Each participating center was asked to submit data on 10 to 12 consecutive patients with a clinical diagnosis of SLE and 12 to 15 controls. The controls were to consist of consecutively seen patients with one of the following diagnoses: rheumatoid arthritis, myositis, chronic cutaneous lupus, undifferentiated connective tissue disease, vasculitis, primary antiphospholipid antibody syndrome, scleroderma, fibromyalgia, Sjögren syndrome, rosacea, psoriasis, sarcoidosis and juvenile idiopathic arthritis. Because it was recognized that important control groups , including chronic cutaneous lupus, which had not necessarily been part of previous efforts, needed to be represented, cases were also contributed by a number of dermatologists.