Fibrous dysplasia: Difference between revisions
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(Created page with "{{DISPLAYTITLE:Fibrous dysplasia (FD)}} = Introduction = * A benign fibro-osseous lesion of immature mesenchymal cells. * Commonly affects long bones, ribs, and skull. = Pathophysiology = * Originates from mutated pluripotent embryonic cells leading to skeletal stem cells. * Lesions form as cancellous bone is replaced with fibrous tissue and immature woven bone. * Monostotic FD (70% of cases) vs. Polyostotic FD. === Slide 3: Clinical Presentation === * Monostotic F...") |
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= Introduction = | = Introduction = | ||
* A benign fibro-osseous lesion of immature mesenchymal cells. | * A benign fibro-osseous lesion of immature mesenchymal cells. | ||
* Commonly affects long bones, ribs, and skull. | * Commonly affects long bones, ribs, and skull. | ||
= Pathophysiology = | = Pathophysiology = | ||
* Originates from mutated pluripotent embryonic cells leading to skeletal stem cells. | * Originates from mutated pluripotent embryonic cells leading to skeletal stem cells. | ||
* Lesions form as cancellous bone is replaced with fibrous tissue and immature woven bone. | * Lesions form as cancellous bone is replaced with fibrous tissue and immature woven bone. | ||
* Monostotic FD (70% of cases) vs. Polyostotic FD. | * Monostotic FD (70% of cases) vs. Polyostotic FD. | ||
=== | == Genetic Basis and Related Syndromes == | ||
* Genetic mutation: Chromosome 20q13 at the GNAS1 locus. | |||
* Constitutively active mutant of the α subunit of the G protein (Gsα). | |||
* McCune-Albright syndrome: Characterized by polyostotic FD, endocrinopathy, café au lait spots. | |||
= Clinical Presentation = | |||
* Monostotic FD usually presents by age 30. | * Monostotic FD usually presents by age 30. | ||
* Polyostotic FD presents in early childhood. | * Polyostotic FD presents in early childhood. | ||
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* Craniofacial involvement: Ethmoid (71%), Sphenoid (43%), Frontal (33%), etc. | * Craniofacial involvement: Ethmoid (71%), Sphenoid (43%), Frontal (33%), etc. | ||
= Diagnosis = | |||
[[File:Fibrous dysplasia.png|thumb]] | |||
* CT Imaging: Expansile remodeling of bone, ground-glass appearance. | * CT Imaging: Expansile remodeling of bone, ground-glass appearance. | ||
* MRI: For cranial nerve compression. | * MRI: For cranial nerve compression. | ||
* Histology: “Chinese figure” formation in bone trabeculae. | * Histology: “Chinese figure” formation in bone trabeculae. | ||
<br clear="all"> | |||
= | = Treatment = | ||
* Asymptomatic lesions: Conservative management. | * Asymptomatic lesions: Conservative management. | ||
* Medications: Alendronate (bone density), Denosumab (reduces pain but concerns over side effects). | * Medications: Alendronate (bone density), Denosumab (reduces pain but concerns over side effects). | ||
* Surgical options: Contouring, total resection, computer-based planning, timing for children. | * Surgical options: Contouring, total resection, computer-based planning, timing for children. | ||
== | == Considerations == | ||
* McCune-Albright syndrome management. | * McCune-Albright syndrome management. | ||
* Orbital apex involvement: Proptosis, diplopia, and options for optic nerve compression. | * Orbital apex involvement: Proptosis, diplopia, and options for optic nerve compression. | ||
* Malignant transformation: Rare | * Malignant transformation: Rare (0.4 to 4%). | ||
Latest revision as of 21:46, 2 March 2024
Introduction
- A benign fibro-osseous lesion of immature mesenchymal cells.
- Commonly affects long bones, ribs, and skull.
Pathophysiology
- Originates from mutated pluripotent embryonic cells leading to skeletal stem cells.
- Lesions form as cancellous bone is replaced with fibrous tissue and immature woven bone.
- Monostotic FD (70% of cases) vs. Polyostotic FD.
Genetic Basis and Related Syndromes
- Genetic mutation: Chromosome 20q13 at the GNAS1 locus.
- Constitutively active mutant of the α subunit of the G protein (Gsα).
- McCune-Albright syndrome: Characterized by polyostotic FD, endocrinopathy, café au lait spots.
Clinical Presentation
- Monostotic FD usually presents by age 30.
- Polyostotic FD presents in early childhood.
- Symptoms: Painless osseous expansion, facial asymmetry.
- Craniofacial involvement: Ethmoid (71%), Sphenoid (43%), Frontal (33%), etc.
Diagnosis
- CT Imaging: Expansile remodeling of bone, ground-glass appearance.
- MRI: For cranial nerve compression.
- Histology: “Chinese figure” formation in bone trabeculae.
Treatment
- Asymptomatic lesions: Conservative management.
- Medications: Alendronate (bone density), Denosumab (reduces pain but concerns over side effects).
- Surgical options: Contouring, total resection, computer-based planning, timing for children.
Considerations
- McCune-Albright syndrome management.
- Orbital apex involvement: Proptosis, diplopia, and options for optic nerve compression.
- Malignant transformation: Rare (0.4 to 4%).