Behçet disease is a form of vasculitis that can lead to ulceration and other lesions. It can be interpreted as a chronic disturbance in the body s immune system. This system, which normally protects the body against infections through controlled inflammation, becomes overactive and produces unpredictable outbreaks of exaggerated inflammation. This extra inflammation affects blood vessels, usually the small ones. As a result, symptoms occur wherever there is a patch of inflammation, and can be anywhere where there is a blood supply. It is a diagnosis of exclusion, not a condition with a well defined etiology