Chylothorax as a presentation of superior vena cava syndrome in fibrosing mediastinitis: a case report

SESSION TITLE: Thoracic Vasculature Abnormalities SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/11/2023 09:40 am - 10:25 am INTRODUCTION: Fibrosing mediastinitis is a rare condition characterized by the excessive growth of fibrous tissue in the mediastinum. Superior vena cava (SVC) syndrome is a potential complication of fibrosing mediastinitis. Chylothorax in patients with fibrosing mediastinitis and SVC syndrome is an exceedingly rare complication (1). We hereby report a case of SVC stent occlusion in a patient with fibrosing mediastinitis that was complicated by chylothorax. CASE PRESENTATION: A 73-year-old male with a history of idiopathic fibrosing mediastinitis on prednisone with associated pulmonary artery and vein stenosis and recurrent SVC syndrome treated with SVC stent (placed 5 months prior) presented with worsening dyspnea and upper extremity edema. CT angiography showed SVC stent thrombosis, in addition to new moderate right pleural effusion. He underwent right-sided thoracentesis with 1.9 liters of milky fluid removed. Analysis of the fluid revealed triglyceride level of 1010 mg/dl consistent with chylothorax. He also underwent an IR venogram which showed near occlusion of the SVC stent. Pressure measurements across the stent revealed a gradient of 27 mmHg. A microcatheter aspiration pump was used to aspirate a large occluding thrombus. The stent was then dilated with a 14 mm x 6 mm angioplasty balloon. Intravascular ultrasound confirmed a patent lumen. After multidisciplinary discussion, the patient underwent repeat thoracentesis with complete evacuation of chylothorax. In addition, he was started on low-fat diet in addition to octreotide with plans for repeat chest CT in 2 weeks and thoracic duct embolization if conservative measures fail. DISCUSSION: We share a rare presentation of chylothorax in the context of fibrosing mediastinitis with SVC stent occlusion. Chylothorax can result from either anatomic disruption of lymphatic ducts or high central lymphatic pressure (2). Fibrosing mediastinitis results in SVC obstruction, causing central venous pressure to increase. This, in turn, leads to elevated central lymphatic pressure and lymph leakage into the pleural space, resulting in chylothorax. Direct thoracic duct impedance due to fibrosing mediastinitis progression or iatrogenic injury during stent placement are other possible causes. Determining the location of chylothorax can assist in identifying its cause. In our case, chylothorax was detected on the right side, which is the most reported side for this condition. Isolated left-sided chylothorax may occur if the thoracic duct disruption is above the level of the fifth thoracic vertebra (3). However, if the disruption is below this level or if central lymphatic hypertension is the cause, it can lead to right-sided or bilateral chylothorax. A lymphangiogram can be useful in localizing the leak site to guide treatment decisions. In our case, the significant reduction in the rate of effusion accumulation after stent recanalization suggests that SVC stent occlusion played a significant role in the development of this chylothorax. CONCLUSIONS: This case report highlights the rare presentation of chylothorax as a complication of superior vena cava syndrome in a patient with fibrosing mediastinitis. Prompt recognition and management of SVC occlusion can result in the resolution of symptoms and prevent further complications. REFERENCE #1: Warren, William H., Jeffrey S. Altman, and Stephanie A. Gregory. "Chylothorax secondary to obstruction of the superior vena cava: a complication of the LeVeen shunt." Thorax 45.12 (1990): 978-979. REFERENCE #2: Beljaars, Guus H., et al. "Chylothorax, an unusual mechanical complication after central venous cannulation in children." European journal of pediatrics 165 (2006): 646-647. REFERENCE #3: Huggins, J. Terrill. "Chylothorax and cholesterol pleural effusion." Seminars in respiratory and critical care medicine. Vol. 31. No. 06. © Thieme Medical Publishers, 2010. DISCLOSURES: No relevant relationships by Faysal Al-Ghoula No relevant relationships by Hasan Ahmad Hasan Albitar Research support relationship with Erbe Medical Please note: 9/1/2022-present by Ryan Kern, value=Grant/Research No relevant relationships by Sudhesh Kumar No relevant relationships by Tobias Peikert