Extracapsular rupture of a silicone breast implant

Case courtesy Dr. Sergio Dromi

Screening mammogram (left breast CC view):
Screening mammogram (right breast CC view):

The screening mammogram shows asymmetric areas of patchy hyperdensity in the left breast compared to the right. There are also bilateral implants, which appear very dense suggesting silicone rather than saline. Some of the areas of density in the left breast have a globular, mass-like appearance.

Breast MRI:

There are bilateral silicone implants, the composition of which can be confirmed by using a water and fat suppressed sequence. In this sequence, saline (water) signal will suppress and appear dark, whereas silicone implants will remain bright.

The MRI shows extensive patchy linear and mass-like areas of T2 hyperintensity within the anterior and medial breast. On the water and fat suppressed sequence, the signal intensity of the parenchymal abnormalities roughly match the signal of the silicone implants.

These findings are compatible with extracapsular rupture of a silicone breast implant with free silicone in the breast parenchyma.

The MRI, however, appears to show an intact left breast implant. There is no evidence of linguine sign:
linguine sign (Radiopedia)

or keyhole sign:
keyhole sign (Applied Radiology)

So what's going on?
This patient has already undergone revision of the ruptured implant and a new implant has been placed.

What's the difference between intra- and extracapsular rupture? After placing the silicone implant, the surrounding tissue forms a fibrotic capsule that contains the implant. Often, when the implant itself ruptures, the spilled silicone stays within this fibrotic capsule. The ruptured bag of the implant flops around within the contained pocket of silicone, giving the linguine or keyhole signs. This is called intracapsular rupture. If the fibrous tissue capsule also ruptures, silicone can spill into the breast parenchyma, giving an appearance as in our case.

When extracapsular rupture occurs, silicone can also be taken up by the lymphatics and concentrated in axillary lymph nodes, giving a characteristic appearance on ultrasound with dirty shadowing or "snowstorm" appearance:

snowstorm lymph node (Ultrasoundpedia)

More reading: Breast Implant Rupture - Radiopedia

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