Fibro-osseous Lesions
Fibrous Dysplasia
Benign fibro-osseous lesion in which normal bone is replaced by cellular fibrous tissue with immature woven bone; due to GNAS mutation.
§ overviewOverview
Benign fibro-osseous lesion in which normal bone is replaced by cellular fibrous tissue with immature woven bone; due to GNAS mutation.
§ etiologyEtiology
- 01Post-zygotic activating mutation of GNAS gene (Gsα)
§ clinicalClinical Features
- 01Slow painless unilateral swelling
- 02Facial asymmetry
- 03Ill-defined margins on imaging
§ histopathHistopathology
- 01Cellular fibrous stroma with irregular 'Chinese-letter' woven bone trabeculae, no osteoblastic rimming
§ radiographicRadiographic Features
- 01Classic 'ground-glass' appearance
- 02Blends imperceptibly with normal bone
§ ctCT Findings
- 01Ground-glass matrix, cortical expansion, no periosteal reaction
§ classificationClassification
- 01Monostotic (70–80%)
- 02Polyostotic
- 03McCune–Albright syndrome (café-au-lait + endocrinopathies)
- 04Craniofacial FD
§ treatmentTreatment
- 01Observation for stable lesions
- 02Bisphosphonates for pain/rapid progression
- 03Cosmetic contouring after growth quiescence
§ complicationsComplications
- 01Optic nerve compression (craniofacial)
- 02Malignant transformation < 1%
§ prognosisPrognosis
Usually stabilises after skeletal maturity.
Draft — pending faculty review. Educational use only; verify against current guidelines and primary sources before clinical application.