title: Dedifferentiated parosteal osteosarcoma with high-grade osteoclast-rich osteogenic sarcoma at presentation.
abstract: We report a case of a 32-year-old woman who presented with parosteal osteosarcoma of the distal femur with simultaneous dedifferentiation to a high-grade osteoclast-rich osteogenic sarcoma. This pattern of dedifferentiation is rare, particularly at the time of presentation. We are aware of three other somewhat comparable cases in the literature; however, none is quite similar to our case.
authors.affiliation: Department of Pathology, St. Joseph's Hospital, McMaster University, Hamilton, Ontario, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Shuhaibar
authors.forename: L
authors.initials: L
authors.lastname: Friedman
mesh_terms: D000328:Adult; D001706:Biopsy; D003131:Combined Modality Therapy; D005260:Female; D005266:Femoral Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008175:Lung Neoplasms / Q000556:secondary; D008279:Magnetic Resonance Imaging; D016609:Neoplasms, Second Primary / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D010010:Osteoclasts / Q000473:pathology*; D012516:Osteosarcoma / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D018217:Osteosarcoma, Juxtacortical / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D011859:Radiography