(a) Serum levels of vascular endothelial growth factor (VEGF) in patients with established systemic sclerosis (SSc) and in healthy controls. Data are shown as box plots, with upper and lower quartiles shaded. Highly significant differences were found for serum levels of VEGF compared with healthy controls. (b) Serum levels of VEGF analyzed according to the disease subset. Patients with diffuse SSc showed significant higher levels of VEGF than did patients with limited SSc. #P < 0.05.