Computed tomography of mediastinal collaterals in SVC syndrome.

A patient undergoing treatment for abdominal lymphoma presented with a superior vena cava (SVC) syndrome. The presence of a wide mediastinum and "nodular" mediastinal densities on CT presented a diagnostic problem, necessitating thoracotomy. The thoracotomy was negative for tumor or infection. We believe that the presence of an indwelling catheter and mediastinal lipomatosis resulted in the SVC syndrome. The "nodular" densities represented an unusual set of mediastinal collaterals that must be distinguished from adenopathy.