Is Behçet's Disease a Form of Vasculitis?
Yes, Behçet's disease is definitively a systemic vasculitis that uniquely affects blood vessels of all sizes—both arteries and veins—distinguishing it from most other vasculitides. 1
Classification as Vasculitis
Behçet's disease is classified as a small vessel vasculitis that is strongly associated with the HLA-B51 allele, but it is one of only two vasculitides that may also involve veins in addition to arteries. 1 The 2012 Chapel Hill Consensus on vasculitis nomenclature recognizes Behçet's disease within its classification system, though it acknowledges difficulty in determining which vessel sizes are involved since the disease can affect vessels of any caliber. 1
Unique Vascular Characteristics
The hallmark feature that distinguishes Behçet's from other systemic vasculitides is its ability to affect both the arterial and venous systems across all vessel sizes:
- Venous involvement is the predominant vascular manifestation, occurring approximately 4.5 times more frequently than arterial disease 2
- Small vessel vasculitis forms the pathological basis for multiorgan involvement, including the characteristic oral ulcers, genital ulcers, and uveitis 3
- Large vessel involvement can affect the aorta and major branches, with histopathology showing lymphocytic infiltration mixed with histiocytes and eosinophils around vasa vasorum 1
Pathological Features
The histology demonstrates systemic vasculitis with significant neutrophil infiltration, endothelial cell swelling, and fibrinoid necrosis affecting both arteries and veins. 4 This inflammatory process begins in the adventitial layer with augmented cytokine and matrix metalloproteinase (MMP) production, causing granuloma formation that both shields the vessel from inciting antigens and causes vessel destruction. 1
Clinical Implications of Vascular Involvement
Vascular manifestations occur in approximately one-third to 40% of patients with Behçet's disease, with a definite male preponderance: 1, 5
- Venous thrombosis is most common, particularly deep vein thrombosis in lower extremities (69.4% of vascular events) 2
- Arterial involvement primarily affects pulmonary arteries (12.9%) and can lead to aneurysm formation, pseudoaneurysm, and rupture 1, 2
- Superficial thrombophlebitis, deep vein thrombosis in the vena cava, varices, and cerebral sinus thrombosis have all been reported 1
Important Clinical Pitfalls
A critical caveat: Anastomotic pseudoaneurysms occur frequently after surgical repair (12.9% within 18 months in one series), likely related to ongoing inflammatory changes at suture lines. 1 This underscores that Behçet's is an active inflammatory vasculitis requiring immunosuppressive therapy rather than just anticoagulation for thrombotic events.
The thrombotic events in Behçet's disease cannot be solely attributed to abnormalities in thrombotic factors—they result from the underlying vasculitic inflammatory process. 2 Therefore, immunosuppressive therapy represents the primary treatment approach, with the role of anticoagulation remaining contentious. 5
Diagnostic Considerations
When evaluating for vasculitis, Behçet's disease should be strongly considered when a young male patient presents with arterial or venous vascular events, especially if recurrent. 2 The disease requires clinical diagnosis based on recurrent oral aphthous ulcers plus at least two of: recurrent genital ulceration, uveitis/retinal vasculitis, specific skin lesions, or positive pathergy test. 6, 7
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