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Anti-MDA5 Dermatomyositis — RACP Adult Medicine MCQ

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HardRheumatologyAnti-MDA5 DermatomyositisRACP Adult Medicine

A 38-year-old woman presents with proximal muscle weakness, photosensitive rash over the upper chest (V-sign), and mechanic's hands (roughened, cracked skin on the lateral fingers). Anti-MDA5 antibodies are positive. CK is only mildly elevated. CT chest shows bilateral ground-glass opacification. What is the most serious complication she is at risk for?

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Correct answer: B — Rapidly progressive interstitial lung disease

Anti-MDA5 antibody-positive dermatomyositis is associated with rapidly progressive interstitial lung disease (RP-ILD), which carries a mortality rate of 50–80% without aggressive immunosuppression. The combination of V-sign rash, mechanic's hands, mild CK elevation (amyopathic or hypomyopathic dermatomyositis), and positive anti-MDA5 should prompt urgent ILD screening and aggressive treatment (typically triple immunosuppression with corticosteroids, calcineurin inhibitor, and cyclophosphamide).

Reference: eTG – 2025 – Rheumatology; ACR/EULAR – 2017 – Myositis Classification