Open surgical repair of an isolated aneurysm of the arc of Riolan with celiac artery occlusion and severe superior mesenteric artery stenosis.

The arc of Riolan (AoR), a marginal vessel in the left colon, interconnects the superior and inferior mesenteric arteries. A 65-year-old woman presented with an incidental aneurysmal lesion in the left upper abdomen found on ultrasound. Computed tomography revealed a 27-mm saccular aneurysm in the AoR with occlusion of the celiac artery and severe stenosis of the superior mesenteric artery. Angiography showed that the inferior mesenteric artery provided blood to the perfusion areas of the superior mesenteric artery, celiac artery, and left colon via the AoR. We performed open surgical repair of the aneurysm and reconstruction of the inferior mesenteric artery.