Ductus diverticulum is either a remnant of the ductus arteriosus or the right dorsal aortic root. The most common diagnosis is the differentiation of an aortic isthmus pseudoaneurysm from a type III ductal diverticulum. Both aortic entities occur at roughly the same anatomical location often leading to diagnostic confusion. Aortic dissection should be considered if it is Takayasu's disease. We are reporting the case of a 31-year-old woman with chest pain and muscle weakness, functional impotence of the left upper limb with intermittent palpitations. Thoraco-abdominal CT angiography was in favor of inflammatory arteritis of the thoraco-abdominal aorta, common carotids and the left subclavian artery. Sub-occlusive stenosis of the left axillary artery was noted, in favor of Takayasu disease. There was an aspect of aortic ductus diverticulum type III, 24mm from the emergence of the subclavian artery simulating aortic dissection or ulceration of the aortic isthmus. An electrocardiogram revealed Wolff Parkinson White syndrome with left lateral Kent. There was good clinical outcome after immunosuppressive drugs and antiarrhythmic therapy.