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Difficulty: MediumRheumatology and Immunology

A 65-year-old man with a history of ischemic heart disease, hypertension, and recurrent ventricular arrhythmias comes to the clinic reporting progressive fatigue, muscle aches, and joint pain for the past 4 weeks. He was hospitalized 5 months ago for sustained ventricular tachycardia and was discharged on a new oral medication. His temperature is 37.8°C (100.0°F). Physical examination shows symmetrical swelling and tenderness in the metacarpophalangeal and proximal interphalangeal joints of both hands. There is a mild erythematous rash over his cheeks and the bridge of his nose. Laboratory studies show a normal complete blood count and normal renal function. Antinuclear antibody (ANA) and anti-histone antibodies are positive. Anti-double-stranded DNA (anti-dsDNA) antibodies are negative. Which of the following is the most appropriate next step in the management of this patient?

  1. Discontinue the current antiarrhythmic medication and observeAnswer
  2. B
    Administer intravenous furosemide and obtain an echocardiogram
  3. C
    Initiate empiric broad-spectrum intravenous antibiotics
  4. D
    Prescribe high-dose systemic corticosteroids and administer the live-attenuated zoster vaccine
  5. E
    Order a comprehensive paraneoplastic autoantibody panel

Answer

Discontinue the current antiarrhythmic medication and observe.
The patient's clinical presentation of fever, symmetric polyarthritis, and a malar rash following the initiation of an antiarrhythmic medication (most likely procainamide) is highly characteristic of Drug-Induced Lupus Erythematosus (DILE). This diagnosis is strongly supported by the serologic profile: a positive antinuclear antibody (ANA) and uniformly positive anti-histone antibodies, alongside negative anti-dsDNA antibodies and a lack of severe internal organ involvement (e.g., normal renal function). The most critical and effective initial management for DILE is the prompt discontinuation of the offending medication. Symptoms typically self-resolve within several weeks to months following drug cessation.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and timeline.
The patient developed constitutional symptoms, a malar rash, and symmetric polyarthritis a few months after starting a new medication for ventricular arrhythmias.
Establishing the temporal relationship between a new drug and the onset of autoimmune symptoms is the first step in suspecting a drug-induced etiology.
2
Evaluate the laboratory and serologic findings.
The patient has a positive ANA and positive anti-histone antibodies, but negative anti-dsDNA and no signs of end-organ renal damage.
Uniformly positive anti-histone antibodies combined with absent anti-dsDNA antibodies strongly differentiate Drug-Induced Lupus Erythematosus (DILE) from idiopathic Systemic Lupus Erythematosus (SLE).
3
Determine the appropriate intervention for the established diagnosis.
The most appropriate next step is to discontinue the offending medication (likely procainamide).
DILE is generally a reversible condition that resolves within weeks to months after the causative agent is removed, making drug cessation the definitive initial management.

Key Concept

Diagnosis and management of Drug-Induced Lupus Erythematosus (DILE).
Estimated Time:1m 30s
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Topics

Rheumatology and Immunology

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