Anterior mediastinal mass-luckily is not cancer!

Abstract

LEARNING OBJECTIVE 1: Recognize that Silicone implant rupture can migrate. LEARNING OBJECTIVE 2: Recognize that Silicone induced lymphadenopathy can be confused for malignancy. CASE: A 56 year-old nonsmoking women with a history of rheumatoid arthritis, breast augmentation surgery followed by explant and silicone exchange due to implant rupture many years prior, presented with complaints of exertional dyspnea and palpitations for 1 month. Prior outpatient evaluation including echocardiography, exercise stress test and pulmonary function tests were unremarkable. During one of her outpatient visits she was found to be hypoxic and was sent to the emergency department (ED) for further evaluation. In ED, her vital signs and physical examination were unremarkable. Initial cardiac evaluation was negative for acute coronary syndrome. Computed tomography (CT) chest ruled out pulmonary embolism but revealed a 2.7 cm anterior mediastinal mass with mediastinal adenopathy along with a left supraclavicular adenopathy. The patient was known to have left supraclavicular adenopathy, for which she underwent FNA that was negative for malignancy, a month prior to admission. During the hospital course episodes of supraventricular tachycardia were seen on telemetry that were controlled with Metoprolol. No episode of hypoxia or exertional drop in oxygen saturation was noted during her hospital stay. CT guided core needle biopsy of the anterior mediastinal mass was inconclusive and revealed necrosis and debris. Subsequently, due to increased concern for malignancy, thoracic surgery was involved and complete excision of the mediastinal mass and supraclavicular lymph node was performed by video-assisted thoracoscopic surgery (VATS). Left upper lung wedge resection was also performed due to the adhesions between mediastinal area and lung. Review of the surgical specimens showed no malignancy but rather fibrosis and foreign body giant cell reaction to lipoid like material compatible with silicone. The lung biopsy revealed the same reaction predominantly within the alveolar capillaries and perivascular regions consistent with silicone emboli. DISCUSSION: Silicone implants are widely used either for breast reconstruction surgery or for breast augmentation. Direct silicone injections into the breast tissue for augmentation were discontinued in the United States because of the widespread occurrence of adverse events, including the migration of silicone to distant sites. Implants were considered technically superior as the envelope and the scar capsule were designed to retain the gel and to prevent migration. However, Implant rupture can still occur and is often a late complication that can be either: intra capsular, extra capsular or migrated gel. Most ruptures have no obvious traumatic cause. The frequency of asymptomatic rupture is around 0.2-4 %. The silicone gel that migrates beyond the breast tissue incites an inflammatory reaction and silicone granuloma formation regulated by cell mediated immune reactivity and T cell stimulation. Silicone gel entering the lymphatics, either through overt implant rupture or slow leakage across the intact outer shell can result in regional migration to the draining lymph node basins. Migration may not be limited to the corresponding axillary lymph nodes and can spread to more distant sites such as internal mammary, inguinal nodes, and abdominal wall. Silicone leak can also spread in a retrograde direction once it reaches the jugular-subclavian venous confluence. The development of lymphadenopathy may raise concerns regarding new or recurrent malignancy. In addition, positron emission topography (PET) scanning may demonstrate positive FDG uptake in silicone-induced lymphadenopathy and further heighten the suspicion of malignant disease. Magnetic resonance imaging (MRI) is the imaging study of choice in diagnosing implant rupture. Individual plastic surgeons have recommended prophylactic removal of implants within 8 years of implantation to avoid the increased risk of rupture as the implants ages. Few have advised that in the absence of definitive studies, the source of silicone should be removed from patients with symptoms of systemic disease. Breast implant rupture should always be treated aggressively to prevent extra capsular spread, distant migration and inflammatory reactions. However it is not recommended to routinely screen women for implant leak without symptoms. Our case adds to a growing awareness of this phenomenon and emphasizes the need for continued vigilance for signs and symptoms of migration and to recognize silicone migration as a cause of lymphadenopathy in patients with breast implants, not to be confused with metastatic cancer or other malignancy or infectious disease.