Microvascular changes in progressive systemic sclerosis: immunohistochemical and ultrastructural study

Fifteen patients affected by Progressive Systemic Sclerosis have been studied. With immunofluorescence, specific antibodies against collagen type IV and laminin clearly outlined the microvessels, while endothelial cells showed a brilliant heavy fluorescence for vimentin antibodies. In the deep dermis, fibronectin proved to have increased. At electron microscopy, microvessels appeared with occluded lumina due to the presence of swollen endothelial cells. Endothelial cytoplasm was filled with intermediate filaments (vimentin type), generally condensed into peripherally located bundles or in perinuclear rings. The perivascular basal lamina was thickened and laminated. Although these changes do not demonstrate a specific pattern, representing a common step in several connective tissue disorders, the data tend to confirm a clear involvement of the microvasculature in Progressive Systemic Sclerosis.