Paget's disease. Coloured magnetic resonance imaging (MRI) scan of a sagittal section through the skull of a 60 year old patient with Paget's disease. The skull has become thickened (white). Paget's disease, or osteitis deformans, is a chronic bone disease that results in enlarged or deformed bones. The rate of bone reabsorption and formation become out of balance, leading to structurally disorganised, weaker and enlarged bone. Treatment is not usually required, but can be with painkillers or bisphosphonates, which slow the abnormal process and promote growth of normal bone.