Rheumatologists have particular skills in the evaluation of the over 100 forms of arthritis, and have special interest in rheumatoid arthritis, spondylitis, psoriatic arthritis, systemic lupus erythematosus, antiphospholipid antibody syndrome, Still's disease, dermatomyositis, Sjögren's syndrome, vasculitis, scleroderma, mixed connective tissue disease, sarcoidosis, Lyme disease, osteomyelitis, osteoarthritis, back pain, gout, pseudogout, relapsing polychondritis, Henoch- Schönlein purpura, serum sickness, reactive arthritis, Kawasaki disease, fibromyalgia, erythromelalgia, Raynaud's disease, growing pains, iritis, osteoporosis, reflex sympathetic dystrophy, and others.