Clinical features:
(1) often male
(2) most patients have a history of smoking
(3) patients tend to be younger than patients with atherosclerotic aneurysms (approximately 5-10 years younger)
(4) often present with back and/or abdominal pain
(5) may have systemic symptoms of fever, malaise and weight loss
(6) often have risk factors for atherosclerotic disease
(7) may have elevated ESR or C-reactive protein
(8) may have an autoimmune disease
(9) may present with duodenal or inferior vena caval obstruction if there is retroperitoneal fibrosis
(10) may have a pulsatile abdominal mass
(11) relatively low risk of rupture with hemorrhage
Pathologic features:
(1) marked thickening of the aneurysm wall, due to expansion of the adventitia caused by periaoritis and fibrosis
(2) dense fibrosis in adjacent retroperitoneum
(3) adhesions between adjacent structures and the anterior wall of the aneurysm
(4) absence of inflammation in other arteries (i.e., absence of vasculitis)
(5) inflammatory cell infiltrate consisting predominantly of lymphocytes, plasma cells and macrophages
Imaging findings:
(1) fusiform dilatation of the infrarenal abdominal aorta
(2) perianeurysmal fat stranding on CT or MRI
(3) extensive calcification of the aortic media
Differential diagnosis:
(1) atherosclerotic aortic aneurysm
(2) defect in connective tissue
(2a) Marfan's syndrome
(2b) Ehlers-Danlos syndrome
(2c) cystic medial necrosis
(3) infectious aortitis
(3a) Salmonellosis
(3b) syphilis
(4) vasculitis
(4a) Cogan syndrome (with vasculitis affecting the thoracic aorta)
(4b) Takayasu aortitis
(4c) temporal arteritis
(5) tumors
(5a) bladder cancer
(5b) liposarcoma
