Paget's disease of bone (commonly known as Paget's disease or historically, osteitis deformans) is a condition involving cellular remodeling and deformity of one or more bones. The affected bones show signs of dysregulated bone remodeling at the microscopic level, specifically excessive bone breakdown and subsequent disorganized new bone formation. These structural changes cause the bone to weaken, which may result in deformity, pain, fracture, or arthritis of associated joints. Holding, then, the disease to be an inflammation of bones, I would suggest that, for brief reference, and for the present, it may be called, after its most striking character, Osteitis deformans. A better name may be given when more is known of it. Paget's disease of bone (commonly known as Paget's disease or historically, osteitis deformans) is a condition involving cellular remodeling and deformity of one or more bones. The affected bones show signs of dysregulated bone remodeling at the microscopic level, specifically excessive bone breakdown and subsequent disorganized new bone formation. These structural changes cause the bone to weaken, which may result in deformity, pain, fracture, or arthritis of associated joints. The exact cause is unknown, although leading theories indicate both genetic and acquired factors (see causes). Paget's disease may affect any one or multiple bones of the body (most commonly pelvis, femur, and lumbar vertebrae, and skull), but never the entire skeleton, and does not spread from bone to bone. Rarely, a bone affected by Paget's disease can transform into a malignant bone cancer. As the disease often affects people differently, treatments of Paget's disease can vary. Although there is no cure for Paget's disease, medications (bisphosphonates and calcitonin) can help control the disorder and lessen pain and other symptoms. Medications are often successful in controlling the disorder, especially when started before complications begin. Paget's disease affects from 1.5 to 8.0 percent of the population, and is most common in those of British descent. It is primarily diagnosed in older people, and is rare in people less than 55 years of age. Men are more commonly affected than women (3:2). The disease is named after Sir James Paget. Mild or early cases of Pagets are asymptomatic, and so most people are diagnosed with Paget's disease incidentally during medical evaluation for another problem. Approximately 35% of patients with Paget's have symptoms related to the disease when they are first diagnosed. Overall, the most common symptom is bone pain. When symptoms do occur, they may be confused with those of arthritis or other disorders, and so diagnosis may be delayed.