Silicone breast implants (SBIs) have been extensively studied for their potential complications; however, little attention has been given to the fate of silicone gel that escapes from the implant shell, a phenomenon known as “gel bleeding.” Gel bleeding can occur from both ruptured and intact SBIs, whereby microscopic silicone droplets diffuse through the implant surface [1]. The prevalence of gel bleeding in second-generation SBIs, due to low-viscosity gel within thin and permeable shells, led to the use of highly cohesive gel and multiple layers of shells, which apparently resolve this issue and achieve better aesthetic results [2]. Despite the reduced occurrence of gel bleeding with highly cohesive gel, gel bleeding remains possible, and its incidence is still underestimated [3]. Gel bleeding may lead to capsular contracture and the formation of local granulomas and disseminated granulomatosis, triggering an immune response related to several symptoms of breast implant illness [4,5]. Prompt and reliable diagnostic measures are essential, as the clinical presentation of gel bleeding can easily mimic cancer, presenting as indurated, palpable granulomas in cutaneous tissues, lymph nodes, breasts, and in rare cases, extending to other organs [6]. Most cases of silicone lymphadenopathy occur in ruptured SBIs, and instances of axillary silicone lymphadenopathy caused by gel bleeding with intact SBIs are rare. This case report presents a unique case of axillary silicone lymphadenopathy caused by gel bleeding with intact SBIs.

A 48-year-old woman with a history of hypertension underwent breast augmentation with SBIs 10 years ago. During a routine examination, a dense area was identified in the left axillary region on mammography. Subsequent ultrasound did not reveal any evidence of implant rupture or leakage, but showed a nodule with mixed echogenicity and posterior shadowing in the left axillary area. Further evaluation with magnetic resonance imaging (MRI) revealed a radiographic finding known as the “keyhole sign” in the left implant, indicating the presence of implant wrinkles and gel bleeding, as well as an enlarged lymph node with silicone deposition in the left axillary region (Fig. 1). The patient did not report any specific complaints, but physical examination revealed Baker grade III capsular contracture in both breasts with no palpable mass in both axillary regions (Fig. 2). To confirm the diagnosis of left axillary lymph node enlargement and address the capsular contracture, an excisional biopsy of the lymph node was planned, along with replacement of both SBIs. During surgery, the inserted SBIs (Mentor Siltex, 175 cc Microtextured Round Moderate Profile) were found to be intact with no visible signs of silicone leakage (Fig. 3). The SBIs were replaced with new SBIs (Mentor, MemoryGel, 130 cc Smooth Round Moderate Profile). The breast capsule was also thin and whitish, with no abnormal findings. Ultrasonography performed during surgery identified a mass of approximately 2 × 2 cm with the characteristic appearance associated with the presence of silicone, known as the “snowstorm.” An excisional biopsy was performed, and enlarged, elongated gray lymph nodes were identified (Fig. 4). The patient was discharged one day after surgery with no complications. A histopathological examination revealed the presence of lymph nodes containing large droplets of silicone (Fig. 5). At the 6-month follow-up, she remained in good condition without any specific findings.

Silicone lymphadenopathy is a rare complication that can occur following breast augmentation using SBIs, and it can be challenging to differentiate it from granulomatous lymphadenitis, lipogranuloma, fat necrosis, metastatic carcinomas, and signet ring cell lymphomas [7]. Polydimethylsiloxanes (PDMS) are typically used in SBIs, which are composed of straight chains. PDMS fluids are hydrophobic, or insoluble in water, and are available in a range of viscosities, from thin liquids to thick, non-pourable fluids. These fluids constitute a mixture of different-sized polymer compounds, some of which are smaller than the pores in the implant shell, leading to gel bleeding. Even the latest generation of SBIs, which contain a highly cohesive gel and multiple layers of implant shell, are not immune to gel bleeding. The risk of bleeding increases over time because of the biodegradation of the cohesive gel and the implant shell [8]. These silicone particles can disseminate through lymphatic or hematogenous routes, and may take them several years (typically 6–10 years) to accumulate in the lymph nodes, leading to the development of silicone lymphadenopathy; this explains the latency period between implantation and symptom onset or incidental image findings [7]. In our case, gel bleeding was discovered incidentally during a breast cancer screening 10 years after implantation. Silicone lymphadenopathy has been reported to occur even in cases of unruptured SBIs. However, previous papers and case reports have predominantly focused on ruptured cases, and confirmation was often not obtained in instances where imaging suggested an intact SBI. In our case, breast implant replacement and capsulotomy were performed to address associated capsular contracture, and there was no apparent gross rupture of the breast implant. These findings highlight the possibility of silicone lymphadenopathy resulting from leakage in the absence of implant rupture. We hypothesize that the small pores of the inserted SBIs may have been responsible for the gel bleeding not being visible to the naked eye [9].

Silicone lymphadenopathy can be suspected based on mammography, ultrasonography, and MRI in patients with a history of SBI insertion, and confirmation can be obtained through a pathological examination, such as core needle biopsy, fine needle aspiration, or excisional biopsy. Radiologic imaging is particularly useful in detecting, monitoring, and tracking the disease. The “snowstorm” pattern, first described in the 1990s, remains the most sensitive and specific ultrasonographic indicator of free silicone, which manifests as increased echogenicity, despite the varying appearance of extracapsular silicone on ultrasound [10]. Moreover, mammography can depict silicone granulomas in various forms, such as the presence of dense calcified nodules surrounding the implant [11], and MRI utilizing a silicone-sensitive sequence is the preferred and optimal imaging modality for detecting silicone in both the SBIs and extracapsular areas due to its high sensitivity in detecting silicone [12]. The “keyhole” sign, characterized by invagination of the implant shell and non-contact of the surrounding membranes, can be readily detected on MRI and is a hallmark finding in cases of gel bleeding [13]. In the current case report, imaging studies demonstrated characteristic features of silicone lymphadenopathy, including a “snowstorm” pattern on ultrasound, dense calcification on mammography, and the “keyhole” sign on MRI. Furthermore, MRI revealed rippling of the implant shell in our case. An association has been found between rippling and gel bleeding, and as microtextured implants are known to carry a higher risk of rippling compared to macrotextured implants, it is possible that rippling may have also increased the risk of gel bleeding in our case [14].

The treatment for axillary silicone lymphadenopathy with intact SBIs caused by gel bleeding depends on the patient’s symptoms. In asymptomatic patients, the excision of lymph nodes containing silicone may not be necessary, whereas it may be recommended for symptomatic patients. SBIs should be examined as there is a possibility of rupture even if it is not suspected based on imaging [6]. In the case presented herein, bilateral replacement of SBIs and excisional biopsy of the axillary lymph node were performed.

In conclusion, this case serves as a reminder of the importance of regular follow-up examinations for patients with breast implants. For SBIs placed for any reason, the U.S. Food and Drug Administration advises that patients undergo breast MRI screening at 3 years post-implantation, followed by biennial scans, to detect and manage potential complications early [15]. As demonstrated by this rare case, asymptomatic silicone lymphadenopathy caused by invisible gel bleeding in intact SBIs without rupture can occur. Early detection and prompt management of these complications can prevent further progression and ensure good outcomes for patients. Therefore, it is crucial for patients to understand the importance of regular follow-up examinations and to maintain open communication with their healthcare providers to ensure long-term safety and success following breast augmentation surgery.