Circumflex retroesophageal right aortic arch simulating mediastinal tumor or dissecting aneurysm.

The authors present three cases of circumflex right aortic arch, a retroesophageal arch in which the aorta crosses from right to left behind the esophagus to descend on the left side. The findings on the frontal chest films resembled those of a left arch with mediastinal widening, simulating a mass. Aortography revealed four-vessel branching of the arch vessels, typical of right aortic arch with aberrant left subclavian artery. Computed tomography and barium studies of the esophagus demonstrated the retroesophageal course of the aorta. In two patients, obstruction of the thoracic portion of the left subclavian artery resulted in differences in blood pressure and pulse between the arms, supporting the clinical impression of dissecting aortic aneurysm.