Osteitis Deformans (Paget Disease of Bone)



  • Focal disorder of hyperactive bone resorption followed by excessive bone formation (remodeling) that is stimulated by abnormal osteoclasts
  • Results in enlarged, disorganized, weakened, and highly vascularized mosaic of bone
  • Painful condition, with easily deformed bone that is subject to fractures from minimal trauma
  • Most commonly affected sites:
    • Pelvis, spine, skull, extremities
  • Cranial and vertebral involvement can lead to neurologic deficits.
  • Synonym(s): Paget disease of bone; osteodystrophia deformans


  • Predominant age: >50 years
    • Less common in patients from ages 20 to 50 years
    • Does not occur in children (Juvenile Paget disease is unrelated to the adult disease.)
  • Predominant sex: males > females (1.8:1)


  • Prevalence increases with increasing age.
    • 2% among 55- to 59-year-old men, 20% among men >85 years (1)[C]
  • More common if Caucasian, especially in United Kingdom, France, Germany, Italy, United States, Australia, or New Zealand
    • 3% of Caucasians >50 years have at least one gene focus.
  • Rare in African Americans and Asians
  • Incidence and prevalence have decreased in recent years; likely due to genetic and environmental factors

Etiology and Pathophysiology

  • Unknown, although several theories proposed:
    • Slow viral infection (controversial): due to paramyxovirus, respiratory syncytial virus, canine distemper virus and measles; causing expression to develop over many years
    • Zoonotic infections
    • Toxin occupational exposure
    • Childhood malnutrition—vitamin D deficiency or low dietary calcium
  • Three pathologic phases:
    • Lytic phase: Osteoclasts are large, contain 10 to 100 nuclei, and have abnormal configuration.
    • Mixed phase: Excessive osteoblastic bone formation predominates from increase in number of osteoblasts; nonlinear collagen deposition results.
    • Sclerotic phase: Sclerotic bone–containing cement lines form a mosaic pattern (woven bone), with vasculature infiltration and fibrous connective tissue deposition.


  • At least seven genetic loci have been identified that are associated with Paget disease of bone.
  • Mutations in SQSTM1, predominately ubiquitin-binding associated (UBA) domain and P392L, are associated. Product of SQSTM1 affects osteoclast differentiation and activation.

Risk Factors

  • First-degree relative with osteitis deformans (OD)
    • 15–30% of patients note a family history of OD.
  • Caucasian and European ethnicity

General Prevention

Fracture reduction: Avoid excessive mechanical stress on afflicted bones.

Commonly Associated Conditions

  • Hyperparathyroidism
  • Gout
  • Secondary osteoarthritis
  • Peyronie disease
  • Accelerated atherosclerosis
  • Osteoporosis circumscripta
  • Frontotemporal dementia (rare)
  • Hereditary inclusion body myopathy (rare)
  • Bone sarcoma (rare)

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