We present a case of a 36-year-old 45 XO Turner syndrome with bicuspid aortic valve, dilatation of the ascending aorta and of the major branches of the aortic arch and multiple cysts of the aortic wall. This was complicated by endarteritis of the base of the aortic arch and production of an intraluminal structure (intra-aortic debris). She also presented reactive pleural effusion and involvement of the pulmonary artery which was complicated by pulmonary embolism. Possible aetiological mechanisms are discussed.