A Rare Case of Superior Vena Cava Syndrome in a Patient With Rheumatoid Arthritis and IgA Nephropathy.

Superior vena cava syndrome (SVCS) is a vascular condition resulting from an impaired venous return to the right atrium. The majority of SVCS cases are caused by mass effect in which extrinsic compression of the vessel leads to obstruction of blood flow. In less common cases of SVCS, thrombus formation and luminal narrowing can result in poor return through the SVC.