There have long been questions about a possible association between implants and the risk of developing carcinoma of the breast or other benign or malignant breast tumors. The origin of these concerns was based on the observation that when solid foreign bodies made of various different substances were implanted in rodents, they frequently elicited the development of sarcomas (5,6). This phenomenon, known as the Oppenheimer effect, has never been observed in humans (7,8,9). Numerous epidemiologic studies have investigated the incidence of breast cancer in augmented patients compared to nonaugmented cohorts. These studies unequivocally demonstrate that breast implants are not associated with an increased risk of developing carcinomas or other types of benign or malignant breast tumors (10,11,12). In fact, recently published studies (13,14,15,16) have documented a lower-than-expected incidence of breast cancer in augmented patients (Table 15-1). The observation that augmented women appear to be at a somewhat lower risk of developing breast cancer has led to speculation about possible mechanisms whereby breast implants might inhibit tumorigenesis. Among the hypotheses that have been suggested are that implants cause a heightened immune response, leading to earlier detection and
destruction of precancerous cells; that the compression effect of the implant on surrounding breast tissue results in an alteration of cell growth rate; and that the implant acts as insulation, lowering the ambient temperature of the breast, with subsequent reduction of local tissue metabolic rates (13).

While it clearly has been established that augmented women are not at increased risk for developing breast cancer, due to the frequency of this disease, many augmented women eventually will be diagnosed with breast cancer. This has resulted in persistent and valid concerns about the possible effects of implants on cancer detection (22,23). Conceivably, implants could alter physical examination of the breast, reduce the sensitivity of various imaging modalities, or even interfere with adequate biopsy of suspicious lesions.

Breasts implants, whether submammary, submuscular, or in a dual plane pocket, always reside beneath the parenchyma. For that reason, the presence of the prosthesis alone should not compromise palpation of a lesion. However, there are numerous ways implants may alter physical examination of the breast. Sometimes breast augmentation (particularly when combined with mastopexy) causes parenchymal scarring or areas of fat necrosis. This may result in thickened regions or even discrete lumps palpable on physical examination. If such findings are clinically suspicious, further diagnostic testing is indicated.

A significant number of augmented patients develop capsular contracture. Ordinarily contracture does not interfere with palpation of breast tissue, but occasionally the capsule tears, allowing part of the implant to herniate into adjacent parenchyma; this may result in a palpable (or even visible) mass within the breast (Fig. 15-1). Typically, such a palpable bulge or “knuckle” of the implant is not confusing to plastic surgeons. However, primary care physicians, gynecologists, and nurse practitioners may not be familiar with these findings; when such an abnormal mass is identified, it needs to be differentiated from a pathologic lesion. Calcification of the capsule sometimes occurs, and rigid calcium deposits may be palpated immediately adjacent to the implant. These benign calcifications must be distinguished on both physical examination and mammography from malignant microcalcifications (Fig. 15-2A,B).

One of the recognized complications of silicone gel implants is leakage of filler material, from either gel bleed or frank rupture of the elastomeric shell. When silicone gel leaks from the implant, it may elicit an inflammatory foreign body reaction, leading to fibrosis and sometimes formation of siliconomas. These abnormalities may be palpable adjacent to the implant or in other areas of the breast or chest wall (Fig. 15-3), depending upon where the silicone migrates. Siliconomas typically present as firm, discrete lumps and must be differentiated from other pathologic masses. If a silicone implant ruptures and there is spread of silicone into the breast parenchyma or adjacent structures (extracapsular rupture), it is readily apparent on mammograms (Fig. 15-4). When the silicone gel leaking from the implant remains intracapsular, it may be difficult or impossible to detect on physical examination (silent rupture). This is especially true with newer-generation, more highly cohesive gel-filled implants. Intracapsular rupture can sometimes be diagnosed on mammography (Fig. 15-5) and can reliably be imaged by magnetic resonance imaging (MRI).

Saline implants are inflated with a fill tube inserted via a self-sealing valve on the anterior or posterior surface of the implant. In some patients, particularly those with a thin layer of breast tissue, the valve may be palpable. Generally it will be felt in the central portion of the breast, beneath the nipple areolar complex. Even in cases in which the valve is on the posterior surface, the device can flip over and the valve may be felt. Surgeons sometimes unwittingly perform biopsies only to discover that the palpable mass is a filler valve.

When performing surgical or needle biopsy of a suspected abnormality, caution must be exercised to avoid damaging the implant. In the case of fine-needle aspiration or core needle biopsy, the implant can usually be manipulated away from the area where the sharp
tip is introduced. However, if the lesion is immediately adjacent to the implant, it may be preferable to perform open biopsy to avoid damaging the prosthesis (Fig. 15-6). Core needle biopsy can be problematic because multiple needle insertions may be required to obtain adequate tissue samples, increasing the risk of puncturing the prosthesis. Vacuum-assisted biopsy (Mammotome, MIBB) facilitates biopsy in women with implants (Fig. 15-7) (24,25). With this technique, stereotactic mammography or real-time ultrasonography is used to guide the needle tip adjacent to the suspicious area. The vacuum-assisted biopsy needle can be accurately positioned near the lesion to avoid damaging the implant. Unlike core needle biopsy, the vacuum-assisted biopsy probe is inserted just once into the breast through a single small skin incision. Multiple tissue samples may be taken by rotating the needle aperture and using vacuum assistance. The precision and directional capabilities of vacuum-assisted biopsy make this the preferred technique for percutaneous biopsy in augmented women.

When open biopsy is performed, steps can be taken to minimize the risk of damaging the implant. Dissection is best performed with a blunt-tipped electrocautery. If the surface of the implant is encountered, care should be taken to avoid damaging the shell with any pointed or sharp instrument. If the surgical biopsy also includes a portion of the capsule, it is unnecessary to repair the capsule; a new layer of scar tissue will regenerate over the implant surface.