Magnetic resonance imaging of sternoclavicular joint arthritis due to SAPHO syndrome

Abstract

Conditions of the sternoclavicular joints are sometimes misdiagnosed as shoulder diseases because sternoclavicular joints are involved during shoulder joint elevation. When inflammation related to sternoclavicular joint arthritis spreads to the sternocleidomastoid muscles, retroflexion of the neck or rotation to the unaffected side causes pain. Sternoclavicular joint arthritis may be caused by septic arthritis, osteoarthritis, rheumatoid arthritis, SAPHO syndrome, ankylosing spondylitis, psoriasis, gout, or pseudogout. Among those, erosive changes of in sternoclavicular joints have been observed in rheumatoid arthritis, ankylosing spondylitis, psoriasis and SAPHO syndrome. Anti-CCP antibody was negative in this patient, making rheumatoid arthritis unlikely. Ankylosing spondylitis typically develops in young adults and occurs insidiously. Nail lesions and dactylitis were not observed, making psoriatic arthritis unlikely. Among patients with SAPHO syndrome, 6590% experience damage in the bones and joints of the anterior chest. Skin symptoms such as severe acne and palmoplantar pustulosis aid the diagnosis of SAPHO syndrome. However, 3260% of patients develop bone and joint symptoms several years before skin symptoms, and 15% of patients do not develop skin symptoms. Osteolytic changes are often noted at an earlier stage with or without osteosclerotic findings [2]. A computed tomography scan reveals an erosive change in the bone, and MR-STIR imaging shows an abnormally high signal in the bone. MR-STIR imaging can help differentiate active lesions from chronic ones.