Paget disease is caused by increased bone remodeling and focal bone growth. It is a disease of osteoclasts that is generally seen in older adults and typically affects the skull, spine, pelvis, and long bones of the lower extremities. A common finding associated with aging, Paget disease is identified in 2%-9% of elderly patients, with age of onset at 55 years.

The disease is often asymptomatic but can cause bone pain, fractures, bone deformity, and symptoms due to compression of surrounding structures (eg, hearing loss, lumbar radicular pain). Genetics and viruses are suspected to play a role in causing the disease.

Bisphosphonates are used to treat the disease.