title: Giant cell ependymoma of the filum terminale. A report of two cases.
abstract: We describe two histologically unusual cases of ependymoma of the filum terminale. Both tumors occurred in 14-year-old boys. An intradural encapsulated mass attached to the filum terminale was demonstrated radiologically in both cases and totally resected at surgery. In case 1 the neoplasm was uniformly composed of pleomorphic giant cells and was without perivascular pseudorosettes or myxopapillary changes. Case 2 was a myxopapillary ependymoma with multiple foci of pleomorphic giant cells. Neither tumor had prominent mitotic activity, necrosis, or endothelial proliferation. Both tumors were immunopositive for cytokeratin and glial fibrillary acidic protein. Ultrastructural features included basal laminae, interdigitating cell processes, microvilli, cilia, intercellular junctions, and cytoplasmic intermediate filaments. Cytogenetic analysis in case 1 showed a hypodiploid karyotype with monosomy of chromosomes 1, 10, 14, 16, 20, and 22. We interpret both tumors as most consistent with a variant of ependymoma. Because of the unique gigantocellular light microscopic appearance of the entire tumor in case 1, we propose classifying this tumor as a new morphologic subtype: giant cell ependymoma of the filum terminale. The combination of gigantocellular and myxopapillary features in case 2 supports a histogenetic relationship between giant cell ependymoma and myxopapillary ependymoma.
authors.affiliation: Department of Pathology (Neuropathology), Children's Hospital, Boston, MA 02115, USA.
authors.forename: N
authors.initials: N
authors.lastname: Zec
authors.forename: U
authors.initials: U
authors.lastname: De Girolami
authors.forename: D E
authors.initials: DE
authors.lastname: Schofield
authors.forename: R M
authors.initials: RM
authors.lastname: Scott
authors.forename: D C
authors.initials: DC
authors.lastname: Anthony
mesh_terms: D000293:Adolescent; D002420:Cauda Equina; D004806:Ependymoma / Q000378:metabolism / Q000473:pathology*; D015726:Giant Cells / Q000378:metabolism / Q000473:pathology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005910:Glioma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D008297:Male; D010524:Peripheral Nervous System Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D005904:Glial Fibrillary Acidic Protein; D007633:Keratins