Diffuse idiopathic skeletal hyperostosis may give the typical postural abnormalities of advanced ankylosing spondylitis

OBJECTIVES: To describe a case-series of patients who presented with the typical postural abnormalities of long-standing advanced ankylosing spondylitis (AS) but were instead found to suffer from diffuse idiopathic skeletal hyperostosis (DISH). METHODS: We enrolled consecutive patients who showed postural abnormalities, which at first suggested to us the diagnosis of long-standing advanced AS, although the diagnostic process led us to the correct diagnosis of DISH. Each patient had a complete physical examination and radiographs of the spine and pelvis, and was investigated for HLA-B27 locus typing. RESULTS: From 15 June 1998 to 15 June 2006, 15 patients with DISH were seen who presented with the typical postural abnormalities of long-standing advanced AS. All patients were males with a median age of 69 yrs (range 51-91). All lacked HLA-B27 and denied personal or family history of spondyloarthritis. All measurements assessing cervical, thoracic and lumbar spinal movement were abnormal. CONCLUSIONS: Patients suffering from DISH can occasionally have severe limitations of spinal mobility, along with postural abnormalities that resemble long-standing advanced AS. Thus, the differential diagnosis between DISH and advanced AS is not limited to the radiological findings and can also extend to the clinical findings in the two diseases, as is highlighted by our report.