Behçet's disease (BD) is a chronic inflammatory condition involving several organs, such as skin, mucous membrane, eye, joint, intestine, lung and central nervous system. Ankylosing spondylitis (AS) is a prototype of seronegative spondyloarthropathy, and a chronic systemic inflammatory disorder of the axial skeleton, mainly affecting the sacroiliac joint and spine. In the latter, systemic compl...