Superior vena cava syndrome: a new radiologic approach to diagnosis.

Superior vena cava syndrome, a cause of severe distress, requires careful assessment of its etiology before therapy can be instituted. The diagnostic work-up is varied depending on whether or not the superior vena cava syndrome is associated with a mediastinal mass. Fine needle aspiration biopsy has proved to be of considerable value in the evaluation of superior vena cava syndrome associated with a mediastinal mass.