Introduction:
https://www.youtube.com/watch?v=FnPFD8GiHs8
Paris Nomenclature of Constitutional Diseases of the Bone naming scheme for diseases associated with fibrous dysplasia (FD):
| Form | Single bone inovlvement | Multiple bone inovlvement | Café-au-lait spots | Endocrine disorders | Intramuscular myxomas |
|---|---|---|---|---|---|
| Monostotic form | + | ||||
| Polyostotic form | + | ||||
| McCune-Albright syndrome | + | + | + | ||
| Mazabraud syndrome | + | + |
Mutation timing determines the extent of the disease and clinical manifestations.
The stage of embryogenesis during which a mutation occurs, and the locations to where mutated progenitors subsequently migrate, determines if a patient will have a single lesion, polyostotic disease or one of the FD-related syndromes. Mutations that occur at early stages of embryogenesis result in the widespread distribution of the lesions. Mutations that develop at late stages of embryogenesis lead to more focused distribution of the lesions. Patients with McCune-Albright syndrome (MAS) may have different extra-skeletal abnormalities. Some of these abnormalities may progress to malignancy; part of them become stable throughout life; some abnormalities can regress or disappear
Kushchayeva, Y.S., Kushchayev, S.V., Glushko, T.Y. et al. Fibrous dysplasia for radiologists: beyond ground glass bone matrix. Insights Imaging 9, 1035–1056 (2018). https://doi.org/10.1007/s13244-018-0666-6
Histopathology:
https://www.youtube.com/watch?v=MKo8q0qwHvU
https://doi.org/10.1007/s13244-018-0666-6
Radiographic appearance:
Varied appearance depending on tissue composition:
The radiographic appearance of fibrous dysplasia (FD) and the rind sign. a–e Frontal radiographs demonstrate classic FD lesions in appendicular skeleton. A classic lucent lesion surrounded by a layer of sclerotic reactive bone (so-called the rind sign). The rind sign is most commonly seen in the proximal femur (red arrow)
Kushchayeva, Y.S., Kushchayev, S.V., Glushko, T.Y. et al. Fibrous dysplasia for radiologists: beyond ground glass bone matrix. Insights Imaging 9, 1035–1056 (2018). https://doi.org/10.1007/s13244-018-0666-6
FD of femur:
The classification of femur deformities in fibrous dysplasia (FD):
a: Type 1: The neck-shaft angle is within normal limits (135°), but a distal femur shows 16° valgus deformity. b: Type 2: The neck-shaft angle is valgus (152°). c: Type 3: The neck-shaft angle is varus (100°). A distal shaft 10° demonstrates varus deformity. Distal juxta-articular valgus deformity is also present. d: Type 4: The neck-shaft angle is normal (125°). Proximal lateral (shepherd’s crook) and distal medial bowing of the femoral shaft are present. e: Type 5: The neck-shaft angle is valgus (160°). Lateral bowing of the proximal femur (shepherd’s crook) and medial bowing of the distal femur are present. f: Type 6: FD affects the entire femur. Lateral bowing of the proximal femur is present at two levels (shepherd’s crook) as well as medial bowing of the distal femur. The neck-shaft angle is varus (100°)
Ippolito E, Farsetti P, Boyce AM, Corsi A, De Maio F, Collins MT (2014) Radiographic classification of coronal plane femoral deformities in polyostotic fibrous dysplasia. Clin Orthop Relat Res 472:1558–1567