MUSCULOSKELETAL
Etiology
Autoimmune disorder with loss of self-tolerance; genetic predisposition (HLA-DR2/DR3), environmental triggers (UV light, infections, drugs)
Clinical Features
Autoantibody formation → immune complex deposition in tissues → complement activation → multisystem inflammation (joints, skin, kidneys, serosa).
Symmetrical non-erosive arthritis; malar (“butterfly”) rash; photosensitivity; oral ulcers; serositis; renal and CNS involvement.
Diagnosis
ANA positive; anti-dsDNA and anti-Sm antibodies; ↓ complement levels; clinical criteria (joint, skin, renal, hematologic findings).
Treatment
Mild: NSAIDs, hydroxychloroquine.
Moderate–severe: Corticosteroids, immunosuppressants (azathioprine, mycophenolate, cyclophosphamide).
- Sun protection, avoid triggers.