What is Behcet syndrome?

What is Behçet Syndrome?

Behçet syndrome is a chronic systemic inflammatory vasculitis of unknown origin that affects blood vessels of all sizes (both arteries and veins) and is characterized by recurrent oral and genital ulcers, ocular inflammation, skin lesions, and potential involvement of vascular, neurological, and gastrointestinal systems. 1, 2, 3

Core Clinical Features

Mucocutaneous Manifestations:

• Recurrent oral aphthous ulcers are the hallmark feature, occurring in virtually all patients 4, 2
• Genital ulcers develop in the majority of patients and can cause permanent scarring if untreated, potentially leading to oropharyngeal narrowing and obliterative/deforming genital scarring 5, 6
• Skin lesions include erythema nodosum-like lesions (more diagnostically significant) and papulopustular or acne-like lesions 4
• These mucocutaneous features impair quality of life but do not cause permanent organ damage 1, 5

Major Organ Involvement (Poor Prognostic Features):

• Ocular: Posterior uveitis and retinal vasculitis are common and can lead to severe visual impairment or blindness if untreated 4, 7
• Vascular: Affects approximately one-third of patients, involving both venous thrombosis (especially deep vein and cerebral venous thrombosis) and arterial disease including aneurysms 4, 6
• Neurological: Occurs in 5-10% of cases, presenting as parenchymal brain involvement (typically subacute brainstem syndrome) or cerebral venous sinus thrombosis 8
• Gastrointestinal: Intestinal ulcers that can cause serious complications 1, 5

Epidemiology and Risk Factors

Geographic Distribution:

• Particularly prevalent along the ancient Silk Road, from the Mediterranean to the Far East 2, 9

Demographics:

• Disease onset typically occurs in the third or fourth decade of life (ages 20-40 years) 2, 7
• Sex ratio is roughly 1:1, though young males with early disease onset experience more severe disease courses requiring aggressive treatment and closer follow-up 5, 6, 2

Genetic Factors:

• HLA-B51 allele is the strongest genetic risk factor, with moderate positive predictive value (approximately 55%) and high negative predictive value (84-90%) 4, 9
• HLA-B51 testing should not be used as a standalone diagnostic test but rather as supportive evidence 4

Diagnostic Approach

Clinical Diagnostic Criteria:

• Diagnosis requires recurrent oral aphthous ulcers plus at least two of the following: recurrent genital ulceration, uveitis/retinal vasculitis, specific skin lesions (particularly erythema nodosum-like lesions), or positive pathergy test 4, 6
• No laboratory examination has diagnostic value; diagnosis is made based on clinical manifestations 2

Important Diagnostic Considerations:

• A thorough genital examination is necessary to search for genital ulcers or scars 4
• Complete ophthalmologic examination is mandatory to assess for uveitis or retinal vasculitis 4
• Inflammatory markers (ESR, CRP) can monitor disease activity but are not specific 4

Disease Course and Prognosis

Natural History:

• Behçet syndrome follows a chronic relapsing-remitting course with unpredictable exacerbations 1, 5
• Disease manifestations typically ameliorate over time in many patients, allowing for treatment tapering or discontinuation 1, 5
• Ocular, vascular, neurological, and gastrointestinal involvement are associated with poor prognosis and can cause serious damage or death if untreated 1, 5, 6

Treatment Implications:

• When only skin, mucosa, and joint involvement exists, treatment can be tailored according to quality of life impact versus medication risks 5
• When major organ involvement occurs, rapid suppression of inflammation with immunosuppressives is critical to prevent irreversible loss of function 1, 5