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Difficulty: HardRheumatology and Immunology

A 6464-year-old man comes to the clinic with a 33-week history of worsening joint pain, morning stiffness lasting over an hour, and low-grade fevers. He also reports sharp, left-sided chest pain that worsens with deep inspiration and coughing. His medical history includes heart failure with reduced ejection fraction, hypertension, and bipolar disorder. Five months ago, he was hospitalized for a heart failure exacerbation, and his medical regimen was adjusted. Current medications include carvedilol, spironolactone, hydralazine, isosorbide dinitrate, and lithium. Temperature is 37.8∘C37.8^\circ\text{C} (100.0∘F100.0^\circ\text{F}), blood pressure is 110/70 mmHg110/70\text{ mmHg}, and heart rate is 78/min78/\text{min}. Physical examination reveals a pleural friction rub at the left lung base. There is symmetric swelling, warmth, and tenderness of the proximal interphalangeal joints and wrists bilaterally. Laboratory testing shows normal C3 and C4 complement levels, and a positive antinuclear antibody (ANA) titer of 1:6401:640 with a homogeneous pattern. Anti-double-stranded DNA (anti-dsDNA) antibodies are negative. Which of the following is the most appropriate next step in management?

  1. A
    Initiate intravenous furosemide and noninvasive positive pressure ventilation
  2. B
    Order blood cultures and start empiric vancomycin and piperacillin-tazobactam
  3. C
    Reassure the patient that the antinuclear antibody result is a false positive and prescribe acetaminophen
  4. Discontinue hydralazine and monitor for symptom resolutionAnswer
  5. E
    Discontinue lithium and initiate monotherapy with citalopram

Answer

Discontinue hydralazine and monitor for symptom resolution.
The correct intervention is to discontinue hydralazine. This patient's acute presentation of fever, symmetric polyarthritis, and serositis (pleuritic chest pain with a friction rub), combined with a high-titer positive ANA and normal complement levels, is the classic presentation of drug-induced lupus erythematosus (DILE). Hydralazine, which he started 55 months ago for heart failure, is one of the highest-risk medications for triggering DILE. The cornerstone of management is identifying and stopping the offending drug, which usually leads to the resolution of symptoms without the need for long-term immunosuppression.

Step-by-Step Solution

1
Identify the primary clinical syndrome from the patient's presentation.
The patient has systemic inflammation (fever), serositis (pleuritic chest pain, friction rub), and symmetric polyarthritis (swollen PIPs/wrists).
Recognizing the triad of fever, joint pain, and serositis builds the foundation for an autoimmune or inflammatory differential diagnosis.
2
Synthesize the laboratory data with the clinical picture.
A highly positive ANA with normal C3/C4 complement levels and negative anti-dsDNA strongly suggests drug-induced lupus erythematosus (DILE) rather than idiopathic SLE (which typically features low complements during active flares).
Serologic markers and complement levels are key discriminators between idiopathic SLE and DILE.
3
Review the patient's medication list for known culprits.
The patient was started on hydralazine 55 months ago, which is a classic high-risk medication for DILE.
Identifying the temporal relationship between a new medication and symptom onset is required to confirm DILE.
4
Determine the appropriate management intervention.
The primary and most effective treatment is to discontinue the offending agent (hydralazine).
Stopping the drug typically leads to the resolution of clinical symptoms within weeks to months.

Key Concept

Drug-induced lupus erythematosus (DILE) presents with fever, polyarthritis, and serositis in a patient taking a high-risk medication (e.g., hydralazine, procainamide). It is characterized by positive ANA and anti-histone antibodies, but unlike idiopathic SLE, usually features normal complement levels and lacks severe renal or CNS involvement. Management consists of stopping the offending drug.
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Topics

Rheumatology and Immunology

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