Breast implant intra and extracapsular rupture associated with axillary and internal mammary silicone lymphadenopathy

Clinical History

A 30-years-old woman with breast augmentation implants (PIP) presented to our Breast Pathology Clinic with the diagnostic of right axillary adenomegalies in an ultrasound performed in another institution. There was no history of trauma or breast nodular lesions.

Imaging Findings

Ultrasound revealed multiple linear and curvilinear lines traversing through the interior of the right implant at various levels (stepladder sign) (Fig. 1). There were also some adenomegalies presenting as echogenic nodules with a well-defined anterior margin and dirty posterior shadowing (snowstorm sign) (Fig. 2) in the right axillary zone.

At MRI the right breast implant showed an inner wall with ondulating wavy margin and multiple linear low signal lines floating in the gel (linguine sign, noose sign and subcapsular line sign) (Fig. 3). Marked irregularity and deformation of the outer contour of the implant with silicone outside it was also present (Fig. 4). The presence of silicone outside the implant was confirmed by silicone-suppressed MR-imaging (Fig. 5). Right axillary and right internal mammary biopsy-proven silicone lymphadenopathies (Fig. 6-7) were also evident. No suspicious areas of contrast uptake in the breast were identified. Silicone adenopathies had no peculiar contrast uptake kinetics, showing a progressive pattern (Fig. 8).

Discussion

Implant rupture is recognized as an important and common complication. Risk of rupture is directly related to the age of the implant and is inversely related to the thickness of the elastomer shell. Silicone implant rupture can be classified as intracapsular or extracapsular depending on the location of ruptured silicone with respect to the fibrous capsule. Most implant ruptures (77–89%) are intracapsular [1]. Extracapsular rupture is defined as rupture of the implant envelope and the surrounding fibrous capsule, with silicone extending into adjacent breast tissue [2]

Ultrasound detects silicone implant rupture with a sensitivity of 50–77% and specificity of 55–84% [1]. The most reliable sign of intracapsular rupture is the visualization of multiple linear or curvilinear lines traversing through the interior of the implant at various levels, termed the “stepladder sign” [1]. Free silicone appears on ultrasound as an echogenic nodule with an anterior well-defined margin and a dirty posterior shadowing ("snowstorm sign") within either the breast parenchyma or even the axillary lymph nodes. Snowstorm sign is completely predictive of rupture but has a low sensitivity [3].

MRI is the most accurate method for evaluating implant integrity [4, 5]. Breast implants normally show a smooth contour with normal appearances of the outer fibrous margin and inner radial patterns. The hallmark of intracapsular rupture on MRI is the linguine sign, representing layers of collapsed shell floating in silicone gel contained by the fibrous capsule [1]. The “sub-capsular line” sign is a dark line seen just below the outer implant capsule, which represents a thin layer of silicone interposed between shell and fibrous capsule. The “noose sign” represents focal invagination of implant shell caused by small collection of silicone outside the shell. Collectively, these signs represent silicone outside the implant shell but contained within the fibrous capsule [1].
Extracapsular rupture is evident on MRI 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 T2-STIR weighted sequence without any enhancement in T1 weighted fat-suppressed sequence [2]. Silicone-only (STIR sequence + Water suppression) sequences (can also include silicone-saturation sequences) should be included in breast implant MRI protocol to facilitate the distinction between water and silicone.

With the increasing prevalence of breast augmentation, implant rupture is nowadays a common finding in breast studies. It’s of paramount importance to be familiar with the spectrum of its appearances, in particular their typical signs shown here.

Differential Diagnosis List

Final Diagnosis

Breast implant intra and extracapsular rupture with silicone lymphadenopathies.

URL:	https://www.eurorad.org/case/11602
DOI:	10.1594/EURORAD/CASE.11602
ISSN:	1563-4086