A patient presents with painful oral ulcerations, swollen and painful knees, and enlarged tender submandibular and cervical lymph nodes. Which condition BEST accounts for this combination?

Correct answer: C. Behçet's disease

• A. Pemphigus vulgaris causes flaccid bullae and painful erosions of oral mucosa and skin with a positive Nikolsky sign, but does not cause arthritis.
• B. Sjögren syndrome causes dry mouth and dry eyes from lymphocytic destruction of exocrine glands. It may accompany rheumatoid arthritis, but oral ULCERATION is not its hallmark — xerostomia is.
• C. CORRECT. BEHÇET'S DISEASE is a systemic vasculitis whose defining feature is RECURRENT ORAL ULCERATION (aphthous-like, at least three times yearly), accompanied by some combination of genital ulceration, uveitis and skin lesions. ARTHRITIS is a common systemic manifestation, typically a non-erosive oligoarthritis favoring the KNEES and ankles. The oral-plus-joint pattern described here fits Behçet's directly.
• D. Sickle cell anemia produces vaso-occlusive pain crises, and the jaws may show a stepladder trabecular pattern and mental nerve neuropathy — but recurrent oral ulceration with knee arthritis is not its presentation.

Note: Behçet's is most prevalent along the historic Silk Road (Turkey, Middle East, East Asia). The pathergy test — a sterile pustule forming at a needle-prick site — supports the diagnosis. Ophthalmology referral is urgent, since uveitis can blind.