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Case 305 - Discussion

Uploaded: 2009-08-15, Updated: 2009-08-15

Paget's disease of the bone, lytic phase

  • Characteristic exaggerated, nonphysiologic bone remodeling.

  • 3-4% of adults over the age of 50, 10-15% over the age of 80.

  • Usually polyostotic, 15% only one bone involved.

  • Most common location, pelvis, spine and skull (axial), also femur and tibia.

  • Radiographic:

    • Initial (hot) phase: slowly growing, well-circumsribed focus of radiolucency. Long bone, a wedge or flame-shaped area of lucency in the metaphysis with apex pointed to the diaphysis.

    • Intermediate phase: variable mixture of the radiolucent and radiodense features.

    • Late (cold) phase: progressive radiodensity. Long bone, coarsening of trabeculea, blurring of the cortical-medullary junction, narrowing of the medullary canal and thickening or enlargement of the bone.

  •  Micro:

    • Initial (hot) phase: rapid bone resorption with large and irregular resorption cavities, marrow replacement y vascular fibrous tissue and abundant enlarged osteoclasts.

    • Intermediate phase: increase in bone formation, abundant osteoblastic activity, irregular and thichened osteoid seams and abundant woven bone.

    • Late (cold) phase: less osteoclastic and osteoblastic activity, mosaic pattern of intersecting cement lines. The woven bone is covered to lamellar bone, indistinct medullary-cortical junction.

  • Differential:

    • Osteoblastoma: irregular foci of mineralization, lack of giant osteoclasts, no remnants of native trabecular bone, only contains woven bone.

    • Fibrous dysplasia: centered in the medullary cavity, ground glass texture; lack of giant osteoclasts, no remnants of native trabecular bone, only contains woven bone.