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Erosive OA vs PsA Imaging — SCE Rheumatology MCQ

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HardMusculoskeletal ImagingErosive OA vs PsA ImagingSCE Rheumatology

A 65-year-old woman has recurrent inflammatory flares affecting multiple distal and proximal interphalangeal joints. She has Heberden and Bouchard nodes, but no psoriasis, nail dystrophy or dactylitis. Her CRP is mildly elevated. Which radiographic pattern would most strongly favour erosive hand osteoarthritis rather than psoriatic arthritis?

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Correct answer: C — Central erosions with marginal osteophytes producing gull-wing remodelling at multiple distal and proximal interphalangeal joints, with metacarpophalangeal sparing

Explanation lettering: C = shown as A · D = shown as B · E = shown as C · A = shown as D · B = shown as E

E is correct. Erosive hand osteoarthritis typically affects multiple DIP and PIP joints and combines osteoarthritic features—joint-space loss, sclerosis and osteophytes—with central subchondral erosions. The residual marginal bone creates the characteristic gull-wing appearance; MCP joints are usually spared. A describes the marginal erosions, periosteal new bone formation and asymmetric ray distribution that favour psoriatic arthritis. B comprises advanced PsA features, although pencil-in-cup change is neither early nor universally present. C is more typical of rheumatoid arthritis, particularly because of MCP involvement and juxta-articular osteopenia. D suggests CPPD arthropathy. A mildly elevated CRP does not exclude erosive osteoarthritis, so the erosion location and overall distribution are more discriminating than the inflammatory marker alone.

Reference: Ezzati F, Pezeshk P. Radiographic Findings of Inflammatory Arthritis and Mimics in the Hands. Diagnostics. 2022;12:2134. https://pubmed.ncbi.nlm.nih.gov/36140535/