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Psoriasis — SCE Dermatology MCQ

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HardDermatopharmacologyPsoriasisSCE Dermatology

A 45-year-old woman presents with a chronic non-healing perianal ulcer. She has a 15-year history of plaque psoriasis. Biopsy shows granulomatous inflammation. She is being treated with Infliximab. Quantiferon gold test is positive. Chest X-ray is normal. What is the most important next step?

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Correct answer: B — Start prophylactic Isoniazid and continue Infliximab after 2 months of TB prophylaxis

Development of positive IGRA (Quantiferon) during biologic treatment indicates potential TB exposure. With a normal chest X-ray suggesting latent (not active) TB, the recommended approach per BAD/NICE guidelines is to start latent TB prophylaxis (Isoniazid ± Rifampicin) and withhold the biologic. After 2 months of adequate TB prophylaxis, the biologic may be carefully restarted with ongoing TB treatment completion. Quantiferon (IGRA) is NOT affected by prior BCG vaccination (unlike the Mantoux test), so this result should not be attributed to BCG. Sputum AFB should still be sent but treatment should not be delayed.

Reference: BAD 2020 Biologic Guidelines; NICE NG33 TB Guidelines