title: Dedifferentiated chondrosarcoma mimicking a giant cell tumor. Is this low grade dedifferentiated chondrosarcoma?
abstract: We report a very rare case of a dedifferentiated chondrosarcoma mimicking a benign giant cell tumor. A 22-year-old male was admitted to our hospital with a history of mild left wrist pain after a skiing trauma. Radiology revealed an extensive meta-epiphyseal osteolytic lesion in the distal ulna, which appeared to be a giant cell tumor. Histological examination showed a biphasic tumor comprising chondroid and non-chondroid areas with a giant cell-rich lesion resembling a conventional giant cell tumor of the bone. Immunohistochemistry showed no expression of p16(INK4a), VEGFR1, KDR (VEGFR2), VEGFR3, cKIT, MDM2 or CDK4. However, high expression of the tyrosine kinases PDGFRA and PDGFRB was observed. Molecular analysis showed no amplification of the cMYC gene and no activating mutations in the cKIT (exons 9 and 11) or PDGFRA (exon 18) genes. He has been on follow-up for ten months, with no evidence of local recurrence or metastatic disease. In summary, this report highlights a very rare case of a dedifferentiated chondrosarcoma in which the dedifferentiated component of the tumor bears histologic resemblance to a conventional giant cell tumor of bone. We suggest that this tumor might be categorized in the group of low-grade dedifferentiated chondrosarcomas.
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-Universität (LMU), Munich, Germany. Electronic address: thomas.knoesel@med.uni-muenchen.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Knösel
authors.affiliation: Department of Pathology, Helios Hospital, Berlin, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Werner
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-Universität (LMU), Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Jung
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-Universität (LMU), Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kirchner
authors.affiliation: Orthopaedic Oncology, Department of Orthopaedic Surgery, Ludwig-Maximilians-University (LMU), Munich, Germany.
authors.forename: Hans Roland
authors.initials: HR
authors.lastname: Dürr
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics; D001859:Bone Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D054337:Cell Dedifferentiation; D002813:Chondrosarcoma / Q000201:enzymology / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D018212:Giant Cell Tumor of Bone / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008279:Magnetic Resonance Imaging; D008297:Male; D060787:Neoplasm Grading; D011237:Predictive Value of Tests; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014457:Ulna / Q000201:enzymology / Q000473:pathology* / Q000601:surgery; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor
keywords: Dedifferentiated chondrosarcoma; Giant cell tumor; Immunohistochemistry; Malignant potential; Mutational analysis