Ref Robbins 8/e p225;518; Harrison 18/e p2096,9/e p228- 229 Systemic sclerosis (SS) is an immunologic disorder characterized by excessive fibrosis in multiple tissues, obliterative vascular disease, and evidence of autoimmunity, mainly the production of multiple autoantibodies. It is commonly called scleroderma because the skin is a major target, but this disorder is better labeled "systemic" because lesions are present throughout the body. Cutaneous involvement is the usual presenting manifestation and eventually appears in approximately 95% of cases, but it is the visceral involvement--of the gastrointestinal tract, lungs, kidneys, hea, and skeletal muscles--that is responsible for most of the related mor- bidity and moality. SS can be classified into two groups on the basis of its clinical course: * Diffuse scleroderma, characterized by initial widespread skin involvement, with rapid progression and early vis- ceral involvement * Limited scleroderma, with relatively mild skin involve- ment, often confined to the fingers and face. Involve- ment of the viscera occurs late, so the disease in these patients generally has a fairly benign course. This clini- cal presentation is also called the CREST syndrome because of its frequent features of calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia.