Sample Teaching Cases

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While computed tomography and magnetic resonance imaging are used in musculoskeletal imaging, the diagnosis can frequently be determined by conventional radiography.

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1. How many phases are expressed in this disease? What pathophysiology produces the radiographic findings in each phase?

2. Which bones are most commonly affected?

3. What complications can be seen? Which is most concerning?


Paget’s disease


Radiograph of the pelvis reveals thickened cortex and coarsened trabeculae throughout the sacrum, pelvis and visualized bilateral femora. While not clearly demonstrated, there is sparing of the lumbar vertebrae. Additionally there is join space narrowing and early protrusio acetabuli of the right hip.

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1. Which bones are most commonly affected by this disease?

Asymmetrical polyostotic involvement is more common than monostotic disease with the commonly affected sites as follows:

  • Pelvis
  • Vertebrae (lumbar > thoracic > cervical)
  • Skull
  • Proximal femur
  • Tibia
  • Humerus

2. How many phases are expressed in this disease? What pathophysiology produces the radiographic findings in each phase?

Paget’s disease progresses through three phases…an initial osteoclastic phase, an intermediate mixed osteoclastic/osteoblastic phase and a final predominantly osteoblastic phase. Findings in the initial osteoclastic phase reflect osteolytic processes. In the mixed phase both osteolysis and new bone formation are seen. The final phase results in increased cotical bone density and thickened trabeculae.

3. What complications are seen in this disease? Which is most concerning?

Symptoms depend on bone involvement with pain being the most frequent complaint. Weakening of bones can result in stress fractures, basilar invagination and protrusio acetabuli. Secondary osteoarthritis can occur in joints if adjacent bone is involved. The most concerning sequelae are malignant sarcomatous transformation of Pagetoid bone and boney enlargement causing narrowing of osseous canals with resulting neurologic and vascular compromise.

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