The "aortic nipple" as a sign of impending superior vena caval syndrome.

The development of dilatation of the left superior intercostal vein ("aortic nipple") on chest radiographic studies can be used as a clue to impending superior vena caval syndrome. Two cases are described in which detection of an "aortic nipple" on chest roentgenograms predated the clinical syndrome by seven to ten weeks. Since superior vena caval syndrome is a medical emergency, recognition of signs such as this which may significantly predate the "full-blown" syndrome have far-reaching implications in the care of patients.