What are the clinical presentation and diagnostic criteria for Behcet's syndrome?

Clinical Presentation and Diagnosis of Behçet's Syndrome

Behçet's syndrome is diagnosed based on the presence of recurrent oral ulcers plus at least two of the following: genital ulcers, typical eye lesions (uveitis), characteristic skin lesions, or a positive pathergy test. 1

Cardinal Clinical Manifestations

Mucocutaneous Manifestations

• Oral ulcers:

  • Painful aphthous ulcerations
  • Recurrent (at least 3 times in 12 months)
  • May affect lips, tongue, gingiva, and buccal mucosa
  • Usually heal without scarring within 1-2 weeks

• Genital ulcers:

  • Similar in appearance to oral ulcers but often deeper
  • May heal with scarring
  • Common locations: scrotum, penis in males; vulva, vagina in females

• Skin lesions:

  • Erythema nodosum: painful, erythematous nodules typically on lower extremities
  • Papulopustular lesions: acne-like sterile pustules
  • Pathergy phenomenon: development of a papule or pustule 24-48 hours after skin puncture (diagnostic test)

Ocular Involvement

• Bilateral recurrent uveitis (anterior, posterior, or panuveitis)
• Retinal vasculitis
• Can lead to blindness if untreated
• More severe in males and younger patients

Vascular Involvement

• Affects approximately one-third of patients 1
• Can involve both arteries and veins of all sizes
• Venous thrombosis (superficial thrombophlebitis, deep vein thrombosis)
• Arterial aneurysms (especially pulmonary and aortic)
• Arterial occlusions

Neurological Involvement

• Parenchymal CNS lesions
• Cerebral venous thrombosis
• Headache, meningoencephalitis, focal neurological deficits

Gastrointestinal Involvement

• Ulcerations primarily in the ileocecal region
• Abdominal pain is the most common symptom 2
• Can lead to perforation or bleeding

Articular Involvement

• Non-erosive, non-deforming arthritis
• Usually affects knees, ankles, wrists, and elbows

Diagnostic Criteria

The International Study Group (ISG) criteria (1990) are most widely used for diagnosis 3:

• Required: Recurrent oral ulceration (at least 3 times in 12 months)
• Plus at least 2 of:
  1. Recurrent genital ulceration
  2. Eye lesions (uveitis or retinal vasculitis)
  3. Skin lesions (erythema nodosum, pseudofolliculitis, papulopustular lesions)
  4. Positive pathergy test

The International Criteria for Behçet's Disease (ICBD) was developed in 2014 to improve sensitivity 3:

• Point-based system:
  • Oral aphthosis: 2 points
  • Genital aphthosis: 2 points
  • Ocular manifestations: 2 points
  • Skin manifestations: 1 point
  • Neurological manifestations: 1 point
  • Vascular manifestations: 1 point
  • Positive pathergy test: 1 point
  • ≥4 points indicates Behçet's disease

Epidemiology and Risk Factors

• Highest prevalence along the ancient Silk Road (1-10 per 10,000 in Eastern Asia to Mediterranean)
• Much lower prevalence in Western countries (1-2 per 1,000 in UK and North America) 4
• Typical onset in third or fourth decade of life
• Equal male-to-female ratio overall, but more severe disease in males 1
• Strong association with HLA-B51 genotype 4

Disease Activity Assessment

The simplified Behçet's Disease Current Activity Form (2006 version) is recommended for evaluating disease activity, which is crucial for treatment selection and monitoring 3.

Differential Diagnosis

Important conditions to exclude:

• Sweet's disease
• Pemphigus
• Erythema nodosum from other causes
• Crohn's disease (especially for gastrointestinal manifestations)
• Recurrent aphthous stomatitis (without other manifestations)
• Other systemic vasculitides

Common Pitfalls in Diagnosis

1. Delayed diagnosis due to the episodic nature of symptoms and lack of specific laboratory tests
2. Overdiagnosis based solely on common symptoms like oral ulcers without meeting full criteria
3. Failure to recognize vascular complications which can be life-threatening
4. Missing neurological involvement which may present subtly but carries poor prognosis
5. Confusing with inflammatory bowel disease when gastrointestinal symptoms predominate

Key Laboratory and Imaging Findings

• No specific diagnostic laboratory test exists
• Nonspecific inflammatory markers may be elevated (ESR, CRP)
• Pathergy test (skin prick test) may be positive (more common in patients from endemic regions)
• CT scan may show bowel wall thickening in gastrointestinal involvement 2
• MRI for neurological manifestations
• Vascular imaging studies for suspected vascular involvement

Remember that Behçet's syndrome runs a chronic, unpredictable course with exacerbations and remissions that typically decrease in frequency and severity over time 2. Early recognition and appropriate treatment are essential to prevent irreversible organ damage, especially for ocular, vascular, neurological, and gastrointestinal manifestations which are associated with poor prognosis 1.