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 0.5-1 mg/kg depending on severity
- Cyclophosphamide if severe or renal involvement
- vs. MMF
Chronic
- Hydroxychloroquine
- Load with 400-600 mg TDD split BID for 1-3 months
- Step down to 6.75 mg/kg maintenance
- Needs Ophthalmology follow-up for rare macular side effect
- Best for skin
- Azathioprine as steroid-sparing agent
