Scleroderma is a disease of mesenchymal tissues characterized by fibrosis and vascular changes which eventually lead to organ insufficiency. Two clinical forms have been recognized, localized and systemic scleroderma. The localized form only affects the skin and the lesions have a tendency to resolve spontaneously. Systemic scleroderma is a progressive, usually irreversible process and the organs most frequently involved are the skin, gastrointestinal tract, lungs and kidneys. The following findings strongly suggest that involvement of small blood vessels (capillaries, arterioles and small size arteries) plays an important role in the pathogenesis of systemic scleroderma: (a) the frequent presence of Raynaud's phenomenon, (b) marked reduction in the number of dermal capillaries, (c) increase in thickness of the basement membrane of muscle capillaries (16), (d) thickening and hyalinization of arterioles (e) intimal proliferation of small size arteries, and (f) eventual ischemic necrosis (2, 3, 17). Small b...