Paget disease (bone)

Paget disease of the bone is a common, chronic bone disorder characterized by excessive abnormal bone remodelling. The classically described radiological appearances are expanded bone with a coarsened trabecular pattern. The pelvis, spine, skull, and proximal long bones are most frequently affected.

It is relatively common and can affect up to 4% of individuals over 40 and up to 11% over the age of 80 1. There may be a slight male predilection. Incidence can be considerably higher in the United Kingdom than in other countries 8. It is also common in Australia, New Zealand, Western Europe, and the United States.

The majority (approximately three-quarters) of patients are asymptomatic at the time of diagnosis. Presenting symptoms include:

  • localized pain and tenderness
  • increased focal temperature due to hyperemia (due to hypervascularity)
  • increased bone size: historically changing hat size was a giveaway
  • bowing deformities
  • kyphosis of the spine
  • decreased range of motion
  • signs and symptoms relating to complications (see below)

Polyostotic disease is more prevalent than the monostotic type 1. The most frequent sites of involvement are:

  • spine
  • pelvis (often asymmetric)
  • skull
  • proximal long bones

The etiology is not entirely known, but it is a disease of osteoclasts. Viral infection (paramyxovirus) 6 in association with genetic susceptibility has been postulated.

There are three classically described stages, which are part of a continuous spectrum:

  • early destructive stage (incipient active, lytic): predominated by osteoclastic activity
  • intermediate stage (active, mixed): osteoblastic as well as osteoclastic activity
  • late stage (inactive, sclerotic/blastic)

These stages correlate well with the imaging findings.

  • elevated serum alkaline phosphatase
  • normal calcium and phosphorous levels
  • increased urine hydroxyproline

The early phase features osteolytic (lucent) region which is later followed by coarsened trabeculae and bony enlargement. Sclerotic changes occur much later in the disease process.

  • picture frame sign: Paget disease of the spine frequently manifests with cortical thickening and sclerosis encasing the vertebral margins, which gives rise to this appearance on radiographs in mixed phase disease
  • squaring of vertebrae: on lateral radiographs, flattening of the normal concavity of the anterior margin of the vertebral body also adds to the rectangular appearance
  • vertical trabecular thickening: coarser than the more delicate pattern seen in intraosseous hemangiomas with which it may be confused
  • cortical thickening and sclerosis of the iliopectineal and ischiopubic lines
  • acetabular protrusion
  • enlargement of the pubic rami and ischium

These findings are often asymmetric, and for some reason, are more commonly seen on the right side.

  • blade of grass or candle flame sign: begins as a subchondral area of lucency with advancing tip of V-shaped osteolysis, extending towards the diaphysis
    • in rare cases, the disease is isolated to the diaphysis, most commonly in the tibia, rather than subchondral bone, which can cause diagnostic confusion
  • lateral curvature (bowing) of the femur
  • anterior curvature of the tibia

Paget disease-related signs include:

The overall signal characteristics are variable, likely reflecting the natural course of the disease process in different phases.

Several major patterns of involvement have been described 8,16:

  • dominant signal intensity in Pagetic bone similar to that of fat; most common pattern and probably corresponds to longstanding disease
  • relatively low T1 and high T2 signal alteration (also referred as a “speckled” appearance); second most common pattern: probably corresponds to granulation tissue, hypervascularity, and edema seen in early mixed active disease
  • low signal intensity on both T1 and T2 images; suggesting the presence of compact bone or fibrous tissue; least common pattern: seen in late sclerotic stage

Fatty marrow signal is usually preserved in all sequences unless there is a complication 10.

  • Tc-99m-MDP
    • highly sensitive but not specific
    • traditionally has been said to demonstrate marked increased uptake in all phases of the disease, although in the burnt out sclerotic quiescent phase uptake may be normal 1

Symptomatic patients are treated with bisphosphonates (e.g. alendronate) aiming to reduce the bone turnover, to promote healing of osteolytic lesions and improve bone pain. Analgesics and non-hormonal anti-inflammatory drugs are also prescribed for pain management. 

Sir James Paget first described it in 1877 in a case report of a patient he had observed over some twenty years 5.

The condition was initially named by Paget "osteitis deformans", implying an inflammatory etiology. The term "osteodystrophica deformans" is now preferred.

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Article information

rID: 1824
Synonyms or Alternate Spellings:
  • Osteodystrophica deformans
  • Paget disease of the bone
  • Paget disease of bone
  • Osteitis deformans
  • Paget disease of the bones
  • Paget disease of bones
  • Paget's disease of bones
  • Paget's disease of the bones

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Cases and figures

  • Figure 1: histopathology
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  • Case 2
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  • CT Axial
    Case 3: skull
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  • Paget disease
    Case 4: pelvis
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  • Paget disease
    Case 5: distal femur
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  • Case 6: scapula
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  • Case 7: skull
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  • Case 8: with secondary osteosarcoma
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  • Case 9
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  • Case 10
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  • Case 11
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  • Case 12: involving sternum
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  • Case 13: on MRI
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  • Case 14
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  • External rotation...
    Case 15: rib
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  • Case 16
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  •  Case 17
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  • Case 18: polyostotic involvement
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  • Case 19
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  • Case 20
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  • Case 21
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  • Case 22: with blade of grass sign
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  • Case 23
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  • left hip
    Case 24: affecting femur
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  • Case 25: right iliac bone
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  • Case 26
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  • Case 27: pathological fractures
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  • Case 28
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  • Case 29: thumb
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