[The diagnosis of cystic degeneration of the adventitia (author's transl)].

The clinical picture of cystic degeneration of the adventitia is illustrated by two cases. This usually occurs in a portion of an artery near a joint, most commonly in the popliteal artery. The diagnosis is made in the presence of irregular, intermittent claudication associated with an "hour glass" stenosis of the popliteal artery on the arteriogram, without displacement of the vessel. The aetiology is probably related to herniation of the synovia from the adjacent joint capsule; this explains not only the variable pressure within the cyst in the arterial wall, but also the connection found at operation between the adventitial cyst in the popliteal artery and the joint capsule. Treatment consists in shelling out of the cyst. The prognosis is good and recurrences do not occur.