Calcium pyrophosphate crystal arthritis — SCE Rheumatology MCQ
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Correct answer: A — Calcium pyrophosphate crystal arthritis
Calcium pyrophosphate crystal arthritis is the single best answer because rhomboid positively birefringent crystals indicate acute CPP crystal arthritis. The stem is testing diagnostic synthesis, 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.
Reference: NICE NG219; BSR gout and hot swollen joint guidance; BNF