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Behcet disease

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aliasesBehcet syndrome, Behçet syndrome, Behçet disease

3 min read

Epidemiology

  • Most commonly affects individuals from the Mediterranean region to eastern Asia, with the highest prevalence observed in Turkey and Japan

Etiology

  • Possible autoimmune and infectious triggers (e.g., precipitating HSV or parvovirus infection)
  • Strong HLA-B51 association

Pathophysiology

  • Autoimmune systemic vasculitis that can involve arteries and veins of all sizes
  • Characterized by the deposition of immune complexes, proliferation of CD4+ T cells, and increased cytokines

Clinical features

  • Presents in young adults (20s-40s).
  • Classic triad: c
    1. Recurrent, painful oral aphthous ulcers (required for Dx).
    2. Recurrent, painful genital ulcers.
    3. Uveitis (anterior or posterior) or retinal vasculitis. Can lead to hypopyon.
  • Skin Lesions:
    • Erythema nodosum-like lesions (often on shins). c
    • Papulopustular or acneiform lesions.
  • Arthritis: Non-erosive, migratory, oligoarticular arthritis, most often affecting knees and ankles.
  • Vascular Manifestations:
    • Thrombosis is common (DVT, cerebral venous sinus thrombosis, Budd-Chiari syndrome).
    • Aneurysms (especially pulmonary artery).
  • Neurologic Manifestations (“Neuro-Behçet’s”):
    • Aseptic meningitis or meningoencephalitis.
    • Brainstem syndromes, cranial nerve palsies.

Mnemonic

PATHERGY: Positive pathergy test, Aphthous oral ulcers, Thrombosis (arterial and venous), Hemoptysis (pulmonary artery aneurysm), Eye lesions (uveitis, retinal vasculitis), Recurrent Genital ulcers, Young at presentation (3rd decade)

Diagnostics

  • Approach: Primarily a clinical diagnosis; no pathognomonic laboratory test.
  • Diagnostic Criteria: Recurrent oral ulcerations (≥3 times in a 12-month period) plus at least 2 of the following:
    • Recurrent genital aphthae.
    • Characteristic eye lesions (anterior/posterior uveitis, retinal vasculitis).
    • Characteristic skin lesions (erythema nodosum, pseudofolliculitis).
    • Positive Pathergy test.
  • Initial/Bedside Evaluation:
    • Pathergy Test: Formation of a sterile erythematous papule or pustule (≥2 mm) 24–48 hours after oblique needle prick (20-G needle) into the skin. High specificity, variable sensitivity.
  • Key Labs:
    • ESR and CRP: Elevated during active disease (nonspecific).
    • HLA-B51 typing: Supportive (positive in up to 60–80% of endemic cases), but not diagnostic alone.
    • Autoantibody serologies (ANA, ANCA, RF): Typically negative.
  • Imaging:
    • CT Angiography / MRA: Indicated if vascular involvement is suspected; evaluates for pulmonary artery aneurysms or large-vessel thrombosis.
    • Brain MRI / MRV: Indicated for CNS symptoms to rule out parenchymal lesions or cerebral venous thrombosis.
  • Biopsy:
    • Rarely required; demonstrates leukocytoclastic vasculitis or non-specific neutrophilic vascular infiltration without granulomas.

Differential Diagnostics

  • Recurrent Aphthous Stomatitis (Canker Sores):
    • Diff by absence of genital ulcers, uveitis, cutaneous lesions, or systemic vasculitis.
  • Herpes Simplex Virus (HSV):
    • Diff by initial vesicular stage that ruptures into ulcers, positive viral PCR/Tzanck smear, and absence of systemic multi-organ vasculitis.
  • Systemic Lupus Erythematosus (SLE):
    • Diff by painless oral ulcers, malar rash, positive ANA, anti-dsDNA, anti-Smith, and cytopenias.
  • Reactive Arthritis:
    • Diff by asymmetric peripheral arthritis, urethritis/cervicitis, conjunctivitis, keratoderma blennorrhagica, and association with HLA-B27 rather than HLA-B51.
  • Crohn Disease:
    • Diff by prominent GI signs (chronic diarrhea, hematochezia, fistula/fissure formation), transmural skip lesions on colonoscopy, and absence of pathergy.

Treatment

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