Simultaneous occurrence of diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis in the same patient.

Diffuse idiopathic skeletal hyperostosis (DISH) frequently gives rise to some diagnostic confusion, as it may radiologically mimic ankylosing spondylitis (AS). A patient with features of DISH and AS is described and the literature is reviewed. The diagnostic value of sacroiliac computerized tomography is emphasized. The role of spinal mobility in the appearance of the enthesiophytes is discussed since our patient, who underwent a segmental fusion, presented different radiological features in the mobile segment and the fused region.