Background Diffuse idiopathic skeletal hyperostosis (DISH) is a non-inflammatory condition that involves calcification and ossification of the spinal ligaments and entheses. In axial spondyloarthritis (SpA), an inflammatory disease associated with spinal ankylosis and enthesopathies, the pattern of new bone formation seen in the spine is different. While, characteristic magnetic resonance imaging (MRI) lesions of the spine in patients with SpA have been extensively described and defined1, there is a paucity of information regarding the MRI findings in DISH.
Objectives To describe the MRI findings of patients with a radiographic diagnosis of DISH.
Methods We collected computed tomography studies with findings characteristic of DISH (according to the classification criteria set by Resnick and Niwayama2) and that also had corresponding and concurrent MRI studies of the spine. For each patient, sagittal T1 and STIR MRI sequences were evaluated for anterior/posterior spondylitis and marrow fat depositions at the vertebral corners.
Results Imaging studies of 10 patients had both radiographic evidence of DISH and available MRI studies of the spine. The male:female ratio was 4:1 and the median age was 70 years (range 64-82). The indications for imaging included back pain (n=4), trauma (n=2), suspected space occupying lesion (n=2), osteomyelitis (n=1) and atelectasis (n=1). Vertebral corner fat depositions were detected in 8 patients. In 3 of these patients, at least 3 vertebrae were involved, a finding suggestive of axial SpA according to the ASAS/OMERACT consensus statement2. Lesions consistent with anterior/posterior spondylitis at vertebral corners were detected in 3 patients, and in one patient lesions were detected in 3 separate vertebrae.
Conclusions In a cohort of patients with DISH, about a third display spinal MRI lesions that are characteristic of axial spondyloarthritis. This bears relevance to cases with diagnostic uncertainty and may imply overlapping pathogenetic mechanisms for new bone formation in both SpA and DISH. Further study is indicated to better characterize the similarities and differences between the MRI lesions of DISH and SpA.
Hermann KG, Baraliakos X, van der Heijde DM, et al. Descriptions of spinal MRI lesions and definition of a positive MRI of the spine in axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI study group. Ann Rheum Dis. 2012;71:1278-88.
Resnick D, Niwayama G. Radiographic and pathologic features of spinal involvement in diffuse idiopathic skeletal hyperostosis (DISH). Radiology. 1976;119:559-568.
Disclosure of Interest None Declared