Types of Paget's disease

Paget's disease of bone is usually described by how many bones are involved and how active the disease is. It is not divided into formal subtypes the way many other diseases are.

By number of bones

• Monostotic: only one bone is affected. Often the pelvis, spine or a leg bone.
• Polyostotic: more than one bone is affected, which is more common

By site

• Pelvis, spine and skull are the most frequent
• Femur and tibia (thigh and shin) are next
• Collarbone, shoulder and arm bones less often
• Hands and feet are rarely involved

By activity

• Active disease: blood alkaline phosphatase is high and a bone scan shows increased uptake
• Inactive disease: markers return to normal, often after treatment

Related conditions

• Familial forms: run in families, may start earlier
• Early-onset Paget's disease of bone is uncommon and often genetic
• Other bone diseases such as osteoporosis, osteomalacia, metastatic bone disease and fibrous dysplasia can look similar on a scan and need to be ruled out