Abstract: Objective：To report a rare type of aortic arch aneurysm. Methods: Three cases of aortic arch aneurysm derived from the fourth aortic arch were retrospectively analyzed. The pathogenesis and treatment of this type of aortic arch aneurysm were investigated. Results: Most of the aneurysm body was located in the Z2 zone, which was the stem from the fourth aortic arch in the embryonic development period. All of the 3 cases could not be explained by common etiology. We speculated that the cause might be developmental anomaly of the fourth aortic arch. All the 3 aortic arch aneurysms were totally excluded with a covered stent. The technical success rate was 100%. Endoleak of type Ⅰ was seen in one case, which was resolved in a later open surgery. During the follow-up, no type of complications was found. Conclusion:To the best of our knowledge, this is the first report of this type of aortic arch aneurysm. The cause may be developmental anomaly of the fourth aortic arch. Endovascular treatment of this type of aortic arch aneurysm is feasible.

Key words: Aortic aneurysm, thoracic, Congenital abnormalities, Endovascular procedures