Dermatologic changes occur in a variety of rheumatic diseases. Skin can be the initial site of involvement, thus providing important clues for an accurate diagnosis based on cutaneous findings. Dermatologic findings can also be an indicator of systemic involvement and prognostic outcome; however, many connective tissue disorders have a wide variety of cutaneous manifestations, with significant overlap between different diseases. These skin signs often precede systemic clinical manifestations. Careful attention to characteristic dermatologic findings in Behcet's disease, systemic lupus erythematosus, rheumatoid arthritis, and various vasculitis can provide prompt therapeutic approaches in the case of life-threatening complications of systemically involved rheumatologic diseases. (C) 2019 Elsevier Inc. All rights reserved.