[Myositis of the sternocleidomastoid muscle as a result of arthritis of the sternoclavicular joint].

This article describes a rare case of a myositis of the sternocleidomastoid muscle due to an acute septic arthritis of the sternoclavicular joint. A 51-year-old male in reduced condition was admitted to the Department of Otorhinolaryngology with a one-week history of a painless swelling of the sternocleidomastoid muscle associated with recurrent fever. Physical examination was otherwise unremarkable. An intravenous antibiotic therapy was initiated without improvement of the process, accordingly a specific infection or a malignancy was ruled out by biopsy. The positron emission tomography and magnetic resonance imaging finally revealed the diagnosis of a septic arthritis of the sternoclavicular joint as the causal focus of the infection. After an extensive surgical debridement and under continued antibiotic therapy the patient made an uneventful recovery. The acute septic arthritis of the sternoclavicular joint is an uncommon infection with an insidious onset and is often unrecognized until it spreads to adjacent structures leading to serious complications. This case emphasizes that a myositis of sternocleidomastoid muscle can be caused by an ascending infection due to an acute septic arthritis of the sternoclavicular joint. Clinical course, diagnosis and treatment of this uncommon disease are reviewed in this article.