The microscopic appearances of syphilitic aortitis are as follows.
- Disruption and thickening of the wall of the aorta by an inflammatory infiltration (mainly of lymphocytes and plasma cells), through all layers of the wall of the aorta, and destruction of the e astic aminae of the aortic wall.
- The walls of the vasa vasora in the adventitial layer of the aorta are thickened and undergo endarteritis. There is an infiltration of lymphocytes and plasma cells in the thickened walls of the vasa vasora. This change is similar to that seen in the blood vessels in the periosteum in tertiary syphilis.
This destruction of the wall of the aorta by the inflammatory cell infiltrate and the destruction of the elastic laminae weakens the wall of the aorta, and an aneurysma/ dilatation occurs. These changes to the wall of the aorta are illustrated in Figures below. The hematoxylin and eosin (H & E) stains show the cellular reaction, and the elastic stains show the destruction of the e astic laminae. Figures A, B and C show increasing magnifications: the (a) images are an stain and the (b) images are an elastic stain (VVG).
Figs A, B and C Section of a syphilitic aorta showing destruction of the wall of the aorta. (a) Stained with H&E. (b) Stained with an elastic stain (VVG).
The inflammatory reaction in syphilis involves the cusps of the aortic vaLve. This causes thickening of the valves and fibrosis, which results in shortening of the cusps. This, in turn, leads to inabiLity of the cusps to close completely and to aortic incompetence. The inflammatory infiltration in the intima may also cause occlusion of the ostia of the coronary arteries and myocardial ischemia ( see Fig. below).
♦ This heart has been opened to demonstrate the presence of syphilitic aortitis, thickening of the aortic cusps and the compensatory left ventricular hypertrophy.