(Radiographics. 1999;19:S39-S51.)
© RSNA, 1999
Imaging Spectrum of Extracapsular Silicone: Correlation of US, MR Imaging, Mammographic, and Histopathologic Findings1
Cynthia I. Caskey, MD,
Wendie A. Berg, MD, PhD,
Ulrike M. Hamper, MD,
Sheila Sheth, MD,
Bernard W. Chang, MD and
Norman D. Anderson, MD
1 From the Russell H. Morgan Department of Radiology and Radiological Sciences (C.I.C., W.A.B., U.M.H., S.S.), Department of Plastic and Reconstructive Surgery (B.W.C.), and Department of Internal Medicine (N.D.A.), Johns Hopkins University School of Medicine, Baltimore, Md; and the Department of Radiology, University of Maryland School of Medicine, Baltimore (W.A.B.). Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received February 15, 1999; revision requested April 5 and received April 26; accepted April 28. Address reprint requests to C.I.C., Department of Radiology, University of Texas, Lyndon B. Johnson General Hospital, 5656 Kelley St, Houston, TX 77026.
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Abstract
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The appearance of free silicone at mammography, ultrasonography (US), and magnetic resonance (MR) imaging is variable. The classic appearance is dense areas of opacity on mammograms, a highly echogenic pattern with or without hypoechoic masses on US images, and foci of low signal intensity on fat-suppressed T1-weighted MR images or high signal intensity on water-suppressed T2-weighted MR images. Mammography is a reliable, cost-effective, and readily available means of demonstrating silicone. The major disadvantage of US is that its accuracy depends on the capability of the operator to recognize the abnormality. Although MR imaging outperforms US or mammography in detection of implant rupture, it is not clear that MR imaging is superior in detection of free or residual silicone. The sequelae of noncontained silicone include granuloma formation, fibrosis, and migration. After extrusion from an implant, silicone migrates primarily to local sites, such as the ipsilateral chest wall and axillary nodes. Migration of silicone into the axilla can involve the brachial plexus, resulting in neuropathy. Silicone can also migrate into more distal regions, including the arm and subcutaneous tissues of the abdominal wall. Whatever the source, silicone in breast tissue interferes with the interpretation of mammographic findings.
Index Terms: Breast, MR, 00.121415 • Breast, prostheses, 00.454 • Breast, US, 00.1298 • Silicone, 00.454
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INTRODUCTION
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The use of silicone breast implants has been a controversial and hotly debated topic, with most of the controversy centering on the suggested association between silicone and connective tissue disorders (1). Local adverse effects of noncontained silicone are well documented and include granuloma formation, fibrosis, and migration. Although the need to identify and remove a ruptured silicone implant remains somewhat controversial, the timely removal of a ruptured implant is desirable because delays may increase the degree of silicone leakage and migration, thus making complete removal difficult or impossible.
In this article, we present our experience using ultrasonography (US), magnetic resonance (MR) imaging, and mammography to detect free (direct injection), extracapsular (implant in place), and residual (implant removed) silicone and its associated complications in women with a history of silicone breast implants. The specific topics discussed are examination technique; detection of silicone with US, MR imaging, and mammography; breast augmentation with silicone; and extracapsular spread of silicone.
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EXAMINATION TECHNIQUE
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The images in this article were selected from US, MR, and mammographic images obtained in 448 women with a history of breast implant use who were examined at the Johns Hopkins Hospital between 1993 and 1995. Indications for the examinations included complaints of breast pain and tenderness, neck and shoulder pain, chest wall pain, fibromyalgia, and vague joint and muscle pains in patients with a history of direct silicone injection or a silicone prosthesis placed for breast augmentation or reconstruction.
US was performed with a 5- or 7.5-MHz linear-array transducer (model 128; Acuson, Mountain View, Calif). MR imaging was performed with a 1.5-T unit (Signa; GE Medical Systems, Milwaukee, Wis) with a body coil or a phased-array dedicated breast coil (MRI Devices, Waukesha, Wis). Sequences included fast spin-echo T2-weighted imaging in the axial and sagittal planes, T1-weighted imaging with fat (silicone) suppression (silicone hypointense), and fast spin-echo T2-weighted imaging with water suppression (silicone hyperintense). Mammography was performed with a variety of commercially available mammographic equipment.
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DETECTION OF SILICONE WITH US, MR IMAGING, AND MAMMOGRAPHY
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The US appearance of free silicone is variable. The classic appearance is a highly echogenic pattern of scattered and reverberating echoes with a well-defined anterior margin and loss of detail posteriorly (Fig 1a) (2,3). This pattern has been described as "echogenic noise" or "echodense noise" (3) with an appearance similar to a "snowstorm" (2). Occasionally, this echogenic noise is absent, replaced by acoustic shadowing with the silicone blocking the transmission of sound (Fig 1b). Large to medium-sized conglomerates of free silicone can appear as hypoechoic masses (Fig 1c) (3), which are almost indistinguishable from cysts and are usually surrounded by echogenic noise.
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Figure 1a. US appearance of silicone. (a) Transverse US image of the right axilla in a woman with a 22-year history of silicone implants shows the classic appearance of extracapsular silicone: an area of increased echogenicity anteriorly (solid arrows) and diffuse "white" noise posteriorly (open arrows). (b) Transverse US image of the right axilla in a woman who underwent implant removal after rupture shows a highly echogenic area (arrows) with acoustic shadowing where the silicone blocks sound transmission, obscuring the detail of the pectoral muscle. (c) Transverse US image of the right breast in a woman with a 19-year history of silicone implants shows nearly anechoic conglomerates (arrows) surrounded by echogenic noise (n).
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Figure 1b. US appearance of silicone. (a) Transverse US image of the right axilla in a woman with a 22-year history of silicone implants shows the classic appearance of extracapsular silicone: an area of increased echogenicity anteriorly (solid arrows) and diffuse "white" noise posteriorly (open arrows). (b) Transverse US image of the right axilla in a woman who underwent implant removal after rupture shows a highly echogenic area (arrows) with acoustic shadowing where the silicone blocks sound transmission, obscuring the detail of the pectoral muscle. (c) Transverse US image of the right breast in a woman with a 19-year history of silicone implants shows nearly anechoic conglomerates (arrows) surrounded by echogenic noise (n).
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Figure 1c. US appearance of silicone. (a) Transverse US image of the right axilla in a woman with a 22-year history of silicone implants shows the classic appearance of extracapsular silicone: an area of increased echogenicity anteriorly (solid arrows) and diffuse "white" noise posteriorly (open arrows). (b) Transverse US image of the right axilla in a woman who underwent implant removal after rupture shows a highly echogenic area (arrows) with acoustic shadowing where the silicone blocks sound transmission, obscuring the detail of the pectoral muscle. (c) Transverse US image of the right breast in a woman with a 19-year history of silicone implants shows nearly anechoic conglomerates (arrows) surrounded by echogenic noise (n).
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US is a reliable and cost-effective modality for the detection of residual silicone before and after removal of ruptured silicone implants. The advantages of US include availability, low cost, and ease of correlation with the results of physical examination. The disadvantage of US is that its accuracy depends on the capability of the operator to recognize the abnormality.
MR imaging findings of free silicone include discrete foci of low signal intensity on fat-suppressed T1-weighted images (Fig 2a) and high signal intensity on water-suppressed T2-weighted images (Fig 2b). These foci are identified in continuity with or separate from the implant. Software to perform pulse sequences specific for demonstrating silicone is commercially available (4,5).
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Figure 2a. MR imaging appearance of silicone in a woman with silicone implants. (a) Axial T1-weighted MR image (manually fine-tuned to suppress the silicone peak) of the right breast shows extracapsular silicone posteriorly (arrows), which is of low signal intensity. (b) Axial water-suppressed fast spin-echo T2-weighted MR image shows extracapsular silicone posteriorly (straight arrows), which is of high signal intensity. Note the hypointense thin lines in the interior of the implant (curved arrow), which are compatible with the collapsed elastomer shell and indicative of implant rupture.
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Figure 2b. MR imaging appearance of silicone in a woman with silicone implants. (a) Axial T1-weighted MR image (manually fine-tuned to suppress the silicone peak) of the right breast shows extracapsular silicone posteriorly (arrows), which is of low signal intensity. (b) Axial water-suppressed fast spin-echo T2-weighted MR image shows extracapsular silicone posteriorly (straight arrows), which is of high signal intensity. Note the hypointense thin lines in the interior of the implant (curved arrow), which are compatible with the collapsed elastomer shell and indicative of implant rupture.
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MR imaging is also a reliable modality for the detection of silicone, providing an excellent overview of the breast, the implant (if present), the axilla, and the chest wall. The anatomic mapping is easily communicated to surgeons. A disadvantage of MR imaging is that special sequences are needed to demonstrate residual silicone; these special sequences may not be properly performed or may not be available on all equipment. In addition, even with the proper sequences, scarring can dominate the signal intensity characteristics, making it difficult to be certain that small collections are siliconomas (inflammatory silicone masses). Patients frequently must be prone for the examination, which can be an uncomfortable position for these women. MR imaging is also expensive, costing three times as much as US and nearly four times as much as mammography.
At mammography, silicone appears as dense areas of opacity (Fig 3a). Extracapsular silicone appears as lobular, spherical densities adjacent to or separate from the implant (Fig 3b). Residual silicone from incomplete removal of a ruptured implant can be seen as well-circumscribed or ill-defined densities (Fig 3c).
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Figure 3a. Mammographic appearance of silicone. (a) Oblique mammogram of the left breast in a woman who underwent direct silicone injection more than 30 years earlier shows multiple large and small, dense globules (arrows), which are consistent with free silicone. (b) Oblique mammogram of the right breast in a woman with bilateral silicone implants shows the implant and lobular, spherical densities with fuzzy borders immediately adjacent to the implant (solid arrows) and in the axilla, which are compatible with extracapsular silicone. Note the subtle dark lines representing the implant shell (open arrows). (c) Oblique mammogram of the right breast (same patient as in b) shows two well-circumscribed, opaque masses in the axilla, which are compatible with free silicone.
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Figure 3b. Mammographic appearance of silicone. (a) Oblique mammogram of the left breast in a woman who underwent direct silicone injection more than 30 years earlier shows multiple large and small, dense globules (arrows), which are consistent with free silicone. (b) Oblique mammogram of the right breast in a woman with bilateral silicone implants shows the implant and lobular, spherical densities with fuzzy borders immediately adjacent to the implant (solid arrows) and in the axilla, which are compatible with extracapsular silicone. Note the subtle dark lines representing the implant shell (open arrows). (c) Oblique mammogram of the right breast (same patient as in b) shows two well-circumscribed, opaque masses in the axilla, which are compatible with free silicone.
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Figure 3c. Mammographic appearance of silicone. (a) Oblique mammogram of the left breast in a woman who underwent direct silicone injection more than 30 years earlier shows multiple large and small, dense globules (arrows), which are consistent with free silicone. (b) Oblique mammogram of the right breast in a woman with bilateral silicone implants shows the implant and lobular, spherical densities with fuzzy borders immediately adjacent to the implant (solid arrows) and in the axilla, which are compatible with extracapsular silicone. Note the subtle dark lines representing the implant shell (open arrows). (c) Oblique mammogram of the right breast (same patient as in b) shows two well-circumscribed, opaque masses in the axilla, which are compatible with free silicone.
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Mammography is also a reliable, cost-effective, readily available means of demonstrating free or residual silicone in the breast parenchyma (6). Occasionally, silicone may be indistinguishable from other abnormalities, making interpretation difficult. Therefore, a high level of suspicion for silicone is needed to avoid unnecessary biopsy. Another disadvantage of mammography is that the silicone must be confined to the breast or the axilla (the imaging range of mammography) to be detected. In addition, patients with residual silicone frequently have breast, chest, or shoulder pain and thus may be unable to fully cooperate with mammographic compression. Furthermore, a replaced implant can obscure any residual silicone from the original ruptured implant.
Although comparative studies have shown MR imaging to outperform US or mammography in the detection of implant rupture (7,8), it is not as clear from these studies that MR imaging is superior when the issue is detection of free or residual silicone only. Most studies reported in the literature were performed for the purpose of detecting implant rupture, with extracapsular silicone being only one of several signs used to detect implant rupture. In fact, extracapsular silicone has been shown to be specific (97%) but relatively insensitive (5%) (9) for the detection of rupture, being reported as present in 11%–23% of cases in studies of surgically explanted prostheses (10).
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BREAST AUGMENTATION WITH SILICONE
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Direct Injection
Silicone was initially used for breast augmentation in its liquid form and directly injected into the breast parenchyma (Fig 4). This procedure was performed in the United States in the 1950s and 1960s until the Food and Drug Administration prohibited it in the 1970s due to reports of adverse effects. These adverse effects included lymphadenopathy, infection, formation of granulomatous masses (siliconoma), and fibrosis. The resulting nodularity of this silicone mastopathy made it difficult to differentiate fibrous silicone breast masses from carcinoma at physical examination because both may manifest as a palpable mass. At mammography, these silicone globules appear as multiple radiopaque globules (Fig 5), some with a rim of calcification, which distort the breast parenchyma and thus can easily obscure breast carcinoma.
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Figure 4a. Direct silicone injection for augmentation. (a) Axial water-suppressed fast spin-echo T2-weighted MR image of the right breast shows a single large conglomerate of silicone that mimics an implant in its shape. (b) Sagittal US image at the 11-o'clock position shows a hypoechoic collection with low-level internal echoes (S). Note the area of echogenic noise at the edge of the collection (arrows).
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Figure 4b. Direct silicone injection for augmentation. (a) Axial water-suppressed fast spin-echo T2-weighted MR image of the right breast shows a single large conglomerate of silicone that mimics an implant in its shape. (b) Sagittal US image at the 11-o'clock position shows a hypoechoic collection with low-level internal echoes (S). Note the area of echogenic noise at the edge of the collection (arrows).
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Figure 5a. Direct silicone injection for augmentation. (a) Craniocaudal mammogram of the left breast shows well-defined (arrow) and ill-defined areas of increased opacity, which are compatible with free silicone. (b) Sagittal US image of the left breast at the 9-o'clock position shows echogenic noise obscuring the breast parenchyma in a sheetlike fashion (arrows), which represents free silicone. (c) Sagittal fat-suppressed T1-weighted MR image of the left breast shows multiple masses of low signal intensity (arrow), which are compatible with free silicone.
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Figure 5b. Direct silicone injection for augmentation. (a) Craniocaudal mammogram of the left breast shows well-defined (arrow) and ill-defined areas of increased opacity, which are compatible with free silicone. (b) Sagittal US image of the left breast at the 9-o'clock position shows echogenic noise obscuring the breast parenchyma in a sheetlike fashion (arrows), which represents free silicone. (c) Sagittal fat-suppressed T1-weighted MR image of the left breast shows multiple masses of low signal intensity (arrow), which are compatible with free silicone.
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Figure 5c. Direct silicone injection for augmentation. (a) Craniocaudal mammogram of the left breast shows well-defined (arrow) and ill-defined areas of increased opacity, which are compatible with free silicone. (b) Sagittal US image of the left breast at the 9-o'clock position shows echogenic noise obscuring the breast parenchyma in a sheetlike fashion (arrows), which represents free silicone. (c) Sagittal fat-suppressed T1-weighted MR image of the left breast shows multiple masses of low signal intensity (arrow), which are compatible with free silicone.
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Silicone Implants
Silicone implants were introduced in the 1960s with the production of the Cronin implant (Figs 6, 7). The theory behind the development of the original breast implant was that containing silicone with a barrier would reduce the adverse complications of direct silicone injection while retaining the desirable cosmetic effect of silicone. Unfortunately, the barrier shell used in the manufacture of implants is usually a silicone elastomer, which is semiporous and thus allows small amounts of silicone gel to "bleed" without evidence of gross shell fracture. In addition, the shells are more prone to rupture with increasing implant age (11), resulting in extrusion of large amounts of silicone. The local adverse effects of this free silicone (12) are indistinguishable from those seen in earlier years with the direct injection of silicone.
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Figure 6. Photograph of an early Cronin implant. The prosthesis is shown front down for demonstration purposes. In addition to a thick silicone elastomer shell and a silicone gel of low viscosity, these implants contained a fixative Dacron patch on their dorsal aspect (arrows). During implantation, this side was placed against the chest wall.
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Figure 7a. Inflammatory response to an early Cronin implant in a woman who underwent implant removal after rupture. (a) Oblique mammogram of the right breast shows architectural distortion with an area of increased opacity posteriorly (arrows), findings compatible with silicone or calcifications. (b) US image shows an echogenic shadowing mass (arrows) adjacent to a nearly anechoic collection (arrowheads). At surgery, an inflammatory mass consisting of residual silicone, fragments of the Dacron patch, and pus was found.
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Figure 7b. Inflammatory response to an early Cronin implant in a woman who underwent implant removal after rupture. (a) Oblique mammogram of the right breast shows architectural distortion with an area of increased opacity posteriorly (arrows), findings compatible with silicone or calcifications. (b) US image shows an echogenic shadowing mass (arrows) adjacent to a nearly anechoic collection (arrowheads). At surgery, an inflammatory mass consisting of residual silicone, fragments of the Dacron patch, and pus was found.
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EXTRACAPSULAR SPREAD OF SILICONE
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Silicone Lymphadenopathy and Gel Leakage
Small amounts of silicone may be taken up by the lymphatic system. Indeed, silicone lymphadenopathy in the absence of apparent implant rupture (gel leakage) has been seen (Fig 8).
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Figure 8. Migration of silicone without rupture (gel leakage) in a woman with a 5-year history of polyurethane-covered silicone implants. Sagittal US image of the left axilla shows a focus of echogenic noise (arrows), which is consistent with free silicone.
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Implant Rupture and Extracapsular Silicone
Although the true prevalence of implant rupture is unknown, it appears to vary directly with the age of the implant and inversely with the thickness of the elastomer shell (13), with the thinner shells being more prone to rupture. The prevalence of extracapsular spread of silicone (Figs 9, 10) has been reported to be 11%–23% in studies of surgically removed implants (10).
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Figures 9, 10. (9) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 9-year history of silicone implants. (a) Oblique mammogram of the left breast shows extrusion of silicone superiorly (arrows), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the left breast at the 12-o'clock position shows a hypoechoic mass (arrow) anterior to the implant (S), a finding compatible with extracapsular silicone. (10) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 15-year history of silicone implants. (a) Sagittal T2-weighted MR image of the right breast shows low-signal-intensity bands in the interior of the implant (black arrow), which are compatible with the ruptured elastomer shell. Note the extrusion of silicone beyond the elastomer shell (white arrow), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the right breast at the 6-o'clock position shows an anechoic area, which represents the silicone implant (S). The echogenic lines in the interior of the implant represent the ruptured elastomer shell (arrowhead), and the echogenic noise (N) represents extracapsular silicone. (c) Transverse US image at the 6-o'clock position shows echogenic noise (N), which represents extracapsular silicone (arrows).
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Figures 9, 10. (9) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 9-year history of silicone implants. (a) Oblique mammogram of the left breast shows extrusion of silicone superiorly (arrows), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the left breast at the 12-o'clock position shows a hypoechoic mass (arrow) anterior to the implant (S), a finding compatible with extracapsular silicone. (10) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 15-year history of silicone implants. (a) Sagittal T2-weighted MR image of the right breast shows low-signal-intensity bands in the interior of the implant (black arrow), which are compatible with the ruptured elastomer shell. Note the extrusion of silicone beyond the elastomer shell (white arrow), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the right breast at the 6-o'clock position shows an anechoic area, which represents the silicone implant (S). The echogenic lines in the interior of the implant represent the ruptured elastomer shell (arrowhead), and the echogenic noise (N) represents extracapsular silicone. (c) Transverse US image at the 6-o'clock position shows echogenic noise (N), which represents extracapsular silicone (arrows).
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Figures 9, 10. (9) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 9-year history of silicone implants. (a) Oblique mammogram of the left breast shows extrusion of silicone superiorly (arrows), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the left breast at the 12-o'clock position shows a hypoechoic mass (arrow) anterior to the implant (S), a finding compatible with extracapsular silicone. (10) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 15-year history of silicone implants. (a) Sagittal T2-weighted MR image of the right breast shows low-signal-intensity bands in the interior of the implant (black arrow), which are compatible with the ruptured elastomer shell. Note the extrusion of silicone beyond the elastomer shell (white arrow), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the right breast at the 6-o'clock position shows an anechoic area, which represents the silicone implant (S). The echogenic lines in the interior of the implant represent the ruptured elastomer shell (arrowhead), and the echogenic noise (N) represents extracapsular silicone. (c) Transverse US image at the 6-o'clock position shows echogenic noise (N), which represents extracapsular silicone (arrows).
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Figures 9, 10. (9) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 9-year history of silicone implants. (a) Oblique mammogram of the left breast shows extrusion of silicone superiorly (arrows), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the left breast at the 12-o'clock position shows a hypoechoic mass (arrow) anterior to the implant (S), a finding compatible with extracapsular silicone. (10) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 15-year history of silicone implants. (a) Sagittal T2-weighted MR image of the right breast shows low-signal-intensity bands in the interior of the implant (black arrow), which are compatible with the ruptured elastomer shell. Note the extrusion of silicone beyond the elastomer shell (white arrow), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the right breast at the 6-o'clock position shows an anechoic area, which represents the silicone implant (S). The echogenic lines in the interior of the implant represent the ruptured elastomer shell (arrowhead), and the echogenic noise (N) represents extracapsular silicone. (c) Transverse US image at the 6-o'clock position shows echogenic noise (N), which represents extracapsular silicone (arrows).
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Figures 9, 10. (9) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 9-year history of silicone implants. (a) Oblique mammogram of the left breast shows extrusion of silicone superiorly (arrows), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the left breast at the 12-o'clock position shows a hypoechoic mass (arrow) anterior to the implant (S), a finding compatible with extracapsular silicone. (10) Ruptured silicone implant with extracapsular extension of silicone in a woman with a 15-year history of silicone implants. (a) Sagittal T2-weighted MR image of the right breast shows low-signal-intensity bands in the interior of the implant (black arrow), which are compatible with the ruptured elastomer shell. Note the extrusion of silicone beyond the elastomer shell (white arrow), a finding compatible with extracapsular silicone. (b) Compound sagittal US image of the right breast at the 6-o'clock position shows an anechoic area, which represents the silicone implant (S). The echogenic lines in the interior of the implant represent the ruptured elastomer shell (arrowhead), and the echogenic noise (N) represents extracapsular silicone. (c) Transverse US image at the 6-o'clock position shows echogenic noise (N), which represents extracapsular silicone (arrows).
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Local Adverse Effects of Silicone
Once silicone has extruded from an implant, migration of the silicone is primarily to local sites, such as the ipsilateral chest wall and axillary nodes. Intraductal extension has also been reported, with silicone gel being expressed from the nipple (14). Although initially thought to be inert, silicone has been shown, at least in some of the population, to induce fibrosis (15), which can invade muscle tissue (Fig 11) as well as form siliconomas (Fig 12). The formation of these granulomatous masses represents a natural host response to wall off a foreign substance. Silicone migration into the axilla (Fig 13) can also involve the brachial plexus, resulting in neuropathy.
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Figure 11a. Local migration of silicone between the pectoral muscles in a woman with a history of bilateral silicone implants. (a) Oblique mammogram of the right breast shows the implant in place with extrusion of silicone into the axilla (arrow). The ruptured implant was removed. (b) Sagittal US image of the right breast at the 11-o'clock position obtained 2 years later shows multiple hypoechoic globules (arrows) surrounded by extensive echogenic noise (n), findings compatible with residual silicone. Real-time imaging demonstrated that the residual silicone followed the course of the pectoral muscle. (c) Sagittal water-suppressed fast spin-echo T2-weighted MR image of the right breast shows multiple areas of high signal intensity within the leaves of the pectoral muscle (arrows), findings compatible with silicone.
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Figure 11b. Local migration of silicone between the pectoral muscles in a woman with a history of bilateral silicone implants. (a) Oblique mammogram of the right breast shows the implant in place with extrusion of silicone into the axilla (arrow). The ruptured implant was removed. (b) Sagittal US image of the right breast at the 11-o'clock position obtained 2 years later shows multiple hypoechoic globules (arrows) surrounded by extensive echogenic noise (n), findings compatible with residual silicone. Real-time imaging demonstrated that the residual silicone followed the course of the pectoral muscle. (c) Sagittal water-suppressed fast spin-echo T2-weighted MR image of the right breast shows multiple areas of high signal intensity within the leaves of the pectoral muscle (arrows), findings compatible with silicone.
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Figure 11c. Local migration of silicone between the pectoral muscles in a woman with a history of bilateral silicone implants. (a) Oblique mammogram of the right breast shows the implant in place with extrusion of silicone into the axilla (arrow). The ruptured implant was removed. (b) Sagittal US image of the right breast at the 11-o'clock position obtained 2 years later shows multiple hypoechoic globules (arrows) surrounded by extensive echogenic noise (n), findings compatible with residual silicone. Real-time imaging demonstrated that the residual silicone followed the course of the pectoral muscle. (c) Sagittal water-suppressed fast spin-echo T2-weighted MR image of the right breast shows multiple areas of high signal intensity within the leaves of the pectoral muscle (arrows), findings compatible with silicone.
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Figure 12a. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12b. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12c. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12d. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12e. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12f. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 12g. Siliconomas in a 45-year-old woman with a 12-year history of silicone implants. (a) Oblique mammogram of the right breast shows extrusion of silicone into the axilla (arrow). (b) Oblique mammogram after explantation of the ruptured implant shows two hyperdense masses in the posterior breast (arrows), compatible with residual silicone. A wire on the skin marks a scar. (c) Sagittal fat-suppressed T2-weighted MR image shows a hypointense area in the upper posterior breast (arrow), compatible with residual silicone. (d) US image of the upper outer quadrant of the right breast shows echogenic noise (arrows), compatible with residual silicone. (e) Photograph of the gross specimen shows a clear tentacle joining the cut surfaces of the fibrotic mass (arrow), compatible with residual silicone incorporated into the mass. (f) Photomicrograph (original magnification, x16; hematoxylin-eosin stain) of the siliconoma shows empty vacuoles representing free silicone surrounded by foreign-body giant cells. (g) Photomicrograph (original magnification, x10; hematoxylin-eosin stain) of a pectoral muscle specimen shows empty vacuoles and foreign-body giant cell reaction (arrowheads), compatible with silicone intermixed with the muscle (m).
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Figure 13a. Local migration of silicone to the axilla in a 45-year-old woman with a 12-year history of silicone implants (same patient as in Fig 12). (a) Oblique mammogram of the left breast obtained after removal of the ruptured implant shows dense material in the left axilla (arrows), a finding compatible with residual silicone. A wire on the skin marks a scar. (b) Transverse US image of the left axilla shows an echogenic area with acoustic shadowing (arrows), findings compatible with silicone. An image of the normal right axilla is provided for comparison.
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Figure 13b. Local migration of silicone to the axilla in a 45-year-old woman with a 12-year history of silicone implants (same patient as in Fig 12). (a) Oblique mammogram of the left breast obtained after removal of the ruptured implant shows dense material in the left axilla (arrows), a finding compatible with residual silicone. A wire on the skin marks a scar. (b) Transverse US image of the left axilla shows an echogenic area with acoustic shadowing (arrows), findings compatible with silicone. An image of the normal right axilla is provided for comparison.
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Distal Migration of Silicone
Silicone has also been reported to migrate to more distal areas of the body. Case studies report migration to the arm (Figs 13, 14), which can result in constrictive neuropathy of the radial nerve (16), and migration to the subcutaneous tissues of the lower abdominal wall and the inguinal canal (17). After migration, silicone has been reported to drain through a fistula (18) and produce skin ulcers (19).
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Figure 14a. Distant migration of extracapsular silicone in a 42-year-old woman who experienced left implant rupture 15 years earlier. (a) US image of the left breast shows echogenic noise with acoustic shadowing at 12 o'clock (arrows), findings compatible with residual silicone. (b) Transverse US image of a 10-cm-long palpable ridge in the left elbow (straight arrows) and the left forearm shows echogenic noise, a finding compatible with residual silicone that migrated to the forearm. Note the hypoechoic globule (curved arrow). For orientation, the cortex of the humerus is to the lower right, out of view. sq = subcutaneous tissues. (c) Axial water-suppressed T2-weighted MR images show abnormal high signal intensity along the medial border of the upper arm at the elbow (arrows). (d) Coronal T1-weighted MR image shows increased signal intensity along the medial humeral and ulnar border (arrows).
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Figure 14b. Distant migration of extracapsular silicone in a 42-year-old woman who experienced left implant rupture 15 years earlier. (a) US image of the left breast shows echogenic noise with acoustic shadowing at 12 o'clock (arrows), findings compatible with residual silicone. (b) Transverse US image of a 10-cm-long palpable ridge in the left elbow (straight arrows) and the left forearm shows echogenic noise, a finding compatible with residual silicone that migrated to the forearm. Note the hypoechoic globule (curved arrow). For orientation, the cortex of the humerus is to the lower right, out of view. sq = subcutaneous tissues. (c) Axial water-suppressed T2-weighted MR images show abnormal high signal intensity along the medial border of the upper arm at the elbow (arrows). (d) Coronal T1-weighted MR image shows increased signal intensity along the medial humeral and ulnar border (arrows).
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Figure 14c. Distant migration of extracapsular silicone in a 42-year-old woman who experienced left implant rupture 15 years earlier. (a) US image of the left breast shows echogenic noise with acoustic shadowing at 12 o'clock (arrows), findings compatible with residual silicone. (b) Transverse US image of a 10-cm-long palpable ridge in the left elbow (straight arrows) and the left forearm shows echogenic noise, a finding compatible with residual silicone that migrated to the forearm. Note the hypoechoic globule (curved arrow). For orientation, the cortex of the humerus is to the lower right, out of view. sq = subcutaneous tissues. (c) Axial water-suppressed T2-weighted MR images show abnormal high signal intensity along the medial border of the upper arm at the elbow (arrows). (d) Coronal T1-weighted MR image shows increased signal intensity along the medial humeral and ulnar border (arrows).
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Figure 14d. Distant migration of extracapsular silicone in a 42-year-old woman who experienced left implant rupture 15 years earlier. (a) US image of the left breast shows echogenic noise with acoustic shadowing at 12 o'clock (arrows), findings compatible with residual silicone. (b) Transverse US image of a 10-cm-long palpable ridge in the left elbow (straight arrows) and the left forearm shows echogenic noise, a finding compatible with residual silicone that migrated to the forearm. Note the hypoechoic globule (curved arrow). For orientation, the cortex of the humerus is to the lower right, out of view. sq = subcutaneous tissues. (c) Axial water-suppressed T2-weighted MR images show abnormal high signal intensity along the medial border of the upper arm at the elbow (arrows). (d) Coronal T1-weighted MR image shows increased signal intensity along the medial humeral and ulnar border (arrows).
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CONCLUSIONS
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Whether due to direct injection, gel bleeding, or implant rupture, silicone in breast tissue presents a dilemma for the radiologist because it interferes with the interpretation of mammographic findings (20). Free or residual silicone can mimic or obscure breast carcinoma, making its detection less certain. Although there is some concern that silicone may be carcinogenic, this concern has not yet been substantiated (21).
Searching for residual silicone deposits in the patient with an appropriate history is just one of the steps in the evaluation of the woman with persistent breast and chest wall pain after implant removal. If residual silicone is detected, treatment options include surgical removal if possible; supportive therapy, including local heat, muscle relaxants, and aquatic exercises; and, if symptoms are minimal, a "wait and watch" approach, as symptoms do not always correlate with imaging findings and some women with free silicone are asymptomatic.
Mammography is a reliable, cost-effective, and readily available means of demonstrating silicone. If free silicone is suspected and results of mammography are inconclusive, then evaluation with US or MR imaging may be warranted. US is also a reliable, cost-effective, and readily available modality for the detection of residual silicone. The major disadvantage of US is that its accuracy depends on the capability of the operator to recognize the abnormality. MR imaging has been shown to outperform US or mammography in the detection of implant rupture. However, it is not as clear that MR imaging is superior when the issue is detection of free or residual silicone.
Although the controversy surrounding silicone breast implants has begun to dissipate, imagers will be confronted for years to come by patients with a history of silicone implants in the process of breast cancer detection. Knowledge of the various ways in which residual silicone can manifest is useful so that a complete evaluation of these patients can be made, thus increasing the accuracy of the diagnosis.
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Acknowledgments
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We thank many individuals for their assistance with the preparation of the manuscript, particularly Elias A. Zerhouni, MD, and Janet Kuhlman, MD, for their support of clinical MR imaging studies, Henri Hessels (photography), and the sonographer staff of the Johns Hopkins Hospital, as well as Dan Klepac (photography), Bob Boeye (exhibit design and layout), and Adam Steinmann (exhibit design and layout).
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Footnotes
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CME FEATURE This article meets the criteria for 1.0 credit hour in category 1 of the AMA Physician's Recognition Award. To obtain credit, see the questionnaire on pp S259-S266.
LEARNING OBJECTIVES After reading this article and taking the test, the reader will:
• Understand the clinical findings and sequelae of free silicone.
• Recognize the appearance of free silicone at US, MR imaging, and mammography.
• Understand the advantages and disadvantages of US, MR imaging, and mammography in the detection of free silicone.
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References
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Gabriel SE, O'Fallon WM, Kurland LT, et al. Risk of connective-tissue diseases and other disorders after breast implantation. N Engl J Med 1994; 330:1697-1702.[Abstract/Free Full Text]
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Harris KM, Gannot MA, Shestak K, et al. Silicone implant rupture: detection with US. Radiology 1993; 187:761-768.[Abstract/Free Full Text]
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Rosculet KA, Ikeda DM, Forrest ME, et al. Ruptured gel-filled silicone breast implants: sonographic fin
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Abstract
INTRODUCTION
