Rheumatology is a subspecialty of Internal Medicine. We provide specialty care for patients with arthritis, certain autoimmune diseases, musculoskeletal pain disorders and osteoporosis. There are more than 100 types of these diseases, including rheumatoid arthritis, osteoarthritis, gout, lupus, back pain, osteoporosis, and tendonitis. Some of these are very serious diseases that can be difficult to diagnose and treat. A rheumatologist is an internist or pediatrician who is qualified by additional training and experience in the diagnosis and treatment of arthritis and other diseases of the joints, muscles and bones. Your regular doctor will refer you to a rheumatologist when you have a rheumatologic problem.