title: Locally aggressive fibrous dysplasia.
abstract: Although fibrous dysplasia (FD) is a benign fibro-osseous lesion, locally aggressive behaviour has rarely been described but is poorly characterised. In this study, we document clinical, radiological and pathological (including molecular genetics) findings in three cases of locally aggressive FD, two of which involved the ribs. Lesions in these cases, one of which was a recurrent lesion, were followed up for 2-7 years. All of the lesions showed typical histological features of FD but were characterised by extension through the bone cortex into the extra-osseous soft tissue. The lesions did not exhibit overexpression/amplification of CDK4 and MDM2; in two of the cases, a GNAS mutation was identified. Our findings confirm that FD can rarely exhibit locally aggressive behaviour with extension beyond the bone compartment into the surrounding soft tissue; these lesions can be distinguished from low-grade intramedullary osteosarcoma by lack of amplification/overexpression of CDK4 and MDM2 and the presence of a GNAS mutation.
authors.affiliation: Department of Histopathology, NDORMS, University of Oxford, Oxford, UK.
authors.forename: T G
authors.initials: TG
authors.lastname: Kashima
authors.forename: N M
authors.initials: NM
authors.lastname: Gamage
authors.forename: H
authors.initials: H
authors.lastname: Ye
authors.forename: M F
authors.initials: MF
authors.lastname: Amary
authors.forename: A M
authors.initials: AM
authors.lastname: Flanagan
authors.forename: S J
authors.initials: SJ
authors.lastname: Ostlere
authors.forename: N A
authors.initials: NA
authors.lastname: Athanasou
mesh_terms: D000328:Adult; D000368:Aged; D018797:Cell Cycle Proteins; D051358:Cyclin-Dependent Kinase 4 / Q000032:analysis; D005260:Female; D005357:Fibrous Dysplasia of Bone / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis; D014057:Tomography, X-Ray Computed
chemical_list: D018797:Cell Cycle Proteins; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4