Breast implant rupture

Breast implant ruptures are a recognised complication of a breast implant. It can be intracapsular, when confined by the surrounding fibrous capsule, or extracapsular, when silicone freely extravasates. 

Pathology

After implantation of a silicone or saline breast implant, a fibrous capsule (scar) forms around the implant shell. Implant ruptures may be intracapsular (~85%) or extracapsular (~15%) ⁴.

Intracapsular rupture

An intracapsular rupture occurs when the shell of the implant ruptures but the fibrous capsule formed by the breast remains intact. Silicone does not freely extravasate. This makes it difficult to detect on clinical exam or mammography. Intracapsular rupture is best seen on MRI.

Extracapsular rupture

An extracapsular rupture can lead to a change in the implant contour and may be detected on clinical examination or mammography. An extracapsular rupture implies intracapsular rupture as well ³.

Radiographic features

In an intracapsular rupture, the contents of the implant are contained by the fibrous scar, while the shell appears as a group of wavy lines. This has been termed the "linguine sign" and has been most commonly described with MR imaging ¹. The "keyhole sign", "noose sign" or "teardrop sign" is the appearance of silicone on both sides of a radial fold and also suggests an implant rupture ².

Mammography

Detection of implant ruptures (particularly silicone implant ruptures) are difficult on mammography and detection of intra-capsular silicone ruptures are almost impossible on mammography.

Ultrasound

Ultrasound may demonstrate a "snowstorm appearance" of an extracapsular rupture or the stepladder sign of an intracapsular rupture (a normal implant should usually be anechoic). At the time of writing (2010), the overall sensitivity and specificity rates on ultrasound are thought to range between ~59-85% and ~55-79% respectively ⁷.

Breast MRI

Considered most sensitive for detection of implant rupture. Often does not require contrast if the indication is solely for this purpose.

Non-contrast MRI may also be able to distinguish between silicone and saline implants by using silicone or water only sequences. With the use of multi-planar imaging, MR may also be able to make a distinction between radial folds or real ruptures. A "linguine sign" may be seen which is specific for an intracapsular rupture is due to the free floating shell within the implant. A gross extracapsular rupture is evident as free silicone, separate from the implant, which has extended beyond the implant capsule into the breast or axilla. Free silicone has an increased signal in STIR sequence without any enhancement in T1 weighted fat suppressed sequence.

The salad oil sign has also been described in a double lumen implant rupture, where there is mixing of the saline and silicone, although this on its own is non-specific.