Paget's Disease

Paget's Disease is a bone disorder characterized by unique histological findings. In this disease, an initial rise in osteoclast activity is followed by a stage in which osteoclasts and osteoblasts are both active, and finally by a stage in which osteoblasts dominate. The result is an increase in bone mass, but the bone is exaggerated, disorganized, and dysfunctional. Histologically, the bone appears in a mosaic pattern, with thick cement lines that demarcate randomly oriented lamellar bone. The exaggerated trabeculae and disorganized cortices result in a lack of ability to resist deformation, and greatly increased vulnerability to fracture.