Magnetic resonance imaging of sternoclavicular joint arthritis due to SAPHO syndrome

A 55-year-old male had been experiencing pain over the left shoulder to the anterior part of the chest since two days. Physical examination indicated a body temperature of 37.8°C, as well as swelling, elevated temperature, and tenderness on the left side of the sternum (Figure 1). The pain worsened with elevation of the left shoulder, right rotation and retroflexion of the neck, and deep inspiration. Blood tests showed an inflammatory response (C-reactive protein, 13.1 mg/dL, erythrocyte sedimentation rate, 48 mm/h). Rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibody were negative. Joint aspiration was not performed because ultrasonography did not detect the effusion of sternoclavicular joints. Computed tomography (CT) scan of the sternoclavicular joints revealed an erosive change in the left sternoclavicular joint. Magnetic resonance with the short-T1 inversion-recovery (MR-STIR) sequence showed an abnormal signal in the left sternoclavicular joint (Figure 2). A non-steroidal anti-inflammatory drug was orally administered, and the symptoms disappeared after one month. Although no skin eruption developed during the follow-up, sternoclavicular joint arthritis due to SAPHO syndrome was diagnosed.