Behçet Disease (Adamantiades–Behçet Disease)

Definition & Overview

Behçet disease (BD) is a multisystem inflammatory disorder of unknown etiology, classified as a systemic vasculitis involving all types and sizes of blood vessels. It is characterized by recurrent oral aphthous ulcers, genital ulcers, skin lesions, uveitis, and arthritis, with variable involvement of vascular, GI, and neurologic systems. — Fitzpatrick's Dermatology, Ch. 141

Epidemiology

Prevalent along the "Silk Road" — highest rates in Turkey (80–420 per 100,000), followed by the Middle East and East Asia (Japan 14–31, Korea 35, Iran 17 per 100,000)
Rare in Northern Europe (0.27–1.18 per 100,000) and the USA (0.75 per 100,000)
Peak onset: 20s and 30s
Gender: largely equal overall, though male predominance persists in Arab populations; female predominance in Korea and USA

Pathogenesis

Genetically determined with probable environmental triggers
Strongly associated with HLA-B51 (especially in endemic regions)
Fundamental lesion: neutrophilic vascular reaction / vasculitis
Lymphocytic perivasculitis is also seen (often in older lesions)
Autoimmune dysregulation with T-cell and neutrophil hyperactivation

Clinical Features

1. Mucocutaneous (most common, usually first)

Feature	Details
Oral aphthous ulcers	Recurrent, painful; often the presenting sign; minor, major, or herpetiform types
Genital ulcers	Scrotum, penis, vulva, cervix; painful; often leave scars (unlike oral ulcers)
Papulopustular lesions	Acneiform; on face, neck, chest
Erythema nodosum–like lesions	Tender nodules, typically on legs
Pseudofolliculitis	Sterile pustules at hair follicles

2. Ocular

Uveitis (iridocyclitis / posterior uveitis) — may appear years after oral ulcers
Risk of blindness if untreated
Patients may initially report seeing spots

3. Neurological (~20%)

Aseptic meningitis / meningoencephalitis
Focal/multifocal neurological deficits — small vessel inflammatory disease; brainstem frequently involved
Cerebral venous sinus thrombosis
CSF: mild pleocytosis, elevated protein
Peripheral neuropathy (rare): polyneuropathy or mononeuropathy multiplex

4. Vascular

Venous thrombosis (DVT, Budd-Chiari)
Arterial aneurysms (pulmonary, aorta)
Pulmonary arterial aneurysm → arterio-bronchial fistula → massive hemoptysis
Post-anastomotic aneurysms (pathergy phenomenon)

5. Gastrointestinal

Abdominal pain, GI bleeding, perforation
Ileocecal ulcers most common (can mimic Crohn disease)

6. Articular

Non-destructive, asymmetric oligoarthritis of large joints (knees, ankles)

Clinical Images

Behçet Disease — oral aphthous ulcers (A), erythema nodosum-like nodules on leg (B), positive pathergy test (C)

Fig. A: Oral aphthous ulcers; B: Erythema nodosum-like leg nodules (arrows); C: Positive pathergy test at 36 h (circled)

Positive pathergy reaction — bilateral forearm crateriform ulcers after needle prick

Pathergy reaction: crateriform ulcers with central necrosis developing after needle prick — hallmark of neutrophilic hyperreactivity in BD

Diagnosis

International Criteria for Behçet Disease (ICBD Scoring System)

Feature	Points
Ocular lesions (recurrent)	2
Oral aphthosis (recurrent)	2
Genital aphthosis (recurrent)	2
Skin lesions (recurrent)	1
CNS involvement	1
Vascular manifestations	1
Positive pathergy test	1

Score ≥4 = Behçet Disease — Fitzpatrick's Dermatology, Table 141-1

Pathergy Test

Needle prick or 0.1 mL intradermal saline injection on volar forearm
Positive: erythematous papule/pustule >2 mm within 48 hours
Not pathognomonic — also seen in pyoderma gangrenosum, Crohn's, rheumatoid arthritis

Other Investigations

No specific serologic test; HLA-B51 supports diagnosis in appropriate context
Cranial MRI: hypodense/atrophic brain changes in neuro-Behçet
Angiography for vascular lesions
CSF analysis when CNS involvement suspected

Differential Diagnosis

Category	Conditions
Oculocutaneous/mucocutaneous	Stevens-Johnson syndrome, Reiter syndrome, Sweet syndrome, pemphigus
GI/systemic	Crohn disease (most important — also has aphthae, uveitis, skin lesions), ulcerative colitis
Infectious	HSV, syphilis, HIV
Other vasculitides	Systemic lupus, polyarteritis nodosa

Differentiating from Crohn disease is particularly challenging as both share aphthous ulceration, skin lesions, and uveitis.

Treatment

Manifestation	Treatment
Oral/genital ulcers	Topical corticosteroids, colchicine (first-line for mucocutaneous)
Skin lesions	Colchicine, dapsone
Uveitis / retinal disease	Systemic glucocorticoids + azathioprine; cyclosporine for refractory cases
CNS involvement	Systemic corticosteroids ± azathioprine; anticoagulation for cerebral venous thrombosis
Severe systemic disease	Azathioprine, cyclophosphamide, interferon-α, anti-TNF agents (infliximab, adalimumab)
Vascular disease	Immunosuppression + anticoagulation; surgical/endovascular for aneurysms

The primary goal in primary care is early recognition and prompt referral to ophthalmology to prevent irreversible visual loss. — Textbook of Family Medicine, 9e

Prognosis

Course: chronic, relapsing, progressive
Worse prognosis in: males, early-onset disease, HLA-B51 positivity, recurrent erythema nodosum, systemic presentations (vascular, CNS)
Mortality: 0–6% (mainly from vascular complications — pulmonary hemorrhage, CNS disease)
Mucocutaneous symptoms may improve with age; ocular disease most feared for permanent disability

Sources: Fitzpatrick's Dermatology (Ch. 141), Textbook of Family Medicine 9e, Bradley & Daroff's Neurology in Clinical Practice

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