title: Evidence of a polyclonal nature of myositis ossificans.
abstract: Myositis ossificans is a localized, self-limiting, reparative lesion that is composed of reactive hypercellular fibrous tissue and bone. Although it is clearly a benign lesion, its clinical, radiological, and histological appearance may sometimes mimic a malignant tumor. Whether myositis ossificans represents a monoclonal or polyclonal hyperplastic proliferation is not yet known. To address this question, we therefore extracted DNA from the respective paraffin-embedded tumor tissues of nine women with a median age of 50 years at diagnosis (range: 20-84 years) and studied the X inactivation pattern by means of methylation-sensitive polymerase chain reaction and primers that target the polymorphic CGG trinucleotide repeat of the FMR1 gene. The fact that we did not detect any skewing of the X inactivation pattern in the five successfully analyzed cases corroborates the notion that myositis ossificans results from a polyclonal proliferation and confirms that it is a reactive, reparative process. Analysis of the X inactivation pattern may, thus, supplement the differential diagnostic work-up of cases with an uncertain histology, at least in the informative proportion of female patients.
authors.affiliation: Department of Orthopedic Surgery, Medical University Graz, Graz, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Leithner
authors.forename: Andreas
authors.initials: A
authors.lastname: Weinhaeusel
authors.forename: Petra
authors.initials: P
authors.lastname: Zeitlhofer
authors.forename: Horst
authors.initials: H
authors.lastname: Koch
authors.forename: Roman
authors.initials: R
authors.lastname: Radl
authors.forename: Reinhard
authors.initials: R
authors.lastname: Windhager
authors.forename: Alfred
authors.initials: A
authors.lastname: Beham
authors.forename: Oskar A
authors.initials: OA
authors.lastname: Haas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049109:Cell Proliferation; D002999:Clone Cells / Q000473:pathology*; D019175:DNA Methylation; D003937:Diagnosis, Differential; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D008875:Middle Aged; D009221:Myositis Ossificans / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D012509:Sarcoma / Q000175:diagnosis; D012983:Soft Tissue Neoplasms / Q000175:diagnosis