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Axial spondyloarthritis — SCE Rheumatology MCQ

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EasySpondyloarthropathiesAxial spondyloarthritisSCE Rheumatology

A 28-year-old man has had low back pain for 9 months. The pain wakes him during the second half of the night, improves with exercise and is associated with alternating buttock pain. Examination shows reduced lumbar flexion and Achilles enthesitis. CRP is raised and he is HLA-B27 positive. Plain radiographs of the sacroiliac joints do not show sacroiliitis meeting modified New York criteria. MRI demonstrates sacroiliac bone marrow oedema meeting ASAS/OMERACT criteria. What is the most likely diagnosis?

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Correct answer: D — Non-radiographic axial spondyloarthritis

The diagnosis is non-radiographic axial spondyloarthritis. He has characteristic inflammatory axial symptoms, Achilles enthesitis, raised CRP and HLA-B27 positivity. The sacroiliac radiographs do not meet modified New York criteria, excluding the radiographic axial spondyloarthritis category, while MRI shows active sacroiliitis meeting ASAS/OMERACT criteria. Mechanical back pain would not explain the inflammatory pattern, objective inflammation and enthesitis. Axial psoriatic arthritis is less likely without psoriasis or related features. Infectious sacroiliitis is usually a more acute, often unilateral illness and does not account for this typical chronic spondyloarthritis phenotype.

Reference: National Institute for Health and Care Excellence. Spondyloarthritis in over 16s: diagnosis and management (NG65), recommendations 1.2.4–1.2.9. 2017; last reviewed 4 March 2025. https://www.nice.org.uk/guidance/ng65/chapter/Recommendations