Aortic aneurysms associated with tertiary syphilis occur almost always in the thoracic aorta and more often, in the ascending portion. The early changes occur in the media, and in the vessels of the adventitia. The media may show focal, scattered aggregates of lymphocytes and plasma cells, and the small adventitial vessels show the characteristic perivascular lymphocytic cuffing and the endarteritis obliterans common to all stages of syphilis. These changes are associated with focal (but sometimes widespread) loss of elastic fibers, and if there is insufficient or delayed fibrosis, the vessel begins to dilate, leading eventually to as aneurysm. In most cases, however, fibrosis ensues. Tertiary syphilis is featured by a proliferative rather than an exudative response, and there may be extensive aortic fibrosis that involves also the ring of the aortic valve, as well as the cusps. Consequent contraction of the connective tissue creates a wrinkled, nodular change of the aortic intima (tree bark) and may result
in contraction around the coronary ostia, leading to reduced coronary blood flow. There may also be a circumferential increase in the aortic valve ring, leading to thickening/rolling of cusps and aortic insufficiency. To summarize; the effects of tertiary lues may be aortitis, with aneurysm formation, distortion of the intima with stretching of the aortic valve ring, or aortic cusp thickening and aortic valvular insufficiency.

Slide Description: This is a syphilitic aneurysm of the ascending aorta.

IMDEPSAASIAC:

Identify:
Syphilitic aneurysm of the ascending aorta.

Morphology:
Infiltration of lymphocytes and plasma cells into the adventitia, patchy loss of elastic fibers and muscle cells, fibrous scarring.

Disease:
Syphilitic Aneurysm (also called Luetic Aneurysms)

Etiology (main):
Syphilis infection (Treponema pallidum).

Pathogenic mechanism:
Inflammatory involvement begins in the aortic adventitia, particularly involving the vasa vasorum, inducing obliterative endarteritis rimmed by an infiltrate of lymphocytes and plasma cells (called syphilitic aortitis). The narrowing of the lumina of the vasa vasorum causes ischemic injury of the aortic media, with patchy loss of the medial elastic fibers and muscle cells, followed by inflammation and scarring. With destruction of the media, the aorta loses its elastic recoil and may become dilated, producing a syphilitic aneurysm.

Structural changes (specific, gross, and micro):
Grossly, contraction of fibrous scars may lead to wrinkling of intervening segments of aortic intima, called "tree-barking."

Are there any other sites of involvement in the body?
Heart valves, heart hypertrophy

Are there any other diseases where similar changes can be seen?
other aortic aneurysms

Signs / Symptoms:
difficulty swallowing, respriatory difficulty, cough, chest pain

Investigations (confirmation / gauge extent):
In (late stage) cardiovascular syphilis, symptoms and signs are sometimes so typical that a presumptive clinical diagnosis can be made. Syphilitic aortitis is suggested by widening of the aortic root and linear calcification on the walls of the ascending aorta on chest x-ray; a loud, musical tambour quality of the aortic second sound on physical examination. Syphilitic aortic insufficiency occurs without significant aortic stenosis.

Are there any other diseases you have studied where such tests can be positive?

Course of disease progress (complications, monitoring, outcome):
(see lab question 3) With better control of the early stages of syphilis, this complication will be less of a concern. Syphilis in his stage is treated with procaine penicillin G for 21 days.

Highlight 3 important points:
1. Aneurysms can happen in the tertiary stage of syphilis, when obliterative endarteritis occurs.
2. Fibrosis of the valves can lead to valvular insufficiency.
3. In the thoracic ascending aorta.

Lab Questions:

1. In which stage of syphilis are aneurysm seen?
In the third clinical stage (tertiary stage).

2. How is the pathogenesis of atherosclerotic and syphilitic aneurysm different?
- Even when syphilitic aneurysms are complicated by atherosclerosis, the thoracic LOCATION distinguishes them from typical atherosclerotic aneurysms, which rarely affect the aortic arch and never involve the root of the aorta.
- Syphilitic aneurysm involves adventitia, and then involves the media (outside-in), whereas ATH involves intima, and then involves the media (inside-out).

3. What are consequences of syphilitic aneurysm?
(1) encroachment on mediastinal structures
(2) respiratory difficulties caused by encroachment on the lungs and airways
(3) difficulty in swallowing caused by compression of the esophagus
(4) persistent cough from irritation of or pressure on the recurrent laryngeal nerves
(5) pain caused by erosion of bone (i.e., ribs and vertebral bodies)
(6) cardiac disease as the aortic aneurysm leads to aortic valve dilation with valvular insufficiency or narrowing of the coronary ostia causing myocardial ischemia
(7) rupture
*Most patients with syphilitic aneurysms die of heart failure induced by aortic valvular incompetence.

Vignette

Slide Description:
This is opened up syphilitic aneurysm. The intimal surface is irregular and nodular resembling tree bark. Note the enlarged Left ventricle.

Slide Description:
This slide shows the changes of syphilitic aortitis. The intimal surface of the aorta is at the top. Note that the media is highly vascularized and hyperemic, and there are heavy collections of deeply basophilic cells (lymphs and plasma cells) that lie in close proximity to vessels. These show varied degrees of obliterative changes, best seen in the arteriole in the lower left side of the field.

Lab Questions:

1. How does aortic valve get involved in syphilitic process?
Syphilitic aortitis may also cause aortic valve ring dilation, resulting in valvular insufficiency through circumferential stretching of the valve cusps, widening of the commissures between the cusps, and turbulence-induced thickening and rolling of the free margins.

2. What are the causes of aortic regurgitation?
(What is it? Retrograde flow from the aorta into the left ventricle through incompetent aortic cusps...AKA aortic incompetance or insufficiency)
Caused by degeneration of the aortic valves or root, rheumatic heart disease, infective endocarditis, myxomatous degeneration, and trauma.