[A case of spontaneous dissection of the cervical carotid artery with pseudoaneurysm].

We experienced the case of a dissecting carotid artery presenting with a pulsatile neck mass. This 60-year-old man was admitted to our department due to a progressive, painful left neck mass. The lesion was diagnosed as a dissecting left internal carotid artery with the subsequent formation of a giant pseudoaneurysm. First, the patient underwent an endovascular treatment using self-expandable stent and Guglielmi detachable coils (GDCs). However, four months after the treatment, recurrence of the pseudoaneurysm happened to him, and he was readmitted to our department. Angiographies revealed an enlargement of the pseudoaneurysm. Then, proximal occlusion of the left internal carotid artery was performed using a balloon and GDCs. Ten months after the second endovascular treatment, since symptoms of the central retinal artery embolism and progression of the mass effect occurred, surgical treatment with trapping and resection of the pseudoaneurysm was performed. We investigated pathologically the surgical specimen and could observe a partial thrombosed wall of the pseudoaneurysm. The multiple neovascular channels in the intima and media layers of the aneurysmal wall could be found, and the vasa vasorum in the adventitia was also noted. We thus suggest that mechanism of the enlargement of the pseudoaneurysm may be due to the retrograde neovascular supplies from the vasa vasorum. As a consequence, repeated bleeding and thrombosis in the dissecting arterial wall may result in the formation of partial thrombosed giant aneurysms.