Systemic lupus erythematosus

Definition

• Multisystem inflammatory disorder of unknown etiology

ACR Classification Criteria

4 or more of the following (4RASHES mnemonic)

• Four dermatologic manifestations
  • Malar rash: spares nasolabial folds
  • Discoid rash: erythemaous plaques/patches
  • Photosensitivity: rash, not sunburn
  • Mucocutaneous ulcers: oropharynx or nasopharynx, often painless
• Renal disorder
  • Proteinuria >0.5g/d or 3+
  • Any cellular or granular casts
• Arthritis: non-erosive involving 2 or more joints
• Serositis: pleuritis or pericarditis
• Hematologic disorder
  • Hemolytic anemia
  • Leukopenia
  • Lymphopenia: most important
  • Thrombocytopenia
• Neurological excitability
  • Seizures
  • Psychosis
• Serology (non-ANA)
  • Anti-dsDNA antibodies
  • Anti-Sm antibodies
  • Anti-phospholipid antibodies
• Serology (ANA): most sensitive finding (~98%)

Clinical Manifestations

• See above criteria
• Fevers and other constitutional symptoms
• Any other non-specific rash, even if not in criteria
  • Discoid rash forms scars
• Alopecia, either discrete or global

Investigations

• Most important tests
  • CBC for lymphopenia & other hematologic abnormalities
  • Urinalysis for active sediment
• Serology
  • ANA most sensitive, anti-Smith and anti-dsDNA are most specific
  • APLA
  • Can be either seroconcordant or -discordant for dsDNA, C3/C4, ESR/CRP during flares

Management

Acute

• Prednisone 0.5-1mg/kg depending on severity
• Cyclophosphamide if severe or renal involvement
• vs. MMF

Chronic

• Hydroxychloroquine
  • Load with 400-600mg TDD split BID for 1-3 months
  • Step down to 6.75mg/kg maintenance
  • Needs ophtho follow-up for rare macular side effect
  • Best for skin
• Azathioprine as steroid-sparing agent