Vasculo-Behçet's disease: immunological study of the formation of aneurysm.

We report two patients with vasculo-Behçet's disease who had femoral and popliteal aneurysms. The resected aneurysms and occluded distal arteries were studied clinicopathologically. The most interesting features were prominent fibrosis of the adventitia including the surrounding tissue, venous occlusion, perivasculitis and deposits of C3, C4 and immunoglobulins (IgA, IgG and IgM) in the arterial wall and surrounding tissue. These findings indicate that the formation of aneurysm in vasculo-Behçet's disease is caused by destruction of the intimal and outer side of the arterial wall.