Facial Swelling Mimicking Anaphylaxis: A Case of Superior Vena Cava Syndrome in the Emergency Department.

Superior vena cava (SVC) syndrome represents clinical manifestations from obstruction of the SVC. It is an uncommon medical emergency that is commonly missed. SVC obstruction is usually caused by extraluminal compression by an intrathoracic mass or intraluminal obstruction from a thrombus.