fibrous dysplasia
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Fibrous dysplasia is a skeletal developmental anomaly of the bone-forming mesenchyme that manifests as a defect in osteoblastic differentiation and maturation. Virtually any bone in the body can be affected. It is a nonhereditary disorder of unknown cause.
The nature of fibrous dysplasia is controversial. Non-random X-chromosome inactivation is indicative of a monoclonal pattern. It demonstrates a clonal origin for fibrous dysplasia, suggesting that the disease is a neoplastic lesion rather than a "dysplastic" process (14576938).
Synopsis
medullary bone replaced by fibrous tissue (radiolucent with the classically described ground-glass appearance)
trabeculae of woven bone contain fluid-filled cysts embedded largely in collagenous fibrous matrix
Types
monostotic form
polyostotic form
craniofacial form
Variants
fibrous dysplasia with cartilaginous differentiation ("fibrocartilaginous dysplasia") (8352377)
cemento-ossifying fibroma (7793475)
fibrous dysplasia protuberans (7959669)
osteofibrous dysplasia
Associations
malignant fibrous histiocytoma (11862471)
tuberous sclerosis (12748080)
Genetic forms
sporadic fibrous dysplasia
familial fibrous dysplasia
McCune-Albright syndrome or polyostotic fibrous dysplasia (PFD, PFOD) (MIM.174800) (activating mutations in GNAS1 gene)
Localization
craniofacial fibrous dysplasia
- gnathic fibrous dysplasia
extra-gnathic fibrous dysplasia
Cytogenetics
Molecular biology
monoclonality assessed (14576938)
activating somatic mutations of the GNAS1 (Gs alpha) gene (80-90%) (8541861, 17493233)
- GNAS1 encodes the alpha-subunit of the stimulatory G protein of adenylyl cyclase)
Differential diagnosis
See also
cherubism
benign fibro-osseous lesions of bone
References
Idowu BD, Al-Adnani M, O?Donnell P, Yu L, Odell E, Diss T, Gale RE, Flanagan AM. A sensitive mutation-specific screening technique for GNAS1 mutations in cases of fibrous dysplasia: the first report of a codon 227 mutation in bone. Histopathology. 2007 May;50(6):691-704. PMID: 17493233
Mikami M, Koizumi H, Ishii M, Nakajima H. The identification of monoclonality in fibrous dysplasia by methylation-specific polymerase chain reaction for the human androgen receptor gene. Virchows Arch. 2004 Jan;444(1):56-60. PMID: 14576938
Maki M, Saitoh K, Horiuchi H, Morohoshi T, Fukayama M, Machinami R. Comparative study of fibrous dysplasia and osteofibrous dysplasia: histopathological, immunohistochemical, argyrophilic nucleolar organizer region and DNA ploidy analysis. Pathol Int. 2001 Aug;51(8):603-11. PMID: 11564214
Voytek TM, Ro JY, Edeiken J, Ayala AG. Fibrous dysplasia and cemento-ossifying fibroma. A histologic spectrum. Am J Surg Pathol. 1995 Jul;19(7):775-81. PMID: 7793475