Superior Vena Cava Syndrome as the Initial Manifestation of a Thoracic Aortic Aneurysm: A Case Report

Superior vena cava syndrome (SVCS) is caused by impaired venous return from the head, neck, and upper extremities, most commonly due to mediastinal malignancies. Benign causes such as thoracic aortic aneurysm (TAA) are rare, and presentation as SVCS is exceptionally uncommon. We report the case of a 39-year-old chronic smoker presenting with progressive facial, cervical, and upper-extremity swelling and morning orthopnea. Examination revealed prominent chest-wall collateral veins suggestive of SVCS. CT angiography demonstrated a 5.5-cm ascending aortic aneurysm compressing the superior vena cava, with associated venous thrombosis and collateral circulation. A comprehensive work-up excluded infectious, autoimmune, and neoplastic causes, and positron emission tomography (PET) imaging confirmed inflammatory activity around the aneurysm without evidence of malignancy. The patient received anticoagulation and beta-blockade followed by elective surgical repair with restoration of caval flow. Postoperative recovery was uneventful, and histopathology confirmed nonspecific chronic inflammation of the aortic wall. This case highlights that TAA, even when modest in size, may rarely cause SVCS and underscores the importance of considering vascular causes in the differential diagnosis. It further emphasizes the value of timely multidisciplinary evaluation in achieving favorable outcomes.