Diagnostic ultrasound ( PDFDrive )

CHAPTER 21 The Breast 805
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Right
B
Left
FIG. 21.69 Breast Implant Rupture. (A) Classic indings of intracapsular rupture of a single-lumen silicone gel implant are the “stepladder
sign” (arrows). Several linear, horizontally oriented echoes represent folds in a collapsed shell. Several of these are double echogenic lines that
represent the inner and outer surfaces of each fold of the shell (arrows). Asterisk (*) denotes silicone extravasated outside the implant shell but
still within the capsule. (B) Normal left breast implant. Note that the supericial aspect of the unruptured left implant shows the double echogenic
line (white arrowhead) of the shell at the anterior aspect of the silicone gel.
nearly all the silicone gel has extravasated from the shell and
the shell is completely collapsed. Lesser degrees of collapse merely
lead to abnormal, sheetlike separation of the shell inwardly away
from the capsule. In general, there is a continuous spectrum of
intracapsular collapse from involvement of a single radial fold
to complete collapse. Radial folds are quite dynamic, forming
when the patient is in one position, then disappearing when the
patient assumes another position; the apex of radial folds therefore
is prone to fatigue fractures. Because radial folds normally contain
anechoic peri-implant efusion that is identical to silicone gel in
echogenicity, for any individual radial fold, it is impossible to
know whether the luid within the fold is normal efusion or
extravasated silicone gel from a fatigue fracture at the apex of
the fold, unless the extravasated gel within the fold becomes
hyperechoic. Radial folds should be considered normal unless
they contain hyperechoic contents (“snowstorm” appearance).
In extracapsular rupture there is a tear in the capsule as well
as in the shell, and silicone gel extravasates into the breast tissues
outside the capsule. By deinition, all cases of extracapsular rupture
must be preceded by intracapsular rupture, although in many
cases the intracapsular component is diicult to demonstrate
sonographically. he classic inding is the silicone granuloma
with a snowstorm appearance. Such granulomas are markedly
hyperechoic and well circumscribed anteriorly but have an
incoherent, “dirty” shadow posteriorly. Silicone granulomas can
occur supericial to implants (Fig. 21.70A), but they most oten
occur at the edges of the implant, where the shell is thinnest and
where fatigue fractures are more likely to occur (Fig. 21.70B).
In certain cases, extravasated silicone gel forms a thin sheet over
the outer surface of the implant rather than a discrete mass (Fig.
21.70C). In other cases, extravasated silicone gel can migrate
away from the edge of the implant to the axilla, chest wall, back,
or abdominal wall (Fig. 21.70D). Extravasated silicone gel can
be picked up and carried by lymphatic vessels into the axillary
lymph nodes, where it accumulates from the medullary sinuses
within the mediastinum of the lymph node outwardly. Early
accumulation of silicone gel within lymph nodes can be diicult
to detect, although gel in the lymph node hilum will cause a
subtle, dirty-appearing shadow. 72 As more silicone gel accumulates,
the diagnosis of silicone gel accumulation within the lymph node
becomes more obvious, and dirty shadowing arises from the
entire lymph node (Fig. 21.70E).
Silicone granulomas have a spectrum of appearances. Not all
have the classic snowstorm appearance. Large, acute accumulations
of extracapsular silicone gel can appear complex and cystic (Fig.
21.71A). Over time, these may become solid appearing and
isoechoic (Fig. 21.71B). he classic snowstorm appearance
develops late, ater the solid, isoechoic phase. Very late in the
history of a silicone granuloma, so much foreign body granuloma
may develop that the lesion can become hypoechoic, causing
architectural distortion and more intense acoustic shadowing—
indings that simulate those of stellate breast malignant lesions