Rheumatologists also treat a group of diseases called “systemic autoimmune diseases.” Other terms that you may hear or read that mean the same as systemic autoimmune diseases are “collagen vascular diseases,” and “connective tissue diseases.” This is a group of diseases where a person’s immune system attacks the person’s own body. This ends up causing inflammation in areas of the body where it is not needed, causing problems such as pain, swelling, and organ damage. These diseases can affect any part of the body including the eyes, skin, nerves, kidneys, lungs, heart, and other internal organs. All systemic autoimmune diseases can cause inflammation of the joints or arthritis. Therefore, rheumatologists are considered the experts in treating this group of disorders. Some examples of systemic autoimmune diseases include rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s disease, scleroderma, polymyositis, and vasculitis. However, there are more than 100 different types of arthritis and musculoskeletal conditions. Many rheumatologists also conduct research to look for the causes of and better treatments for rheumatic diseases. While the role of an orthopedic surgeon is to perform surgery on bones and joints (the musculoskeletal system), the purpose of the rheumatologist is to diagnose what type of musculoskeletal disease a person has and to treat it using nonsurgical methods.