Drug-Induced Lupus — SCE Rheumatology MCQ

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ModerateSLE & Antiphospholipid SyndromeDrug-Induced LupusSCE Rheumatology

A 46-year-old woman with resistant hypertension develops fatigue, symmetrical small-joint polyarthritis and pleuritic chest pain after taking hydralazine for 10 months. ANA is positive with a homogeneous pattern and anti-histone antibodies are present. Anti-dsDNA antibodies are negative, complement concentrations are normal and urinalysis shows neither blood nor protein. What is the most likely diagnosis?

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Correct answer: D — Drug-induced lupus

The diagnosis is drug-induced lupus due to hydralazine. The discriminating features are onset after prolonged exposure to a recognised culprit drug, symmetrical polyarthritis and pleurisy, together with homogeneous ANA and anti-histone antibodies. Negative anti-dsDNA, normal complement and absence of haematuria or proteinuria support classic drug-induced lupus rather than idiopathic SLE, although no individual antibody is diagnostic in isolation. SLE remains the principal differential but is less likely given the medication relationship and lack of renal or complement abnormalities. Reactive arthritis usually follows gastrointestinal or genitourinary infection and is typically asymmetric; viral arthritis lacks this drug association and serological pattern. Adult-onset Still disease is usually ANA-negative and characterised by quotidian fever and marked hyperferritinaemia. Hydralazine should be withdrawn.

Reference: Hydralazine 25 mg Film-coated Tablets, Summary of Product Characteristics, section 4.4 Special warnings and precautions for use, current eMC SmPC, 2026. https://www.medicines.org.uk/emc/product/2604/smpc