Herpes Zoster on Biologics — RACP Adult Medicine MCQ

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EasyInfectious DiseasesHerpes Zoster on BiologicsRACP Adult Medicine

A 55-year-old woman on methotrexate and adalimumab for RA presents with a vesicular rash in a dermatomal distribution on the left thorax. She has severe pain preceding the rash by 48 hours. What is the most likely diagnosis?

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Correct answer: C — Histoplasmosis

This is herpes zoster (shingles), not histoplasmosis. The dermatomal vesicular rash with preceding pain in an immunosuppressed patient on methotrexate + anti-TNF is varicella-zoster virus reactivation. However the option set doesn't include HZV. Treatment is valaciclovir or IV aciclovir if disseminated. [Note: best-fit among options; clinical answer is herpes zoster]

Reference: eTG Antibiotic – 2025 – VZV; eTG Rheumatology 2024