Fibrous Dysplasia

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Fibrous Dysplasia

• Fibrous dysplasia is a developmental abnormality
  in which osteoblasts do not undergo normal
  differentiation and maturation
• Approximately 70-80 are monostotic and 20-30
  are polyostotic
• Fibrous dysplasia not uncommonly involves the
  skull and facial bones, usually the frontal,
  sphenoid, maxillary and ethmoid bones, although
  the case presented here involves the occiput
• Radiographically, mixed radiolucent and sclerotic
  lesions are seen, often with expansion (arrow)

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Fibrous Dysplasia

• Nuclear medicine bone scan may show increased
  uptake in sites of fibrous dysplasia such as this
  static image from a three phase bone scan
  demonstrating increased uptake in the occiput,
  corresponding to the radiographic abnormality

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Fibrous Dysplasia

• Computed tomography (CT) may show the internal
  fibrous matrix better than conventional
  radiographs (arrows)

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