Rheumatology is the specialty of Internal Medicine that encompasses the diagnosis and treatment of musculoskeletal and autoimmune disorders which can cause a variety of symptoms, including joint and muscle pain and swelling, stiffness, and deformity. Many of these disorders can affect other organ systems such as the heart, lungs, skin, and kidneys. Common disorders treated by rheumatologists include osteoarthritis, rheumatoid arthritis, lupus, gout, and fibromyalgia.