When should rheumatologic (relating to rheumatology) causes of pleurisy be considered?

When to Consider Rheumatologic Causes of Pleurisy

Rheumatologic causes of pleurisy should be considered when a patient presents with pleuritic pain and has either established rheumatologic disease, characteristic pleural fluid findings, or when other common causes have been excluded. 1

Clinical Scenarios Warranting Consideration of Rheumatologic Causes

1. In Patients with Known Rheumatologic Disease

• Rheumatoid arthritis (RA): Pleural involvement occurs in approximately 5% of patients with RA 1

  • More common in men despite RA being more prevalent in women 2
  • Often seen in patients with long-standing disease, positive rheumatoid factor, and subcutaneous nodules 2

• Systemic lupus erythematosus (SLE): Up to 50% of patients with SLE will develop pleural disease during their illness 1

  • Pleural involvement is the most common pulmonary manifestation in SLE 1

2. In Patients with Unexplained Pleurisy

Consider rheumatologic causes when:

• Common causes (infection, malignancy, pulmonary embolism) have been excluded 1
• Pleural fluid analysis shows characteristic findings:
  • For RA: Low glucose (<1.6 mmol/l or 29 mg/dl), low pH, low complement levels 1
  • For SLE: Presence of LE cells in pleural fluid (diagnostic of SLE) 1

Diagnostic Approach

Initial Evaluation

• Joint examination (swelling/tenderness) and functional assessment 1
• Laboratory testing:
  • Antinuclear antibody (ANA)
  • Rheumatoid factor (RF)
  • Anti-cyclic citrullinated peptide antibody (anti-CCP)
  • Erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP) 1

Pleural Fluid Analysis

• For suspected RA-related pleurisy:

  • Measure pleural fluid pH, glucose, and complement levels 1
  • RA is unlikely if glucose level is above 1.6 mmol/l (29 mg/dl) 1

• For suspected SLE-related pleurisy:

  • Look for LE cells (diagnostic of SLE) 1
  • Note: Pleural fluid ANA testing is not recommended as it mirrors serum levels and is unhelpful 1

Imaging

• Consider plain X-ray of affected joints
• Joint MRI and/or musculoskeletal ultrasound if indicated 1
• High-resolution CT (HRCT) for patients with suspected interstitial lung disease (ILD), particularly in inflammatory myopathies with anti-MDA5 or anti-synthetase antibodies 1

When to Refer to Rheumatology

• All patients with CTCAE ≥ grade 2 inflammatory arthritis 1
• Any patient with persistent symptoms for >6 weeks 1
• Any patient requiring >20 mg prednisone (or equivalent) daily that cannot be tapered to <10 mg/day within 4 weeks 1
• All patients with suspected rheumatologic manifestations (including pleurisy) should be referred to rheumatology even if symptoms are mild, to ensure appropriate diagnostic testing and management to prevent permanent organ damage 1

Management Considerations

• For rheumatoid pleurisy:

  • Corticosteroids are usually administered 2
  • Immunosuppressive drugs may be added when pulmonary disease progresses or steroid side effects appear 2
  • For patients unable to taper below 10mg daily of prednisone after 3 months, consider adding a disease-modifying antirheumatic drug (DMARD) 3

• For SLE-related pleurisy:

  • Treatment typically follows standard SLE management protocols
  • Regular monitoring with pulmonary function tests and chest radiography as clinically indicated 1

Important Clinical Pearls

• Rheumatoid pleurisy can occasionally be the initial manifestation of RA, preceding joint symptoms 4
• Pleural effusions in RA can be serous, turbid, yellow-green, milky, or hemorrhagic 1, 5
• Erosive, irreversible joint damage can occur within weeks of symptom onset in inflammatory arthritis, making early rheumatology referral crucial 1
• In HIV-positive patients, the differential diagnosis for pleural effusion is broader and includes Kaposi's sarcoma, parapneumonic effusions, and tuberculosis 1

By maintaining a high index of suspicion for rheumatologic causes of pleurisy, particularly in patients with unexplained pleural effusions or known rheumatologic disease, clinicians can ensure timely diagnosis and appropriate management to prevent long-term complications.