A 52-year-old woman presents with 3 months of proximal muscle weakness (inability to rise from a chair), dysphagia, and Gottron's papules on her knuckles. Serum CK is 4800 U/L. Anti-MDA5 antibody is positive. CXR shows bilateral ground-glass opacities. The most feared complication of anti-MDA5-positive dermatomyositis is:

• A Cardiac arrhythmia from myocardial involvement
• B Renal crisis (similar to scleroderma renal crisis)
• C Rapidly progressive interstitial lung disease (RP-ILD) ✓
• D Malignancy (elevated paraneoplastic risk)

Explanation

Anti-MDA5 (anti-melanoma differentiation-associated gene 5) antibody defines a distinct dermatomyositis subset characterized by rapidly progressive ILD — the most feared and life-threatening complication, with mortality exceeding 30–50% if untreated. Paradoxically, anti-MDA5 patients may have minimal muscle weakness ('amyopathic dermatomyositis') but severe lung disease. Skin features include Gottron's papules, skin ulceration, and palmar papules. Malignancy risk is highest with anti-TIF1-gamma and anti-NXP2 antibodies, not anti-MDA5.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.