A 40-year-old man presents with a 2-week history of recurrent oral ulcers, genital ulcers, intermittent ahritic pain of the knees and abdominal pain. Physical examination reveals shallow ulcerations of the mucosa of the glans penis, as well as oral aphthous ulcers and conjunctivitis. Pathergy test is positive. Which of the following is the most likely diagnosis?

Behcet's syndrome is a systemic vasculitis characterized by oral aphthous ulcers, genital ulceration and ocular inflammation, with occasional involvement of the nervous, gastrointestinal, and cardiovascular systems. The mucocutaneous lesions show a nonspecific vasculitis of aerioles, capillaries and venules. The cause of the necrotizing inflammation of small blood vessels is not known, but an association with specific HLA subtypes suggests an immune basis. Herpes does not present with ahritis. Nonspecific skin inflammatory reactivity to scratch or intradermal saline injection (pathergy test) is a specific manifestation.