Calcium pyrophosphate crystal arthritis — SCE Rheumatology MCQ

Correct answer: B — Use joint steroid injection after excluding infection by aspiration

The best answer is “Use joint steroid injection after excluding infection by aspiration”. Use intra-articular corticosteroid when infection is excluded and systemic drugs are risky is the single best answer because rhomboid positively birefringent crystals indicate acute CPP crystal arthritis. The stem is testing management choice, not isolated recall, so the relevant clinical pattern and risk context determine the answer. Septic arthritis is less suitable because it fits a different clinical pattern or a different treatment threshold; Reactive arthritis, Serum urate alone and Allopurinol during severe drug rash do not address the key discriminator in this vignette. Clinical pearl: in SCE-style rheumatology questions, autoantibodies, imaging and synovial fluid findings should be interpreted with the whole phenotype. The competing options represent related diagnoses, tests or treatments, but they do not match the decisive phenotype, safety constraint or management point in this stem.

Reference: EULAR CPPD management recommendations: https://ard.bmj.com/content/70/4/571