title: Extra-axial chordoma.
abstract: Chordomas are low-grade malignant tumors of bone that occur almost exclusively in the axial skeleton. Other neoplasms with a similar histologic picture but an extra-axial location have been described, including parachordoma, myxoid chondrosarcoma, and extra-axial chordoma. We herein present another case of the rare extra-axial chordoma. A 41-year-old woman developed an 8.3 cm mass in the pubic bone. The gross, microscopic, and immunohistochemical findings were identical to those of a classic chordoma. Parachordoma and myxoid chondrosarcoma were excluded from the differential diagnosis. Five previously reported cases of extra-axial chordoma were reviewed and found also to demonstrate clinical and pathologic features specific to chordoma, despite arising in an extra-axial location. Although rare, extra-axial chordoma does exist and should be recognized and managed in a similar fashion to its well-described counterpart. It must be differentiated from other histologic mimics, because the treatment and prognosis can differ significantly.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary, Alberta. lisa.difrancesco@cls.ab.ca
authors.forename: Lisa M
authors.initials: LM
authors.lastname: DiFrancesco
authors.forename: Cristobal A
authors.initials: CA
authors.lastname: Davanzo Castillo
authors.forename: Walley J
authors.initials: WJ
authors.lastname: Temple
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D001859:Bone Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D002817:Chordoma / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D011630:Pubic Bone / Q000473:pathology*; D018714:Radiotherapy, Adjuvant; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D014408:Biomarkers, Tumor