To define the epidemiology and clinical features of Behçet's disease, giving special attention to unusual forms.
We retrospectively reviewed the medical records of 309 cases with joint manifestations among 450 cases of Behçet's disease seen over a 20-year period who met the International Study Group of Behçet's disease criteria.
Joint manifestations were present in 68.3% and were inaugural in 34.5%. The knee and ankles were the joints most commonly affected. Monoarthritis, oligoarthritis and polyarthritis were seen respectively in 12, 13.5 and 19.8%. Sacroiliitis is observed in 6%. Unusual forms included destructive polyarthritis (two cases), popliteal cyst (two cases), myositis (two cases) and ankylosing spondylitis (two cases).
Joint manifestations are common in Behçet's disease. They are frequently associated with erythema nodosum and necrotic pseudofolliculitis. Polyarthritis is not rare. Their unusual forms deserve to be known.