The Augmented and Reconstructed Breast

Breast Implants

Breast implants are medical prostheses placed within the breast tissue or under the pectoralis muscle to either augment the breast for cosmesis or reconstruct the breast after cancer surgery, trauma, or for correction of a congenital malformation. Implants were first introduced in the 1960s and have undergone considerable changes and improvements over the last several decades. The U.S. Food and Drug Administration (FDA) has approved two types of implants: saline and silicone.

Both saline and silicone implants consist of a textured or smooth elastomer silicone outer shell filled with either a saline solution or silicone gel. Normal implants have an oval shape and smooth contour on mammography. Saline prostheses will appear radiolucent with a prominent valve, usually seen in a periareolar location. This valve allows for volume adjustment during and after implant placement ( Fig. 18.1A ). Silicone implants with either viscous or cohesive gel filler are radiopaque on mammography ( Fig. 18.1B ) and lack the valve seen with saline implants. Double lumen or expandable implants with various combinations of saline and silicone inner and outer lumens are less commonly encountered, as their complicated construction has been linked to higher rates of implant failure. These dual lumen implants allow gradual expansion and volume adjustment of the saline lumen through a subcutaneous valve after placement—a useful advantage for breast reconstruction ( Box 18.1 ).

The placement of any type of implant will trigger an inflammatory response, which is a normal part of the healing process. The body recognizes the prosthesis as a foreign object and attempts to isolate it by surrounding the implant with a thin, collagenous fibrous capsule. This barrier is a normal finding around all implants, is harmless in most women, and helps stabilize the implant position. The capsule usually is not discernible on conventional imaging unless it calcifies, which may occur in up to 16% of women with implants. Capsular calcifications on mammography vary in morphology from coarse, plaque-like calcifications to amorphous or pleomorphic calcifications along the implant margin.

Implant location or position is defined by its anatomic relationship to the pectoralis muscle. Prepectoral (also known as subglandular) implants are in front of the pectoralis muscle, while retropectoral (also known as subpectoral) implant are behind the pectoralis muscle (see Fig. 18.1A–B ). Because the presence of implants may obscure up to 25% of breast tissue on mammography, four implant-displaced (ID) or Eklund views in addition to the four standard craniocaudal (CC) and mediolateral oblique (MLO) views are recommended to visualize as much tissue as possible. The ID technique requires displacing the implant posteriorly and compressing the anterior tissue, allowing for improved visualization of the native breast tissue ( Fig. 18.2A–B ). ID views are easier to acquire in women with retropectoral implants but are not as successful if marked capsular calcifications or capsular contracture are present ( Box 18.2 ).

Implant Risks and Complications

Silicone implants are considered safe, but as with any medical device, there are associated risks and complications that are important to recognize. In the 1980s, there was growing concern over silicone implant rupture and its potential association with immunologic disorders. In response, the FDA issued a moratorium on use of silicone breast implants in 1992, which was subsequently lifted in 2006, after a number of published studies revealed no connection to systemic disease.

More recently, breast implant–associated anaplastic large cell lymphoma (BIA-ALCL) has emerged as a potential risk of the newer-generation silicone cohesive gel implants, particularly the textured variety. BIA-ALCL is a rare, T-cell lymphoma, with a current estimated risk of approximately 1 in 35,000 women with implants by age 50, with risk increasing with age. The pathogenesis is unknown, but theories suggest that it may be associated chronic peri-implant inflammation in a genetically susceptible host. The most common presentation is a large fluid collection surrounding the implant greater than 1 year after implant placement. Less commonly, it can present as a capsular mass with or without associated fluid collection ( Fig. 18.3 ). Clinical signs and symptoms include rapid swelling of the affected breast, palpable mass, skin erythema, or ulceration. The presence of a delayed moderate or large fluid collection surrounding the implant greater than 1 year after placement should be further investigated with fluid aspiration to evaluate for infection or BIA-ALCL. BIA-ALCL is uniformly and strongly positive for the CD30 tumor marker and negative for anaplastic lymphoma kinase (ALK). On imaging, ultrasound is more sensitive than mammography for detecting fluid collections and associated capsular masses. Prognosis is dependent on stage at diagnosis; thus, magnetic resonance imaging (MRI) or positron emission tomography–computed tomography (PET-CT) may be helpful for staging ( Box 18.3 ).