Diverticula in association with the proximal left subclavian artery: a cause of mediastinal mass lesions.

The case reports of 5 patients with an aortic arch diverticulum associated with the proximal left subclavian artery are presented. In 3 patients, the left subclavian artery arose from a diverticulum off a right aortic arch and traversed the retroesophageal area to the opposite arm. In 1 patient, the left subclavian artery arose from a diverticulum off a left aortic arch; this represents the second instance of this anomaly to be reported in the literature. In 1 patient, the left subclavian artery was not attached to the aorta, and a diverticulum was present in the expected area of attachment. Confusion of these anomalies with solid mediastinal mass lesions and with aortic aneurysms may occur. Treatment is predicted on symptomatology, and resection is usually not indicated. It is necessary to remain cognizant of aortic diverticula and to differentiate them from other mediastinal mass lesions.