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Dermatomyositis — SCE Rheumatology MCQ

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HardMyositisDermatomyositisSCE Rheumatology

A 42-year-old woman with newly diagnosed dermatomyositis has ulcerative Gottron papules, palmar papules, inflammatory arthritis, minimal muscle weakness and a normal creatine kinase concentration. She is positive for anti-MDA5 and anti-Ro52 antibodies and has not yet received immunosuppression. Over 10 days, she develops rapidly worsening dry cough, dyspnoea and hypoxaemia. HRCT shows extensive bilateral peripheral ground-glass opacification with patchy consolidation. Respiratory microbiological investigations are negative, and CT pulmonary angiography shows no embolus. Which complication is most strongly associated with early mortality in this clinical phenotype?

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Correct answer: E — Rapidly progressive interstitial lung disease

The correct answer is E. Anti-MDA5 dermatomyositis, often with little muscle disease but characteristic ulcerative or palmar skin lesions, has a strong association with rapidly progressive interstitial lung disease (RP-ILD). Rapid respiratory deterioration, hypoxaemia and extensive ground-glass or consolidative HRCT abnormalities identify the phenotype responsible for its marked early mortality. Anti-Ro52 co-positivity further supports a high-risk pulmonary phenotype. Pulmonary arterial hypertension is not the characteristic acute prognostic complication. Pulmonary embolism has been excluded by angiography. Malignancy risk is more strongly associated with other dermatomyositis autoantibody phenotypes, particularly anti-TIF1γ, and does not explain the acute lung presentation. Pneumocystis pneumonia is unlikely before immunosuppression and with negative microbiological investigations.

Reference: Sehgal S et al. Idiopathic inflammatory myopathies related lung disease in adults. Lancet Respiratory Medicine. 2025;13:272-288. https://pubmed.ncbi.nlm.nih.gov/39622261/