BD is an autoimmune vasculitis seen most often in young adults of Mediterranean or Far East region. It was first described by a Turkish dermatologist, Hulusi Behcet, in 1937 [5
]. It is characterized with the triad of recurrent oral aphthous ulcers, genital lesions, and uveitis.
Arterial involvement is a rare but a serious complication of BD that leads to mortality and morbidity [2
]. Arterial involvement may be occlusive or aneurysmal in nature. Aneurysms usually involve medium and large-sized arteries such as thoracic aorta, abdominal aorta, pulmonary, carotid, subclavian, and femoral arteries [6
]. Aneurysmal degeneration is thought to occur because of obliterative endarteritis of the vasa vasorum of the associated artery [6
]. Obliterative endarteritis of the vasa vasorum causes destruction of the medial layer and fibrosis. These arterial wall changes may lead to formation of a true aneurysm or produce a pseudoaneurysm due to arterial wall perforation [6
]. Rupture of the pseudoaneurysms located at areas that are difficult to access and that can bleed into body cavities, like the aorta, pulmonary, and subclavian arteries, is the major causes of mortality [11
The formation of an ACF between the abdominal aorta and the inferior vena cava is rare but a fatal complication of AAAs that is observed in less than 1% of all AAAs and 3-4% of ruptured AAAs [13
]. In most of the cases, the rupture is spontaneous and fistulizing AAAs is atherosclerotic but rarely has been reported to be in association with mycotic, sphylitic, and other aneurysm forming diseases such as Ehlers-Dunlos syndrome, Marfan's syndrome, and Takayasu arteritis. As far as our review there is no reported ACF due to pseudoaneurysm of the abdominal aorta associated with BD in the literature.
Preoperative diagnosis of ACF is sometimes difficult because the classical triad of abdominal pain and pulsatile abdominal mass with machinery-like bruit and high-output cardiac failure are present only in 20%–50% of all cases [14
]. Possible reasons for not making a preoperative diagnosis are thought to be because of a shock that is obscuring symptoms when an emergent operation is needed and decreased shunt through ACF due to compression of the inferior vena cavae by a large aneurysm and partial occlusion of the ACF due to mural thrombus which leads to decreased shunt [15
]. We did not note abdominal bruit in our patient due to mural thrombus in the aneurysmal sac causing partial obstruction and partial compression of the inferior vena cavae.
A definitive preoperative diagnosis offers advantages in surgical management of ACF. Computerized tomography (CT) is the usual way of evaluating abdominal aortic aneurysm. Ultrasonographic scanning, Magnetic Resonance Imagination (MRI), and angiography are also used for diagnosis [15
]. In nearly half of the cases diagnosis is established during the surgical procedure [3
Surgical repair is required in case of an AAA and ACF. Challenging problem during surgery is the venous bleeding from the fistula. This may be managed by a simple maneuver; distal and proximal manual compression of the vena cavae or transfemoral insertion of an occluding balloon catheter. Surgical mortality of the repair of ACF ranges from 10% to 66% [3
]. Recently, endovascular treatment of AAAs has gained popularity with promising results especially in patients associated with BD [11
According to our knowledge, our case is the first abdominal aortic pseudoaneurysm associated with ACF in a BD patient in English literature.
As a conclusion, diagnosis of BD should always be considered in patients who present with aortic aneurysm or pseudoaneurysm especially in young adults from Mediterranean region or Asia. Additionally, ACF associating with AAA or pseudoaneurysm should be kept in mind as a complication. Patients with BD should also be under regular evaluation for diagnosis of arterial complications. Surgery or endovascular treatment modalities must be considered for any aneurysm or pseudoaneurysm complicating BD with a risk of rupture or ACF formation.