Superior vena cava syndrome (SVCS), is a group of symptoms caused by obstruction of the superior vena cava ("SVC"), a short, wide vessel carrying circulating blood into the heart. The majority of cases are caused by malignant tumors within the mediastinum, most commonly lung cancer and non-Hodgkin's lymphoma, directly compressing or invading the SVC wall. Non-malignant causes are increasing in prevalence due to expanding use of intravascular devices (such as permanent central venous catheters and leads for pacemakers and defibrillators), which can result in thrombosis. Other non-malignant causes include benign mediastinal tumors, aortic aneurysm, infections, and fibrosing mediastinitis. Characteristic features are edema (swelling due to excess fluid) of the face and arms and development of swollen collateral veins on the front of the chest wall. Shortness of breath and coughing are quite common symptoms; difficulty swallowing is reported in 11% of cases, headache in 6% and stridor (a high-pitched wheeze) in 4%. The symptoms are rarely life-threatening, though edema of the epiglottis can make breathing difficult, edema of the brain can cause reduced alertness, and in less than 5% of cases of SVCO, severe neurological symptoms or airway compromise are reported. Resolution of superior vena cava syndrome is directly related to the treatment of the underlying compression. Signs and symptoms Shortness of breath is the most common symptom, followed by face or arm swelling. Following are frequent symptoms: Difficulty breathing Headache Facial swelling Venous distention in the neck and distended veins in the upper chest and arms Migraines (especially if unusual to normal) Large decrease in lung capacity Facial swelling after bending/laying down Upper limb edema Lightheadedness Cough Edema (swelling) of the neck, called the collar of Stokes Pemberton's sign Superior vena cava syndrome usually presents more gradually with an increase in symptoms over time as malignancies increase in size or invasiveness. Cause Over 80% of cases are caused by malignant tumors compressing the superior vena cava. Lung cancer, usually small cell carcinoma, comprises 75–80% of these cases and non-Hodgkin lymphoma, most commonly diffuse large B-cell lymphoma, comprises 10–15%. Rare malignant causes include Hodgkin's lymphoma, metastatic cancers, leukemia, leiomyosarcoma of the mediastinal vessels, and plasmocytoma. Syphilis and tuberculosis have also been known to cause superior vena cava syndrome. SVCS can be caused by invasion or compression by a pathological process or by a deep vein thrombosis in the vein itself, although this latter is less common (approximately 35% due to