Peripheral hyperostosis in rheumatoid arthritis in the absence of axial involvement

When diffuse idiopathic skeletal hyperostosis (DISH), or Forestier's disease, coexists with rheumatoid arthritis (RA), the radiographic features of RA are characteristically altered and may be diagnostically misleading. Altered findings include the absence of osteoporosis, bony proliferation around erosions, osteophytosis and ankylosis. Previously reported cases of coexistent RA-DISH have all exhibited characteristic spinal hyperostosis. Two cases are discussed which demonstrate that the distinctive peripheral radiographic findings of RA-DISH may occur in the absence of vertebral involvement.