A rare but important constellation of musculoskeletal and cutaneous symptoms, including synovitis, acne, pustulosis, hyperostosis, and osteitis, has recently been designated the SAPHO syndrome. The exact etiology is unknown, although various infectious agents have been proposed. The most common site of osteoarticular involvement is the sternoclavicular joint, and therefore, recognition of this syndrome and appropriate workup and management is crucial in the differential diagnosis of an anterior chest wall mass.