http://www.behcets.com/site/pp.asp?c=bhJIJSOCJrH&b=262325
American Behcet's Disease Association
This fact sheet discusses diagnosing Behçet's disease, which is very difficult because no specific test confirms it. Consequently, the diagnosis is based on the occurrence of symptoms and signs that are compatible with the disease, the presence of certain features that are particularly characteristic (e.g., oral or genital ulcerations), elimination of other possible causes of the patient’s presentation, and - whenever possible - proof of vasculitis by biopsy of an involved organ.