The term sternocostoclavicular hyperostosis groups affections of different pathogenicity. These result from an ossifying enthesiopathy, either inflammatory, isolated to the thoracic wall anteriorly or combined with a spondylarthropathy, particularly ankylosing spondylitis, or degenerative, the anterior thoracic hyperostosis usually being part of an ensheathing vertebral hyperostosis. A differential diagnosis is anterior thoracic hyperostosis due to an inflammatory osteopathy occurring in young patients and often associated with other bone lesions of pelvis and spine or long bones.