Polyarthritis: Differential diagnosis: 1) rheumatoid arthritis 2) SLE 3) seronegative spondyloarthropathies 4) Henoch-Schonlein purpura 5) sarcoidosis 6) tuberculosis 7) pseudogout 8) viral infection: EBV, HIV, hepatitis, mumps, rubella Systemic lupus erythematosus Epidemiology: much more common in females (F:M = 9:1) more common in Afro-Caribbean’s* and Asian communities onset is usually 20-40 years incidence has risen substantially during the past 50 years (3 fold using American College of Rheumatology criteria) *It is said the incidence in black Africans is much lower than in black Americans - the reasons for this are unclear Pathophysiology: autoimmune disease associated with HLA B8, DR2, DR3 thought to be caused by immune system dysregulation leading to immune complex formation immune complex deposition can affect any organ including the skin, joints, kidneys and brain Features: Systemic lupus erythematosus (SLE) is a multisystem, autoimmune disorder. General features: fatigue fever mouth ulcers lymphadenopathy Skin: malar (butterfly) rash: spares nasolabial folds Discoid rash: scaly, erythematous, well demarcated rash in sun-exposed areas. Lesions may progress to become pigmented and hyperkeratotic before becoming atrophic photosensitivity Raynaud's phenomenon livedo reticularis non-scarring alopecia [1]