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.
§ figuresFigures (5)
Fig. 1Medium power shot with the classic 'Chinese character' bone spicules.
“Bone FibrousDysplasia LP CTR” · Sarahkayb · CC BY-SA 4.0 · Wikimedia Commons
Fig. 2Immature bony trabeculae in a fibrous stroma.
“Bone FibrousDysplasia Jaw MP3 PA” · Sarahkayb · CC BY-SA 4.0 · Wikimedia Commons
Verified open-access images only, reproduced for education under their stated licences · no AI-generated or illustrative artwork · Fibrous Dysplasia figures pending faculty review.
§ 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.
§ evidenceReferences & Evidence
Current Classification
WHO Classification of Head and Neck Tumours
5th Edition — Volume 9
WHO Classification of Tumours Editorial Board · 2022
The authoritative international classification of head and neck, odontogenic and salivary gland tumours. Current terminology on this site follows this edition.
Evidence summary
Highest level of evidence linked to this page: WHO / Official Classification.
- L1 · Classification — 2
- L2 · Guideline — 1
- L6 · Textbook — 3
1 linked source was published from 2024 onwards. Where guidance is limited or contested, rely on the higher-level sources above rather than this summary. Educational use only — not a substitute for clinical judgement.
Content last reviewed
September 2026
Evidence last reviewed
September 2026
Next scheduled review
September 2027
Review status
EVIDENCE REVIEWED
Search latest PubMed evidence
Last literature search: 7 September 2026
Current Classification
WHO Classification of Tumours Editorial Board. IARC / World Health Organization · 2022
The authoritative international classification of head and neck, odontogenic and salivary gland tumours. Current terminology on this site follows this edition.
IARC / WHO. IARC · 2022
Continuously updated online edition of the WHO head and neck tumour classification.
Clinical Guidelines
Javaid MK, Boyce A, Appelman-Dijkstra N et al.. Orphanet journal of rare diseases · 2019 · 14(1):267
International consensus best-practice guidelines for fibrous dysplasia / McCune-Albright syndrome.
Histopathology References
Barnes L. CRC Press · 2008
Detailed histopathological reference for head and neck diagnostic criteria.
Textbook References
Neville BW, Damm DD, Allen CM et al.. Elsevier · 2024
Standard reference textbook of oral and maxillofacial pathology used throughout this atlas.
Rajendran R, Sivapathasundharam B. Elsevier · 2020
Undergraduate and postgraduate oral pathology textbook widely used in BDS and FCPS curricula.
Draft — pending faculty review. Educational use only; verify against current guidelines and primary sources before clinical application.