ARTICLE
Abdominal aortic aneurysm (AAA) is a common finding in aged patients
[1, 2], with a mortality estimated at 15,000 cases per year in the USA
[3]. The most common etiology being atherosclerosis (up to 95% of cases)
[4, 5], an infectious origin has also been described [6, 7] and is considered
unusual. Syphilis may be responsible for thoracic aortic aneurysms (50%
located in the ascending aorta, 30-40% in the aortic arch, 10-15% in the
descending aorta [7]), but a syphilitic aortitis in the abdominal portion
is exceptional, and described in less than 5% of all syphilitic aneurysms
[7]. The apparent decrease in luetic infections and the wide use of antibiotics
have significantly reduced the observed cases of primary syphilis, and
late manifestations of the infection may be misdiagnosed. Moreover, syphilitic
aneurysms show a CT scan pattern quite similar to "inflammatory" aneurysms,
of atherosclerotic etiology, characterized by an intense perianeurysmal
fibrosis and observed with higher frequencies (5-10% of all AAAs [8, 9]).
We here report a case of luetic aneurysm of the abdominal aorta, and discuss
its differential diagnosis and treatment.
Case report
A white man aged 60 yrs, with a history of abdominal pain with lumbar
irradiation, urine retention, profuse sweating and weakness for 3 days,
was admitted to our department from the emergency room. The patient reported
a family history of ischemic heart disease, arterial hypertension and
diabetes mellitus; he was hypertensive but his condition was well controlled
by medical treatment. No history of past sexually transmitted diseases
was reported. Physical examination revealed a pulsating abdominal mass.
Echodoppler and CT scan of the abdomen and aortography showed an aneurysm
originating from the juxtarenal aorta, extending caudally for 9 cm and
involving the right common iliac artery. The aneurysmal wall appeared
thickened at CT scan, suggesting an "inflammatory" aneurysm; no signs
of rupture or fissuration were found (Fig.
1).
The VDRL test, performed routinely in our hospital, was strongly positive,
so further tests were carried out obtaining the following results: TPI
(Nelson and Mayer) 80% (normal value < 50%), FTA++, TPHA+,
IgM SPHA, specific IgM 55 mg/100 ml (normal values 69-250).
A middle total laparotomy was performed and
the abdominal aorta was exposed. An intense perianeurysmal flogosis was
found, extending to the fourth portion of the duodenum and the first jejunal
loop, making it particularly difficult to access the aneurysmal neck.
Aneurysmectomy and aorto-biiliac graft replacement was performed. The
postoperative course was uneventful, except for a protracted need of vescical
catheterization.
The definitive histology showed a typical pattern of luetic aortitis
(Fig. 2): lymphocytic
and plasmacellular inflammatory infiltrate, in micronodular pattern, mostly
localized around the vasa vasorum of the aortic wall. This infiltrate
was also very evident in the external side of the aortic wall, extending
to the vessels and the periadventitial fat. The patient was discharged
15 days after the operation; therapy with erythromycin, started preoperatively,
was continued for the next 30 days. At follow-up, the patient is alive
and well 34 months after intervention.
Discussion
The incidence of mycotic aneurysms, although low (1-3% of all AAAs),
appears to be increasing [11, 12] if a bacterial origin is considered.
Observed mainly in the thoracic aorta [7], luetic aneurysms of the abdominal
aorta were considered quite uncommon in the pre-antibiotic era [13-15];
and they are even not described in recent literature.
The symptoms reported and the finding of an intense parietal and perivascular
inflammation make these aneurysms very similar to the "inflammatory" type
described with increasing frequency in recent years [8, 9], so a differential
diagnosis is mandatory.
Abdominal and lumbar pain due to inflammatory reaction in the perianeurysmal
nervous structures is a common finding (80% of cases) and may simulate
fissuration or impending rupture [16]. Edema of the lower extremities
due to inferior vena cava obstruction, gastric outlet impairment from
duodenal compression, hydroureteronephrosis from ureteral compression
and urinary retention (as in our case) secondary to the involvement of
periaortic nervous plexus have also been described [17]. Ultrasound or
CT scan have a primary role in detecting a perianeurysmal inflammatory
reaction and excluding signs of fissuration or rupture.
The severity and the extension of the perianeurysmal
fibrosis involving the ureters, the small bowel, the sigmoid colon, or
the inferior vena cava may be a serious intraoperative problem, because
of the high risk of accidental injuries to these structures [18, 19].
In our case, dissecting the aneurysm from the duodenum was very difficult,
while we had no particular problems in the anastomoses. In these conditions,
minimizing the aortic dissection is mandatory; lateral dissection poses
a risk of caval or ureteral injuries and it is advisable to obtain a good
view of only the neck and the anterior wall of the aneurysm.
The prognosis of luetic aneurysms of the abdominal aorta is unknown,
also because this condition has been described as anecdotal. However,
the prognosis is poor considering that patients with luetic aneurysms
of the thoracic aorta, if not treated, show a mean life-expectancy of
6-9 months from the onset of symptoms and an 80% mortality within 2 years,
usually due to aortic dissection [7]. Surgery is the primary therapy and
must be associated with antibiotics (penicillin or erythromycin) for at
least 3 weeks.
The introduction of penicillin therapy in the 40's undoubtedly produced
a sharp reduction in the absolute incidence and mortality rates of tertiary
syphilis. However, an inadequate or interrupted antibiotic therapy may
hide primary and secondary symptoms that are fundamental for early diagnosis,
so making it difficult to recognize a cardiovascular lues [20]. When the
typical appearance of an inflammatory aneurysm is found at CT scan, a
syphilitic etiology cannot be excluded even if the patient history is
negative or classic symptoms of tertiary lues are missing. Moreover, a
significant increase in the incidence rates of syphilis has been reported
in USA [7] as in Eastern Europe [21]; this finding is part of an overall
increase of sexually transmitted diseases due to more heterogeneous sexual
habits but also to the significant incidence of drug addiction, AIDS and
venereal diseases among people involved in the "east-to-west" prostitution
traffic [21]. Also these epidemiological data suggest that, when faced
with an AAA apparently of "inflammatory" type, luetic etiology should
be considered in differential diagnosis.
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