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Breast Imaging

E2964. A Wolf in Sheep’s Clothing: Aggressive Cancers That Mimic Benign Disease: How to Tell Them Apart

Hogan M,  Conant E,  Weinstein S,  Chong A,  McDonald E. University of Pennsylvania, Philadelphia, PA

Address correspondence to M. Hogan (parsons.molly@gmail.com)

Background Information: Triple negative breast cancers (TNBCs) are a unique subset of breast cancers that lack estrogen receptors, progesterone receptors and human epidermal growth factor-2 receptors. This histologic subtype often portends a worse prognosis for the patient owing to a multitude of factors including baseline aggressive tumor biology and limited treatment options. As such, accurate and timely tissue diagnosis is of utmost importance in this patient population. TNBCs may share imaging characteristics with more benign fibroepithelial lesions, the most common benign solid breast mass to occur in women of all ages. As a result, some women undergo unnecessary biopsy of these benign masses in order to exclude one of the more ominous possibilities of a TNBC. A comprehensive understanding of the imaging features of TNBCs and fibroepithelial lesions is critical for every radiologist interpreting breast imaging examinations in order to ensure both timely diagnosis of TNBCs and avoid overimaging and biopsy of benign breast masses.

Educational Goals/Teaching Points: The goals of this exhibit are to review the epidemiology of TNBCs and benign breast masses, notably, fibroepithelial lesions, enumerate the mammographic, sonographic and MRI features of benign solid breast masses and breast cancers that share benign features, provide a pictorial, case-based review of the imaging characteristics of fibroadenomas versus triple negative breast cancers, and discuss relevant management decisions of masses with benign imaging features.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: The key sonographic findings that support a benign etiology include an oval shape, circumscribed margins, hypoechoic echotexture, often with internal parallel bright echoes and similar vascularity compared to surrounding fibroglandular tissue. Sonographic features that would sway the reader towards biopsy would include round or irregular shape, indistinct or microlobulated margins, markedly hypoechoic echotexture, and hypervascularity. Many mammographic features of benign disease are the same as those seen sonographically with the additional visualization of coarse or “popcornlike” calcifications on mammogram, although calcifications can often also be seen sonographically, and relatively low to equal radiodensity. TNBCs commonly do not demonstrates associated calcifications and tend to be high radiodensity on mammograms. MRI features supporting the benignity of a lesion include an oval shape, homogeneous enhancement with or without dark nonenhancing septations, and intrinsic T2 hyperintensity. Findings that raise suspicion include round or irregular shape, spiculated or irregular margins and heterogeneous enhancement.

Conclusion: All radiologists interpreting breast imaging examinations should be well-versed in the imaging features of benign breast masses and be able to differentiate these from the more ominous TNBCs. Both sonographic and mammographic imaging can help determine the need for tissue sampling versus benign categorization of breast masses.