LAUSR

OBJECTIVES Muscle involvement in Behçet's disease (BD) is rare, and several cases have been reported in the literature. Therefore, this study aimed to describe the clinical, laboratory, and imaging findings in adult patients presenting with BD-associated myositis before the diagnosis of BD. METHODS We retrospectively screened patients who visited a locomotive medicine clinic presenting with myalgia, local swelling, or tenderness of extremities without an established diagnosis of BD. We enrolled patients whose pain in the extremities was proven to be suggestive of focal vasculitic myositis and who were eventually diagnosed as having BD at the initial visit or during follow-up. We thoroughly reviewed the clinical, histological and imaging findings and treatment outcomes in patients who presented with focal vasculitic myositis as the primary manifestation of BD. RESULTS Ten adult patients with focal vasculitic myositis as the primary manifestation of BD were enrolled. The lower and upper extremities were affected in eight and two patients, respectively. The affected lower extremities were the calf (n = 6) and thigh muscles (n = 2). The common findings of magnetic resonance imaging included high signal intensity of the affected muscles and intermuscular fascia on fat-suppressed images, suggestive of myofascitis and edematous changes in the subcutaneous layer. The results of skin or muscle biopsy were suggestive of vasculitis. All the patients were pain-free at the short-term follow-up (1-3 weeks) after oral steroid therapy. CONCLUSION Focal vasculitic myositis can be a primary manifestation of BD warranting medical attention. BD-associated myositis responds well to oral steroid therapy.