Behcet disease
Summary
Behçet disease is a systemic vasculitis of unknown etiology characterized by the classic triad of recurrent oral aphthous ulcers, genital ulcers, and uveitis. It is associated with HLA-B51 and is most common in populations along the ancient 'Silk Road' (Turkey, Middle East, East Asia). Pathergy test positivity (skin hypersensitivity to needle prick) is a hallmark diagnostic clue.
Detail
Behçet disease is a rare, chronic, relapsing systemic vasculitis that can affect vessels of all sizes (arteries and veins), distinguishing it from most other vasculitides that typically affect a specific vessel size. The exact etiology is unknown, but it is thought to involve an autoimmune/autoinflammatory response triggered by environmental factors (possibly infectious) in genetically predisposed individuals, particularly those with HLA-B51.
Clinical features: - Oral aphthous ulcers (painful, recurrent, often the first manifestation) - Genital ulcers (painful, can scar) - Ocular involvement: uveitis (anterior or posterior), retinal vasculitis, which can lead to blindness if untreated - Skin lesions: erythema nodosum-like lesions, pseudofolliculitis, acneiform lesions - Pathergy phenomenon: sterile pustule formation at needle-prick sites within 24-48 hours (highly suggestive but not always present) - Vascular involvement: both arterial and venous thrombosis, including deep vein thrombosis, pulmonary artery aneurysms (can be life-threatening if ruptured) - Neuro-Behçet: CNS involvement causing headache, meningoencephalitis, stroke-like symptoms - GI involvement: ulcers mimicking inflammatory bowel disease - Arthritis: non-erosive, affecting large joints
Diagnosis is clinical, based on International Study Group criteria: recurrent oral ulceration plus two of the following: recurrent genital ulceration, eye lesions, skin lesions, or positive pathergy test. There is no specific lab test; ESR/CRP may be elevated but nonspecific.
Epidemiology: More common in males in Middle Eastern/Asian populations, though can occur in females as well, with disease severity often greater in young males. Peak onset is in the 20s-30s.
Management: Treatment depends on the organ system involved and severity. Colchicine is often used for mucocutaneous and joint symptoms. Topical or systemic corticosteroids are used for oral/genital ulcers and uveitis. Immunosuppressants (azathioprine, cyclosporine) or biologics (anti-TNF agents like infliximab) are used for severe ocular, vascular, or neurological disease. Anticoagulation is used cautiously for vascular thrombosis (controversial due to risk of pulmonary artery aneurysm rupture).
Complications: Blindness (from uveitis), pulmonary artery aneurysm rupture (life-threatening hemorrhage), neurological deficits, bowel perforation.
High-yield board points: Associate HLA-B51, pathergy test, oral+genital ulcers+uveitis triad, and the concept that this is a vasculitis affecting vessels of ALL sizes (unique feature).
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- UpToDate: Behçet syndrome: Clinical manifestations and diagnosis
- Kasper DL et al. Harrison's Principles of Internal Medicine
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