Fibrous Dysplasia
Epidemiology:
- Monostotic (70%):
- Polyostotic (27%):
Common sites:
- Monostotic:
- Ribs, femur, tibia,
jawbones, calvaria, humerus
- Polyostotic:
- Femur, skull,
tibia, humerus, ribs, fibula, radius, ulna, mandible,
vertebrae
- McCune-Albreight:
- Often unilateral
with ipsilateral skin pigmentation
Gross features:
- Well-circumscribed
- Intramedullary
- Tan-white
- gritty
Histologic features:
- curvilinear trabeculae of woven bone (mimic Chinese characters)
- moderately
cellular fibroblastic proliferation
- nodules of hyaline cartilage with appearance
of disorganized growth plate (20%)
- cystic
degeneration
- hemorrhage
- foamy macrophages
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- 3 clinical
patterns (may overlap):
- single bone (monostotic)
(70%)
- often
stops growing at time of growth plate closure
- multiple (but not all) bones (polyostotic) (27%)
- continues
to cause problems into adulthood
- polyostotic with café au lait
spots and endocrine abnormalities (esp. precocious puberty) (McCune-Albright
syndrome)
- radiology:
- typical
ground-glass appearance
- well-defined
margins
References: