Behçet's disease (BD) is a chronic, relapsing, multisystemic vasculitis characterized by mucocutaneous lesions, as well as articular, vascular, ocular and central nervous system manifestations.
BD is most often reported in populations along the Silk Road, with highest prevalence reported in Turkey at >1/1,000, versus 1/10,000 in Japan. European cases are more often described in Mediterranean countries.
Onset most commonly occurs in adults, but pediatric cases have been reported. Relapsing episodes of round oral aphthae with sharp erythematous and elevated borders (1-3 cm diameter) may be accompanied by genital aphthae (>50%); cutaneous features may include pseudo-folliculitis and erythema nodosum. Ocular disorders (posterior uveitis (see this term), retinal vasculitis) occur in over 50% of BD patients. Arthralgia and/or arthritis are frequent (45%) and can occur as an initial symptom. Vasculitis (see this term) in BD is more frequent in the venous system where thromboses in femoro-iliac, superior and inferior vena cava and cerebral territories may occur. Rarer arterial thromboses and aneurysms primarily affect the pulmonary vessels. Sporadic neurological manifestations (neuro-BD) are frequent (>20%), often occuring 1-10 years after intial symptoms, and may include headache, pyramidal signs with hemiparesis, behavioral changes and sphincter dysfunction. Aphthoid and/or ulcerative lesions may affect the whole digestive tract but mainly the ileo-caecum and ascending colon, potentially leading to hemorrhages and perforations.
Of unknown origin, genetic predisposition in BD may allow certain infectious (in particular Streptococcus sanguis) and/or environmental insults to trigger symptoms involving sporadic inflammatory attacks reminiscent of auto-inflammatory disorders due to cross reactions with oral mucosa antigens. HLAB5101 antigen is associated to BD in 50-70% of patients and aberrant cytokine levels (eg- IL-6, TNF-a, IL-8, IL-12, IL-17 and IL-21) have been implicated in the pathogenesis of BD.
International classification criteria, as defined by clinical presentation, are sensitive and specific. The presence of recurrent oral aphtae, at least 3 times over 12 months, is mandatory, in combination with two of the following: recurrent genital ulceration, eye lesions, skin lesions or pathergy. In neuro-BD, lumbar puncture is mandatory and MRI may reveal inflammatory lesions in the cerebral trunk, brainstem and hemispheric areas.
Depending upon manifestations, infectious uveitis, relapsing polychondritis, sarcoidosis, antiphospholipid syndrome, Takayasu arteritis, Crohn disease or multiple sclerosis (see these terms) may be considered.
Anti-inflammatory steroids are the basis of treatment, however, corticodependance and relapses may occur upon discontinuation. Concurrent administration of immunosuppresive drugs (e.g. azathioprine, cyclophosphamide, methotrexate), are also prescribed but their action is delayed. Infliximab and alpha-interferon (2a or 2b) are efficient, particularly in severe uveitis, and antiagregant or anticoagulation treatments are used in the case of vascular involvement. Colchicine relieves mucocutaneous symptoms. Efficacy is dependent upon rapid initiation and patient compliance.
In the absence of treatment, the prognosis is severe due to ocular involvement leading potentially to blindness, the risk of lethal arterial rupture and neurological symptoms potentially causing encephalopathy that may lead to a loss of autonomy. Intensive ophthalmological care coupled with immunosuppressive treatment has been shown to reduce morbidity greatly..
- Dr David SAADOUN