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Reactive Arthritis — RACP Adult Medicine MCQ

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EasyRheumatologyReactive ArthritisRACP Adult Medicine

A 28-year-old man presents with asymmetric oligoarthritis (knee and ankle), conjunctivitis, and circinate balanitis 3 weeks after a chlamydial urethritis. HLA-B27 is positive. What is the most likely diagnosis?

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Correct answer: C — Reactive arthritis

Asymmetric oligoarthritis developing 1–4 weeks after genitourinary infection (Chlamydia trachomatis) with conjunctivitis and circinate balanitis is reactive arthritis (formerly Reiter syndrome). HLA-B27 is positive in ~75% of cases. Treatment is NSAIDs for arthritis and appropriate antibiotic for the underlying STI. Most cases are self-limiting within 3–12 months.

Reference: eTG Rheumatology – 2024 – Reactive Arthritis