The early pathological changes of SSc include swelling and homogenization of collagen fibers, and perivascular and collagen fiber infiltration by lymphocytes dominantly, followed by increase in dense collagen fibers in reticular dermis, thinning of the epidermis, disappearance of Rete ridges, atrophy of sebaceous glands and decrease in sweat glands. Besides, thickening of the vascular wall and stenosis or even occlusion of the lumen can also be seen. The damage to internal organs is mainly caused by the hyperplasia and sclerosis of the mesenchyma and the collagen fibers in vascular wall. Esophageal involvements include atrophy of the smooth muscle, while fibrosis happens in submucosa and lamina propria, and mucosa shows varying degrees of thinning and erosion. Fibrosis change also shows in the nutrient vessels of esophagus. Barrett metaplasia can happen in 1/3 of the SSc patients. As for the lungs, Pulmonary fibrosis and pulmonary vascular lesions often coexist. Pulmonary fibrosis is often severer in Scl-70 positive diffuse sclerosis patients, and What can be seen in patients with pulmonary hypertension are pulmonary interstitial and peribronchial fibrosis, and medial hyperplasia of pulmonary arterioles. Autopsy showed that hyperplasia of intima in small pulmonary arteries occurs in about 29%-47% of the patients.