A 52-year-old woman on long-term procainamide for arrhythmia develops arthralgia, myalgia, low-grade fever, and pleuritis. ANA is positive at 1:320. Anti-histone antibodies are positive. Anti-dsDNA is negative. What is the most likely diagnosis?

• A Systemic lupus erythematosus
• B Undifferentiated connective tissue disease
• C Mixed connective tissue disease
• D Drug-induced lupus erythematosus ✓

Explanation

Drug-induced lupus is associated with procainamide, hydralazine, isoniazid, and minocycline, among others. It presents with arthralgia, myalgia, serositis, and positive ANA. Anti-histone antibodies are present in over 95% of drug-induced lupus cases, while anti-dsDNA is usually negative. Renal and CNS involvement is rare. Drug-induced lupus typically resolves after stopping the offending agent.

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

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Written and medically reviewed by the StethoPrep medical team.