Thyroid hemiagenesis associated with the right aortic arch.

The case of a 38-year-old woman with left thyroid hemiagenesis associated with the right aortic arch is presented. The diagnosis of hemiagenesis was established by isotopic and ultrasonic imaging, and also by angiographically defined absence of the left thyroid arteries. The aortogram revealed a right aortic arch with isolation of the left subclavian artery from the aorta. Although the significance and mechanism of the concomitant development of these anomalies is unknown, this case may be the first report in the literature.