Paget disease

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[edit] Discussion

  • AKA osteitis deformans
  • Important not to confuse its imaging appearance with those of other diseases.
  • Complications of Paget disease include:
    • Deformity and
    • Arthritis
    • Neurologic symptoms
    • Neoplastic transformation

  • Paget disease is extraordinarily common, affecting 3%–4% of the population over 40 years of age and up to 10%–11% after 80 years of age.
  • Although Paget disease is unusual in people younger than 40 years of age.

  • Paget disease is characterized by excessive and abnormal remodeling of bone, with both active and quiescent phases.
  • Three phases
    • Lytic phase (incipient-active), in which osteoclasts predominate
    • Mixed phase (active), in which osteoblasts begin to appear
    • Blastic phase (late-inactive), in which osteoblastic activity gradually declines

  • Paget disease is predominantly located in the axial skeleton, with the most commonly affected sites being the pelvis (30%–75% of cases), spine (30%–75%), and skull (25%–65%)
  • Proximal long bones are also frequently involved, with the femur affected in 25%–35% of cases (2–5). Less commonly affected sites include the shoulder girdle and forearm (humerus, 31% of cases; scapula, 24%; and clavicle, 11%).
  • Involvement of other sites, including the ribs, fibula, bones of the hands and feet, calcaneus, patella, and tibial tubercle, is infrequent.

  • Monostotic disease (10%–35% of cases) is more often seen in the axial skeleton, although any site can be the sole region of involvement.
  • Polyostotic disease (65%–90%) is more frequent than monostotic disease, tends to have right-sided predominance, and usually involves lower extremities

[edit] Imaging Findings

[edit] Plain films

Lytic Phase

  • The early phase of Paget disease is characterized by osteolysis
  • In the skull, osteolysis is frequently seen as well-defined, often large areas of radiolucency most commonly affecting the frontal and occipital bones; these areas are referred to as osteoporosis circumscripta or osteolysis circumscripta.
    • Both inner and outer calvarial tables are involved, with the former usually more extensively affected.
    • This pattern is in contradistinction to that of fibrous dysplasia, which usually affects the outer table more prominently.

  • In the long bones, osteolysis begins as a subchondral area of lucency.
  • The advancing wedge of osteolysis often demonstrates a characteristic sharp radiolucent margin without sclerosis likened to a blade of grass or flame.
  • In rare cases, the disease is isolated to the diaphysis, most commonly in the tibia, rather than subchondral bone, which can cause diagnostic confusion

Mixed Phase

  • Vast majority of cases of Paget disease seen by radiologists are in the mixed phase.
  • Characteristic manifestations seen radiographically are coarsening and thickening of the trabecular pattern and cortex.
  • Trabecular thickening occurs primarily along the lines of stress, although disorganized areas are also seen.

  • Paget disease of the pelvis usually manifests with cortical thickening and sclerosis of the iliopectineal and ischiopubic lines.
  • These findings are often asymmetric and more commonly seen on the right side.
  • These manifestations are also often associated with enlargement of the pubic rami and ischium.

  • Paget disease of the spine frequently manifests with cortical thickening encasing the vertebral margins, which gives rise to the "picture frame" appearance on radiographs in mixed phase disease.
  • The osteoblastic activity is seen along all four margins of the vertebral body cortices, unlike the rugger jersey vertebrae in renal osteodystrophy, which only involves the superior and inferior endplates.
  • The vertical trabecular thickening pattern in Paget disease is coarser than the more delicate pattern seen in hemangiomas with which it can be confused.
  • Flattening or squaring of the normal concavity of the anterior margin of the vertebral body can be seen on the lateral spinal radiographs.

[edit] Images

Patient #1

Patient #2

Patient #3: Malignant transformation of Paget disease (osteosarcoma).

[edit] See Also

[edit] External Links

Goldminer: Paget

[edit] References

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