Paget Disease



  • Paget disease involves resorption of normal bone and its replacement with fibrous and sclerotic tissue
  • Also known as osteitis deformans
  • Usually focal, bones most frequently involved include:
    • Pelvis
    • Femur
    • Skull
    • Tibia
    • Spine
    • Flat bones
  • Usually found incidentally and generally asymptomatic
  • Occurs in ∼1–2% of patients >55 yr old
  • Incidence increases with age
  • Starts with resorptive or osteolytic phase, during which osteoclasts remove healthy bone
  • Hypervascularity begins in resorptive phase:
    • Predisposes to hematoma and fracture
  • Resorbed bone is eventually replaced by irregular, dense, disorganized trabecular bone in sclerotic or osteoplastic phase forming “mosaic pattern”
  • Malignant transformation is rare:
    • Osteosarcoma is malignancy of concern
    • Usually malignant transformation occurs in 1%
  • More common in men
  • More common in European descent
  • Less common in Asian or Scandinavian descent
  • Typically involves 1 bone (monostotic)
  • May involve a few bones (polyostotic)


  • Unknown
  • Genetic component:
    • SQSTM1 mutation seen in many but not all cases
    • Patients with this mutation may present at a younger age
    • Paget disease may have genetically linked mutations seen in multisystem proteinopathies such as ALS and frontotemporal dementia
  • Environmental influences may also play a role:
    • Presence of nucleocapsids from measles, canine distemper, paramyxovirus, or respiratory syncytial virus may implicate viral cause
    • Possible association with rural life and close contact with farm animals
  • May represent vascular hyperplasia with subsequent inflammation
  • Increased nucleoli and intranuclear inclusion bodies seen in osteoclasts on microscopy

Pediatric Considerations
Generally not seen in children

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