Architectural Distortion of

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1 Residents Section Pattern of the Month Gaur et al. rchitectural Distortion of the reast Residents Section Pattern of the Month Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Shantanu Gaur 1 Vandana Dialani 1,2 Priscilla J. Slanetz 1,2 Ronald L. Eisenberg 1,2 Gaur S, Dialani V, Slanetz PJ, Eisenberg RL Keywords: architectural distortion, breast DOI: /JR Received October 10, 2012; accepted after revision January 24, Harvard Medical School, oston, M. 2 Department of Radiology, eth Israel Deaconess Medical enter, 330 rookline ve, oston, M, ddress correspondence to V. Dialani (vdialani@bidmc.harvard.edu). WE This is a web exclusive article. JR 2013; 201:W662 W X/13/2015 W662 merican Roentgen Ray Society rchitectural Distortion of the reast rchitectural distortion is the third most common mammographic appearance of nonpalpable breast cancer, representing nearly 6% of abnormalities detected on screening mammography. lthough its prevalence on mammography is small compared with calcification or visible mass, architectural distortion is also more difficult to diagnose because it can be subtle and variable in presentation. Indeed, architectural distortion is a common finding in retrospective assessments of false-negative mammography and may represent the earliest manifestation of breast cancer. Moreover, some studies suggest that early detection of architectural distortion may be associated with a more significant improvement in prognosis than earlier detection of calcifications. Several automated approaches have been developed to increase the detection rate of architectural distortion, but they remain imperfect (detection rate of less than one half with one method). This article discusses the benign and malignant causes of architectural distortion and illustrates its various manifestations in an effort to reduce undiagnosed architectural distortion on screening mammography. Manifestations of rchitectural Distortion rchitectural distortion is defined by the reast Imaging Reporting and Data System (I-RDS) system as an appearance in which the normal architecture of the breast is distorted with no definite mass visible. This includes spiculations radiating from a point and focal retraction or distortion at the edge of the parenchyma. rchitectural distortion can also be an associated finding. enign causes of architectural distortion include radial scars; complex sclerosing lesions; sclerosing adenosis; fat necrosis; postprocedural change; and rare spiculated benign lesions, such as granular cell tumor and breast fibromatosis. Malignant causes include breast cancer and ductal carcinoma in situ (DIS) (Table 1). enign auses of rchitectural Distortion Radial Scars and omplex Sclerosing Lesions oth radial scars and complex sclerosing lesions result from idiopathic processes unrelated to trauma or postsurgical change. They are characterized microscopically by radiating ducts and lobules that show varying degrees of hyperplasia, adenosis, ectasia, or papillomatosis. omplex sclerosing lesions are usually larger than 1 cm and display more proliferative tissue than radial scars. ecause most patients are asymptomatic and the lesions are not palpable, radial scars and complex sclerosing lesions are usually discovered as incidental findings on screening mammography. However, they pose a diagnostic challenge because they closely mimic scirrhous carcinomas. The typical mammographic appearance is a radiolucent central core with spiculated radiations, at times associated with microcalcifications (Fig. 1). On ultrasound, radial scars commonly present as a hypoechoic mass or parenchymal distortion that mimics malignancy. On MRI, the morphologic features and contrast enhancement patterns of radial scars and complex sclerosing lesions cannot reliably differentiate a benign from malignant process. There is only limited evidence supporting the rate of enhancement as a useful differentiating factor. ecause of the inability to reliably differentiate radial scars and complex sclerosing lesions from carcinoma, the lesion must be biopsied and excised. Sclerosing denosis Sclerosing adenosis is recognized microscopically by an increase in the number of W662 JR:201, November 2013

2 rchitectural Distortion of the reast TLE 1: Differential Diagnosis for rchitectural Distortion Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Diagnosis auses Imaging Findings enign Radial scars and complex sclerosing lesions Focal architectural distortion, radiolucent central core, spiculated Sclerosing adenosis Microcalcifications, mass, focal architectural distortion Fat necrosis Spiculated lesions with skin thickening and retractions Postprocedural change Parenchymal scar with focal architectural distortion, swirling pattern after mammoplasty Rare spiculated benign lesions (granular cell tumor Spiculated masses without calcification and breast fibromatosis) Malignant ancer Radiating spicules from a central mass Ductal carcinoma in situ Microcalcifications with focal architectural distortion glands within the lobular units. The associated proliferation of acinar, myoepithelial, and connective tissue elements leads to architectural distortion on imaging. lthough a benign process, sclerosing adenosis remains an important radiographic finding because it can coexist with both invasive and in situ cancers, is frequently not palpable and asymptomatic on clinical presentation, and is usually discovered incidentally on mammography. Sclerosing adenosis may present with microcalcifications, mass, or focal architectural distortion on mammography. There are no typical ultrasound findings, although limited evidence suggests that a circumscribed, hypoechoic, or isoechoic mass is typical of the nodular variant, which is characterized by confluent areas of sclerosing adenosis. Fat Necrosis Fat necrosis is a benign inflammatory process within the fatty tissue of the breast that may mimic malignancy clinically, mammographically, and sonographically. The most common causes of fat necrosis are surgery (biopsy, lumpectomy, reduction mammoplasty, implant removal, and breast reconstruction) and radiation therapy. nother important cause is trauma, including blunt chest trauma or seat belt injury or even minor trauma that the patient may not recollect. Rarely, anticoagulant therapy can be a cause. Fat necrosis is usually asymptomatic and discovered on routine mammography. On mammography, the most typical appearances consist of either oval radiolucent oil cysts with thin capsules or thickening and deformity of the skin and subcutaneous tissue. oth of these appearances can be associated with dystrophic calcification. However, when fibrosis predominates in the inflammatory response, fat necrosis can appear as a spiculated ill-defined mass with gross skin thickening and retraction, closely mimicking breast cancer (Fig. 2). On ultrasound, fat necrosis can be cystic or solid with mixed internal echotexture. rchitectural distortion is one of the broad spectrums of many MRI findings in fat necrosis. When spiculated or distorted, fat necrosis can be differentiated from malignancy on MRI because it typically follows the signal intensity of fat on all sequences Postprocedural hange rchitectural distortion is a common finding in the breast within the first 6 months after biopsy (Fig. 3). The distortion arises from the scarring process after surgery and can rarely be evident grossly as a lump or thickening of the skin around the incision site. On mammography, postbiopsy features in addition to architectural distortion include skin changes, glandular tissue defect, parenchymal scar, calcification, opaque foreign body, and fat necrosis. rchitectural distortion is present on up to 80% of mammograms at 6 months after excisional biopsy, decreasing to 35% at 2 years. Ultrasound rarely shows frank distortion after benign breast biopsy but can reveal an irregular hypoechoic mass with posterior shadowing. Postlumpectomy rchitectural distortion associated with postlumpectomy change can remain a permanent feature after surgery (Fig. 4). However, as in postbiopsy change, any increase in size of the distorted area is suspicious for recurrence. Ultrasound is less useful than MRI in evaluating the postsurgical bed. ny enhancement in the surgical bed on MRI that persists for 18 months or more after surgery is concerning for recurrence. Reduction Mammoplasty rchitectural distortion is readily apparent in women undergoing reduction mammoplasty. The most common radiographic change is skin thickening and retraction of the lower portion of the breast. The distorted area is often characterized by a swirling pattern of architectural distortion associated with the mammoplasty scars (Fig. 5). Scarring can also lead to the detection of architectural distortion on ultrasound, but this modality is more valuable in the immediate postoperative state to detect seroma, hematoma, or abscess. Rare Spiculated enign Lesions Rarer benign causes of architectural distortion that appear as spiculated lesions include fibromatosis (extra abdominal desmoid tumor) and granular cell tumor. Fibromatosis is microscopically characterized as an infiltrating mass composed of fibroblasts and collagen that is frequently found in the abdominal wall. It rarely occurs in the breast, where the lesion may present as a mobile, firm, and painless mass. On mammography, the lesion appears as a speculated irregular or ill-defined dense mass without associated calcifications that is indistinguishable from malignancy. Similarly, the appearance of fibromatosis on ultrasound resembles malignancy, appearing as an irregular hypoechoic mass with posterior acoustic shadowing. In one report, breast fibromatosis showed an isointense mass on unenhanced T1- weighted images, heterogeneously, low- to high-intensity mass on fat-suppressed T2- weighted images, and heterogeneous gradual enhancement on dynamic MRI, similar to the appearance of musculoskeletal fibromatosis (Fig. 6). Granular cell tumors usually present as painless mobile masses in the upper quadrants of the breast, usually the upper inner quadrant because they originate within the primitive nerve cells. On mammography, the mass may have various appearances, ranging from an ill-defined and spiculated mass with architectural distortion to a round and wellcircumscribed mass, usually without microcalcifications. The ultrasound appearance is similarly varied, manifesting as poorly circumscribed or well-circumscribed with posterior shadowing (Fig. 7). JR:201, November 2013 W663

3 Gaur et al. Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Malignant auses of rchitectural Distortion reast ancer The two most common types of invasive breast cancers that can produce architectural distortion on mammography are invasive ductal carcinoma (ID) and invasive lobular carcinoma (IL), which represent about 70 90% and 5 10% of invasive breast malignancies, respectively. lthough an irregular mass or calcification is the most common mammographic appearance of invasive cancer, architectural distortion is generally considered the third most frequent and sometimes the only presenting finding (Fig. 8). In one retrospective study of pure IL, a spiculated mass or architectural distortion was the most common radiographic finding. linically, the patient can be entirely asymptomatic but present with palpable lumps or anatomic distortion of the breast on physical examination. On mammography, the architectural distortion associated with either ID or IL may appear as spicules radiating from a central mass. In response to local infiltration into the surrounding tissue, the architectural distortion may have a star-shaped pattern. There may be no ultrasound correlate to the architectural distortion in the absence of a palpable or mammographically apparent mass. In the presence of a correlate, ultrasound can provide guidance for biopsy (Fig. 8). The presence of an enhancing mass with plateau or washout kinetics can be seen on MRI evaluation and may also provide guidance for biopsy. Ductal arcinoma in Situ DIS is a noninvasive premalignant condition characterized by ductal cell proliferation with no histologic evidence of invasion through the basement membrane. On mammography, DIS most commonly presents typically with pleomorphic, linear, or linear branching microcalcifications, but architectural distortion has been described as occurring in up to 2 10% of patients (Fig. 9). lthough the most common features of DIS on ultrasound are hypoechoic masses and microcalcifications, architectural distortion may be seen in up to 4% of cases, MRI typically shows clumped linear or ductal nonmasslike enhancement (Fig. 9). In conclusion, architectural distortion represents the third most common imaging appearance of malignancy. iopsy is often necessary to exclude malignancy unless it is possible to identify an obvious benign cause, such as postsurgical or postprocedural change or fat necrosis. Suggested Reading 1. lleva DQ, Smetherman DH, Farr GH, ederbom GJ. Radial scar of the breast: radiologic-pathologic correlation in 22 cases. RadioGraphics 1999; 19(spec no):s27 S35 2. aker J, Rosen EL, Lo JY, Gimenez EI, Welsh R, Soo MS. omputer-aided detection (D) in screening mammography: sensitivity of commercial D systems for detecting architectural distortion. JR 2003; 181: roeders MJ, Onland-Moret N, Rijken HJ, Hendriks JH, Verbeek L, Holland R. Use of previous screening mammograms to identify features indicating cases that would have a possible gain in prognosis following earlier detection. Eur J ancer 2003; 39: D Orsi, Mendelson E, Ikeda D, et al. reast Imaging Reporting and Data System: R I- RDS breast imaging atlas. Reston, V: merican ollege of Radiology, DiPiro PJ, Gulizia J, Lester S, Meyer JE. Mammographic and sonographic appearances of nodular adenosis. JR 2000; 175: Feder JM, de Paredes ES, Hogge JP, Wilken JJ. Unusual breast lesions: radiologic-pathologic correlation. RadioGraphics 1999; 19(spec no):s11 S26 7. Gill HK, Ioffe O, erg W. When is a diagnosis of sclerosing adenosis acceptable at core biopsy? Radiology 2003; 228: Hogge JP, Robinson RE, Magnant M, Zuurbier R. The mammographic spectrum of fat necrosis of the breast. RadioGraphics 1995; 15: Miller L, Feig S, Fox JW. Mammographic changes after reduction mammoplasty. JR 1987; 149: Nakazono T, Satoh T, Hamamoto T, Kudo S. Dynamic MRI of fibromatosis of the breast. JR 2003; 181: Sekine K, Tsunoda-Shimizu H, Kikuchi M, Saida Y, Kawasaki T, Suzuki K. DIS showing architectural distortion on the screening mammogram: comparison of mammographic and pathological findings. reast ancer 2007; 14: Sickles E, Herzog K. Mammography of the postsurgical breast. JR 1981; 136: (Figures start on next page) W664 JR:201, November 2013

4 rchitectural Distortion of the reast Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 1 Radial scar and complex sclerosing lesion. and, Mediolateral oblique () and craniocaudal () screening mammograms in 48-year-old woman show area of architectural distortion in left breast (arrows). Histology showed radial scar., Fat-saturated contrast-enhanced MR image in 49-year-old woman shows large area of architectural distortion involving left breast. Histology showed complex sclerosing lesion. Fig. 2 Fat necrosis in 79-year-old woman who presented for screening mammography. Patient had no history of trauma or breast surgery. and, Mediolateral oblique () and craniocaudal () mammograms show large area of architectural distortion (arrows) with microcalcifications. ircle () indicates skin lesion. (Fig. 2 continues on next page) JR:201, November 2013 W665

5 Gaur et al. Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 2 (continued) Fat necrosis in 79-year-old woman who presented for screening mammography. Patient had no history of trauma or breast surgery., Ultrasound image shows irregular hypoechoic mass with posterior shadowing (arrows). Ultrasound-guided core biopsy was performed and histology showed fat necrosis. D, Magnified mediolateral image of lumpectomy bed shows classic fat necrosis, which is seen as calcified oil cysts on mammography. Fig. 3 rchitectural distortion after benign breast biopsy in 62-year-old woman with history of excisional biopsy. and, Mediolateral oblique () and craniocaudal () screening mammograms show atypical lobular hyperplasia in left upper central breast with architectural distortion (arrows) at site of previous biopsy. D W666 JR:201, November 2013

6 rchitectural Distortion of the reast Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved D Fig. 4 rchitectural distortion after partial mastectomy in 70-year-old woman who had undergone partial mastectomy 4 years previously. and, raniocaudal () and mediolateral oblique () images from routine annual mammography show area of architectural distortion (arrows) with skin defect at previous surgical site (marked with overlying scar marker and surgical clips noted in surgical bed). ircles ( and ) indicate skin lesions. and D, raniocaudal () and mediolateral oblique (D) images obtained before partial mastectomy show irregular mass that was biopsy-proven cancer (arrows) and was excised. Fig. 5 rchitectural distortion after reduction mammoplasty in 52-year-old woman who underwent bilateral reduction mammoplasty 4 years ago. and, Mediolateral oblique mammograms show architectural distortion producing characteristic swirling pattern (arrows). JR:201, November 2013 W667

7 Gaur et al. Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Fig year-old woman with fibromatosis of left breast. (Reprinted with permission from Nakazono T, Satoh T, Hamamoto T, Kudo S. Dynamic MRI of fibromatosis of the breast. JR 2003; 181: ), Mammogram shows spiculated mass with architectural distortion (arrows) in upper left breast., xial fat-suppressed T2-weighted image reveals mass with areas of low intensity (arrowhead) to high intensity (arrows) relative to normal surrounding tissue of mammary gland., ontrast-enhanced axial fat-suppressed T1-weighted image shows ill-defined mass (arrows) with heterogeneous enhancement. D, Dynamic MR image reveals gradual enhancement of mass. D W668 JR:201, November 2013

8 rchitectural Distortion of the reast Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 7 Granular cell tumor in 46-year-old woman. and, Mediolateral oblique () and craniocaudal () screening mammograms show subtle area of architectural distortion (arrows)., Ultrasound image shows well-circumscribed mass with posterior shadowing. Ultrasound-guided core biopsy was performed, and histology showed granular cell tumor. Fig. 8 Intraductal carcinoma in 62-year-old woman who presented with palpable mass (marked with )., Mediolateral oblique () and craniocaudal () and magnification craniocaudal () images show large area of architectural distortion (arrows) with pleomorphic microcalcifications (arrowheads, and ). alcifications are better appreciated on magnification image (). (Fig. 8 continues on next page) JR:201, November 2013 W669

9 Gaur et al. Fig. 8 (continued) Intraductal carcinoma in 62-year-old woman who presented with palpable mass (marked with ). D, Ultrasound image shows irregular hypoechoic mass with posterior shadowing (arrows). Ultrasound guided-core biopsy was performed, and histology showed invasive ductal carcinoma. Downloaded from by on 01/05/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 9 Ductal carcinoma in situ (DIS) in 72-year-old woman who had history of surgical excision (marked with scar marker) anterior to area of architectural distortion (arrows)., Mediolateral oblique () and craniocaudal () mammograms and contrastenhanced subtraction MR () images show linear area of clumped enhancement characteristic of DIS. MRI-guided core biopsy was performed, and histology showed DIS. D W670 JR:201, November 2013