Spectrum of Imaging Findings in the Silicone-Injected Breast

Abstract

Sir: Silicone injection for breast augmentation was commonly performed in the 1960s. This procedure was subsequently abandoned and replaced by silicone breast prostheses. Non–medical grade silicone breast injection for augmentation is still being performed in the United States, Asia, and South America. Familiarity with the associated imaging findings is important for mammographic interpretation and surgical management. The presence of injected silicone may first be discovered on mammography. High-density silicone granulomas are the hallmark of silicone-injected breasts (Fig. 1).Fig. 1.: Bilateral craniocaudal views of a 57-year-old woman following free silicone injection demonstrate multiple silicone granulomas in a mixed pattern.Technically, mammography may be difficult to perform in patients who have undergone silicone injection for augmentation. Compression of the breasts is limited because the silicone-injected breast increases in thickness. Penetration of the silicone-injected breast requires increased radiation exposure. Several mammographic patterns can be seen on mammography, including macronodular, micronodular, and mixed patterns.1 Silicone granulomas with calcified rims may develop. Another mammographic appearance is a single conglomerate dense mass. Occasionally, an implant will be placed in the silicone-injected breast that further obscures breast tissue. Differentiation of injected silicone from extracapsular rupture of a silicone implant may be challenging. Extracapsular silicone from breast implant rupture usually presents mammographically as larger, rounder globules of silicone that are less numerous compared with injected silicone. A variety of postsurgical changes related to treatment by subcutaneous mastectomy or reduction mammaplasty may be evident on mammography. After subcutaneous mastectomy, residual silicone may still be evident (Fig. 2). In all cases, a significant amount of breast tissue is obscured by the silicone, and it is virtually impossible to detect malignancy on mammography.Fig. 2.: Craniocaudal (left) and mediolateral oblique (right) views of a 71-year-old woman following right subcutaneous mastectomy for treatment of pain related to silicone granulomas demonstrate high-density material within the anterior portion of the breast and thickening and retraction of the skin related to subcutaneous mastectomy.Mammography detects silicone lymphadenitis as enlarged, very dense nodes indistinguishable from lymph node involvement with breast cancer metastasis or other metastatic tumors. Silicone migration into the abdomen may be apparent on mammography. The sonographic appearance of free silicone in the breast was described by Harris et al. as a “snowstorm” appearance that obscures the posterior breast tissue.2 Chest computed tomography images the breasts and may identify injected breast silicone (Fig. 3). Multiple, round, dense nodules are evident in the silicone-injected breast on computed tomographic scanning.Fig. 3.: Computed tomographic scan of a 63-year-old woman following silicone injection demonstrates multiple calcified nodules in the left breast (small white arrows; above, right).Magnetic resonance imaging findings include multiple masses of low signal intensity on T1-weighted images.3 Because of the differential magnetic resonance imaging properties of injected silicone and breast cancer, magnetic resonance imaging may also incidentally detect breast cancer obscured on mammography by dense overlying silicone (Fig. 4).4Fig. 4.: T2-weighted magnetic resonance imaging scan of a 64-year-old woman following silicone injection demonstrates high-intensity, well-circumscribed white nodules in the posterior breast (arrow) representing injected silicone. There is also an ill-defined darker mass in the anterior breast (arrowhead) suggestive of breast cancer.Management of the silicone-injected breasts is not standardized. Treatment regimens include bilateral subcutaneous mastectomy with placement of subpectoral implants, unilateral subcutaneous mastectomy, or simple mastectomy.5 Overlap of symptoms and clinical findings may make diagnosis of breast cancer extraordinarily difficult in the silicone-injected breast. Medical grade injected silicone for breast augmentation was abandoned in the United States many years ago. Patients continue to undergo non–medical grade silicone injection for breast augmentation and may present to plastic surgeons for treatment. Evaluation using various imaging modalities enhances surgical evaluation and management of the silicone-injected breast. Magnetic resonance imaging may be most helpful in excluding underlying breast cancer. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. A. Jill Leibman, M.D. Monika Misra, M.D. Department of Radiology Jacobi Medical Center, and Albert Einstein College of Medicine Bronx, N.Y.