title: Immunohistochemical features of giant cell ependymoma of the filum terminale with unusual clinical and radiological presentation.
abstract: BACKGROUND
  Giant cell ependymoma of the filum terminale is a rare variant, generally manifested as a well-circunscribed intradural mass with an indolent biological behavior.
  
  
  METHODS
  We describe the case of a 48-year-old Mexican female who non-relevant past medical history, that developed a GCE of the filum terminale. Magnetic resonance imaging and computed tomography revealed the presence of an intra-axial tumor extending from L3 to L5 with extra-medullary invasion. Therefore the tumor was considered unresectable and only incisional biopsy was obtained, establishing the tentative diagnosis of a poorly differentiated neoplasia. A second evaluation of the case revealed the presence of numerous non-cohesive pleomorphic giant cells with intranuclear inclusions and broad eosinophilic cytoplasm, alternating with intermediate size cells with round, hyperchromatic nuclei and forming a perivascular pseudo-rosettes pattern. The ependymal phenotype was supported by light microscopy and corroborated by immunohistochemistry analysis. The patient was subsequently treated with radiotherapy 54Gy. She is alive after a 27-month follow-up, with residual disease, difficulty ambulating and pain.
  
  
  CONCLUSIONS
  GCE of filum terminale may have an atypical clinical and radiological presentation, albeit with invasive characteristics and anaplasia on histologic analysis. However, its biological behavior is indolent and associated to longer survival. Due to the presence of giant cells, the differential diagnosis of other primary neoplasias at that site were considered, including paraganglioma, malignant peripheral nerve sheath tumors as well as metastatic malignant melanoma, adrenal carcinoma, thyroid gland carcinoma and urothelial carcinoma, that may all harbor giant cells.
authors.affiliation: Department of Pathology, Hospital de Oncologia, Centro Medico Nacional Siglo XXI, IMSS, Av Cuauhtemoc #330, Col: Doctores CP, 06720, Mexico City, Mexico. fernando.candanedog@incmnsz.mx.
authors.forename: Fernando
authors.identifier: http://orcid.org/0000-0002-6926-8182
authors.initials: F
authors.lastname: Candanedo-Gonzalez
authors.affiliation: Department of Radiotherapy, Hospital de Oncologia Centro Medico Nacional Siglo XXI, IMSS, Mexico City, Mexico.
authors.forename: Cindy Sharon
authors.initials: CS
authors.lastname: Ortiz-Arce
authors.affiliation: Department of Radiotherapy, Hospital de Oncologia Centro Medico Nacional Siglo XXI, IMSS, Mexico City, Mexico.
authors.forename: Samuel
authors.initials: S
authors.lastname: Rosales-Perez
authors.affiliation: Department of Radiology, Hospital de Oncologia Centro Medico Nacional Siglo XXI, IMSS, Mexico City, Mexico.
authors.forename: Ana Lilia
authors.initials: AL
authors.lastname: Remirez-Castellanos
authors.affiliation: Department of Pathology, Hospital de Oncologia, Centro Medico Nacional Siglo XXI, IMSS, Av Cuauhtemoc #330, Col: Doctores CP, 06720, Mexico City, Mexico.
authors.forename: Candelaria
authors.initials: C
authors.lastname: Cordova-Uscanga
authors.affiliation: Department of Pathology, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, Mexico.
authors.forename: Armando
authors.initials: A
authors.lastname: Gamboa-Dominguez
mesh_terms: D002420:Cauda Equina / Q000473:pathology*; D004806:Ependymoma / Q000473:pathology*; D005260:Female; D005870:Giant Cell Tumors / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010524:Peripheral Nervous System Neoplasms / Q000473:pathology*
keywords: Atypical clinical presentation; Ependymoma; Filum terminale; Giant cell; Immunohistochemistry markers