A 35-year-old woman with Klippel-Trénaunay syndrome developed a popliteal artery aneurysm in the affected extremity. The aneurysm was successfully treated by aneurysmectomy and bypass grafting with autologous saphenous vein. In Klippel-Trénaunay syndrome, angiodysplasia in the venous system is common. However, reports of an arterial aneurysm in a patient with Klippel-Trénaunay syndrome are extremely rare.
