title: Well-differentiated extraskeletal osteosarcoma: report of 2 cases, 1 with dedifferentiation.
abstract: Extraskeletal osteosarcoma (ESOS) is a rare soft tissue sarcoma, typically characterized by high-grade histological features and a grave prognosis. However, 4 cases of well-differentiated ESOS with a better prognosis have been documented in the literature within the last 40 years. We report 2 additional cases, 1 with multicentric presentation and dedifferentiation, and we emphasize the histological features that are useful in distinguishing this lesion from other soft tissue tumors. Well-differentiated ESOS seems to represent a rare but distinct low-grade variant of ESOS. The limited published experience suggests that although the biologic behavior of this tumor is better than that of classical ESOS, there are cases with progression to a higher grade, leading eventually to final demise.
authors.affiliation: Department of Pathology, Hospital for Joint Diseases, New York, NY 10003, USA. luigia52@yahoo.com
authors.forename: Luigia C
authors.initials: LC
authors.lastname: Abramovici
authors.forename: Prodromos
authors.initials: P
authors.lastname: Hytiroglou
authors.forename: Robert M
authors.initials: RM
authors.lastname: Klein
authors.forename: Georgios
authors.initials: G
authors.lastname: Karkavelas
authors.forename: Antonios
authors.initials: A
authors.lastname: Drevelegas
authors.forename: Eugenia
authors.initials: E
authors.lastname: Panousi
authors.forename: German C
authors.initials: GC
authors.lastname: Steiner
mesh_terms: D000328:Adult; D001415:Back; D002454:Cell Differentiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009362:Neoplasm Metastasis; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D013848:Thigh; D014057:Tomography, X-Ray Computed