The acutely affected kidney may not show much in the way of gross pathologic features. An occasional infarct may be discerned. The healed or chronically affected kidney shows reduction of cortical mass and fine cortical surface scarring similar to that of nephrosclerosis. The histology of scleroderma in the acute phase is that of a thrombotic microangiopathy. The structures that are most involved are the interlobular arteries.
Interlobular arteries show intimal thickening that is loose, myxoid and edematous.
Fibroblasts and red cell fragments may be present in the thickened intima. Fibrin thrombi may occlude lumens. Chronic or healed arterial lesions show concentric intimal fibroelastosis. The disease is manifest by excess fibrosis in organs throughout the body. Tissues frequently involved are skin, gastrointestinal tract, kidneys, heart, muscles and lungs.