Collagen vascular disease occurs when problems with the immune system affect collagen. Collagen is a tough, fiber-like protein that makes up 30% of body protein. It contributes to the structure of tendons, bones, and connective tissues. In a class of diseases known as autoimmune disorders, the body's immune system attacks its own tissues. Some of these diseases have similarities, including arthritis and inflammation of arteries in the tissues that connect joints and other tissues. These diseases are known as collagen vascular diseases. Collagen vascular diseases include:Ankylosing spondylitis; Dermatomyositis; Polyarteritis nodosa; Psoriatic arthritis; Rheumatoid arthritis; Scleroderma; Systemic lupus erythematosus