Imaging Findings Suggestive of Axial Spondyloarthritis in Diffuse Idiopathic Skeletal Hyperostosis.

Objective: To describe the magnetic resonance imaging (MRI) findings in diffuse idiopathic skeletal hyperostosis (DISH) patients and to assess the proportion of DISH patients whose MRI findings would fulfill the Assessment of Spondyloarthritis International Society (ASAS) criteria for a positive MRI of axial spondyloarthritis (SpA).

Methods: This study involved all DISH patients who had a spine or sacroiliac (SI) joint MRI performed between January 2009 and December 2014. Sociodemographic and clinical data were collected. Available radiographs and MRI were analyzed and blindly scored by an experienced reader, using the Spondyloarthritis Research Consortium of Canada (SPARCC) scores for both spine and SI joint MRI.

Results: A total of 53 symptomatic DISH patients was included in the analysis. The mean ± SD SPARCC score of the spine was 18.3 ± 23.4. Thirty-five patients (67.3%) had at least 1 fatty corner. Thirty patients (57.7%) met the ASAS definition of a spine MRI suggestive of axial SpA, but only 6 patients (15.8%) with an available SI joint MRI had sacroiliitis according to ASAS criteria. Only 1 patient (3.3%) had ≥3 erosions on the SI joint.

Conclusion: Inflammatory lesions of the spine are common on the MRI of symptomatic DISH patients, and more than half fulfilled the ASAS criteria for a spine MRI suggestive of axial SpA. However, only a few patients met the ASAS definition of active sacroiliitis, suggesting that MRI of the SI joint but not of the spine might allow the differential diagnosis of DISH versus axial SpA in the elderly.