Kommerell's Diverticulum Masquerading in a Right Aortic Arch: A Vascular Surprise.

Kommerell's diverticulum (KD) is a rare vascular anomaly characterized by aneurysmal dilation of the descending aorta at the origin of an aberrant subclavian artery, which can occur in either a right- or left-sided aortic arch. Aberrant right subclavian arteries are found in approximately 0.5% to 2% of the population while aberrant left subclavian arteries are less common, occurring in only 0.04% to 0.4%. KD is associated with aberrant subclavian arteries in 60% to 82% of cases. It is often identified incidentally during imaging studies performed for unrelated reasons, which contributes to the limited understanding of its natural progression. However, KD carries significant risks, including a 53% chance of aneurysm rupture and a 19% incidence of aortic dissection. As a result, surgical management is generally recommended. Although no standardized treatment exists, options include thoracic endovascular aortic repair, hybrid procedures, and open repair. Intervention is typically advised when the orifice diameter exceeds 3 cm and depth exceeds 5 cm due to elevated rupture risk. We present a case of incidentally detected KD originating from a right aortic arch with an aberrant left subclavian artery.