Characteristics of Inflammatory Aortic Aneurysms
Inflammatory aortic aneurysms may present with abdominal pain in the absence of rupture, which is a key distinguishing feature from non-inflammatory aneurysms.
Definition and Pathophysiology
Inflammatory abdominal aortic aneurysms (IAAAs) are a distinct variant of aortic aneurysms characterized by:
- Extensive periaortic fibrosis and inflammation
- Thickened aortic walls
- Dense adhesions to surrounding structures
- Representing 3-10% of all abdominal aortic aneurysms 1
Key Clinical Characteristics
Presentation
- Patients are typically younger than those with atherosclerotic AAAs 2
- Usually symptomatic (unlike standard AAAs which are often asymptomatic until rupture)
- Abdominal or back pain is common even without rupture 2
- Weight loss may occur
- Elevated inflammatory markers (ESR, CRP) in most cases 2
Imaging Features
- "Mantle sign" on CT - circumferential thickening of the aortic wall with periaortic fibrosis 3
- Less likely to show intimal calcifications compared to atherosclerotic aneurysms 4
- Mural thrombosis is less common than in atherosclerotic aneurysms 4
- Periaortic soft tissue stranding and inflammatory response are common findings 4
Risk Factors
- Male sex (stronger association than with atherosclerotic AAAs)
- Smoking (stronger association than with atherosclerotic AAAs) 2
- Hypertension
- Hypercholesterolemia
Comparison with Non-inflammatory Aneurysms
| Feature | Inflammatory AAA | Non-inflammatory AAA |
|---|---|---|
| Pain | Common without rupture | Usually asymptomatic until rupture |
| Inflammatory markers | Elevated | Normal |
| Wall thickness | Thickened | Normal |
| Periaortic fibrosis | Present | Absent |
| Adhesions | Dense to surrounding structures | Minimal |
| Rupture risk | Lower than non-inflammatory [2] | Higher |
| Graft infection risk | Not increased | Baseline risk |
Management Considerations
Medical Management
- Smoking cessation is the first step of medical therapy 2
- Corticosteroids or immunomodulatory therapies are recommended as initial standard therapy 4, 5
- High-dose glucocorticoids with prolonged taper over 1-2 years 5
Surgical Management
- Surgical intervention is recommended when diameter exceeds 5.5 cm 2
- Higher technical difficulty due to inflammatory adhesions
- Experts suggest treating to clinical remission before elective repair whenever possible 4
- Endovascular repair (EVAR) is associated with:
Follow-up
- Closer monitoring after repair is necessary to track the inflammatory process
- Monitoring of renal function and ESR every 3-6 months for 24 months post-repair is reasonable 1
Conclusion
When evaluating the characteristics of inflammatory aortic aneurysms, the presence of abdominal pain without rupture is a key distinguishing feature. While these aneurysms have a lower rupture risk than non-inflammatory variants, they present unique management challenges due to periaortic fibrosis and adhesions. The inflammatory process requires specific medical management alongside surgical considerations.