule that a well-defined circumscribed mass is likely to be benign. Some malignant lesions unfortunately appears well-circumscribed on a mammogram. In many cases, some part of the circumscribed malignant mass is irregular or ill-defined which is indicative of infiltration. |
| Principle of Multiplicity and Bilaterally Influences in the development of one breast should similarly affect the other. Bilateral abnormalities with morphologic features that have a high probability of being benign raise less suspicions than unilateral abnormalities. Likewise, most breast cancers are solitary, and the presence of multiple findings with similar morphological charcteristics are more reassuring. Of course, the rule of multiplicity does not apply when the mammographic features of several masses have a high probability of being malignant. |
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Images reproduced with permission from The MIAS Digital Mammogram Database.