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"Question mark" aorta

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“Question mark” aorta

Q1: What is the most likely diagnosis and how do you confirm your suspicion?

The clinical and radiological picture for this case is compatible with syphilis of the cardiovascular system, characterised by late manifestation as thoracic aortic aneurysm. A history of primary syphilitic infection helps in making the diagnosis. Routine serological tests for syphilis are helpful in confirming the history of spirochaetal infection. Even the venereal disease reference laboratory test might have become negative in this treated case; tests like Treponema pallidum immobilisation evaluation or fluorescent treponemal antibodies absorbed are highly likely positive. As the radiological appearance itself is characteristic,1 together with a definitive history, serological tests in this particular case would be of secondary use only. Precise definition of the aneurysm, on the other hand, can be achieved by echocardiography, imaging studies such as computed tomography or magnetic resonance imaging, and arteriography, if indicated.

Q2: What are the other manifestations of this condition in the same system?

Syphilitic aortitis, the hallmark of cardiovascular syphilis, may present in four ways.1

  1. Asymptomatic aortitis is the most prevalent form and may be unrecognised until necropsy.

  2. Aortic regurgitation or insufficiency occurs as a result of aortic dilatation.

  3. Coronary ostial stenosis occurs in up to 30% of cardiovascular syphilis and frequently coexists with the aforementioned aortic regurgitation. Curiously, despite the frequent manifestation of angina in this condition, clinically apparent myocardial infarction is rare for uncertain reasons.

  4. Aortic aneurysm—usually solitary and saccular, occasionally fusiform—is the least common manifestation.

Q3: What are the principles of management in this condition?

Management in this case is largely dictated by symptoms. Surgical resection might not be indicated if there is no evidence of expanding aneurysm or chest pain. Benzathine penicillin treatment, on the whole, is indicated if syphilitic disease is active or progressive. None the less, it is questionable whether it alters or halts the progression of aortic aneurysm, in the absence of proper evaluation in controlled clinical trials. Jarisch-Herxheimer reaction is a possible inflammatory response after massive death of spirochaetes with initiation of penicillin treatment.

Management of syphilitic cardiovascular disease should have begun at the stage of primary and secondary syphilis. It should be remembered that cardiovascular syphilis develops as a result of untreated and inadequately treated (the majority of cases nowadays) treponemal disease. Aortic aneurysm and aortic regurgitation, once developed, cannot be reversed by antibiotic treatment.

The laboratory proof of syphilis and subsequent computed tomographic evidence of fusiform aneurysm in this patient did support the diagnosis of syphilitic aortitis. We believe that it had been present in this woman three years previously, before penicillin was given. The clinician might have missed the diagnosis of aortitis at that time. It remains speculative whether Jarisch-Herxheimer reaction after treatment made the aneurysm worse. Alternatively, the aortic disease progressed and therefore became more obvious by the time this radiograph was taken this time.

Discussion

“Know syphilis in all its manifestations and relations, and all other things clinical will be added into you” (Sir William Osler, 1891).

The protean multisystem manifestation of this “great imitator disease” was well captured by the above teaching of scholar Osler.

The basic lesion in the tertiary form of cardiovascular syphilis is thought to be that of endarteritis obliterans. Morphological features had been well documented in a necropsy study of 100 such cases.2 Microscopically, all cases showed invariable predilection for the vasa vasorum (of the aorta), which is characterised by medial necrosis. Destruction of the important elastic tissue of media then causes swelling and scarring of the intima, which sets the stage for subsequent aortic dilatation and aneurysm formation. The classical macroscopic appearance of “crow’s foot” or “tree bark” marking2 seen at necropsy reflects the extensive plaque formation along the entire intimal surface of the affected aorta.

Learning points

  • Clinicians need to be familiar with the long forgotten late cardiovascular manifestation of syphilitic infection.

  • Treponemes should be remembered when aortic dilation or aneurysm involves the ascending or thoracic aorta, as opposed to the usual arteriosclerotic abdominal aneurysms.

Symptoms of cardiovascular syphilis typically appear from 10 to 40 years after infection. Routine chest radiography was found to have a sensitivity of 75% in diagnosing luetic thoracic aortic aneurysms among 75 patients who underwent postmortem examination.3 Radiographic features, accompanied by clinical context, give the answer to this diagnosis. Most notable among these are dense shadow, widening, and calcification of the aortic arch4 and linear calcium deposits (“eggshell” calcification outlining the aneurysm5) in ascending aorta.

In the preantibiotic era, these cardiac complications were commonly encountered with late untreated syphilis.2 In the 1990s, reported cases of infectious syphilis had declined substantially. On the other hand, there has been an apparent rising incidence of syphilis infection noted worldwide from surveillance data at the start of the 21st century. It remains to be seen if the late manifestations of cardiovascular syphilis would outnumber the occurrence of rheumatic heart disease in the decades to come. Moreover, whether progression of this “great imitator” to tertiary cardiovascular syphilis would be accelerated as a consequence of HIV induced immunosuppression is of great interest.

Final diagnosis

Thoracic aortic aneurysm as the late manifestation of tertiary syphilis.

References

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