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Characteristic exaggerated,
nonphysiologic bone remodeling.
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3-4% of adults over the age of 50,
10-15% over the age of 80.
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Usually polyostotic, 15% only one
bone involved.
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Most common location, pelvis, spine
and skull (axial), also femur and tibia.
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Radiographic:
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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.
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Intermediate phase:
variable mixture of the radiolucent and radiodense features.
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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.
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Micro:
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Initial (hot) phase:
rapid bone resorption with large and irregular resorption
cavities, marrow replacement y vascular fibrous tissue and
abundant enlarged osteoclasts.
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Intermediate phase:
increase in bone formation, abundant osteoblastic activity,
irregular and thichened osteoid seams and abundant woven
bone.
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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.
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Differential:
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Osteoblastoma: irregular foci
of mineralization, lack of giant osteoclasts, no remnants of
native trabecular bone, only contains woven bone.
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Fibrous dysplasia: centered in
the medullary cavity, ground glass texture; lack of giant
osteoclasts, no remnants of native trabecular bone, only
contains woven bone.
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