Fibromuscular dysplasia and thrombosed aneurysm of the popliteal artery in a child.

A case is reported of bilateral congenital popliteal aneurysms in a 10-year-old girl. Spontaneous thrombosis of the left aneurysm resulted in acute ischemia of the left leg below the knee, and the aneurysm was bypassed with an autogenous saphenous vein graft. Elective resection of the right aneurysm revealed fibromuscular dysplasia, of the medial hyperplasia type, as the cause of the aneurysm. One year after operation, the grafts remained patent, and the patient was asymptomatic.