title: A grade IV glioblastoma with an oligodendroglial component (GBM-O) in a horse.
abstract: A 4-year-old Dutch warmblood mare was presented with a 10-month history of ataxia and proprioceptive deficits. Computed tomography defined a large, non-contrast enhancing mass in the left cerebral hemisphere. Necropsy examination revealed a tumour that effaced much of the piriform and temporal lobes. Microscopically the lesion was classified as a grade IV glioblastoma with an oligodendroglial component (GBM-O). The tumour was composed of highly pleomorphic cells organized in different patterns within a fibrillary stroma. There were multiple foci of necrosis. At the periphery of the tumour neoplastic oligodendroglioma-like cells were embedded in an extracellular mucinous matrix. Most neoplastic cells were strongly immunoreactive for glial fibrillary acidic protein; however, the oligodendroglioma cells did not express this marker. Cells forming microvascular proliferations were positively labelled for expression of factor VIII and smooth muscle actin. All neoplastic cells were negative for Neu-N and synaptophysin. The proliferation index was up to 5%. All neoplastic cells and normal brain tissue from the horse were uniformly negative for expression of epidermal growth factor receptor (EGFR), EGFR vIII mutant and the phosphatase and tensin homologue (PTEN) compared with positive control human GBM tissue. To our knowledge this is the first report of a GBM-O in the horse.
authors.affiliation: The William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, USA. bgericota@vmth.ucdavis.edu
authors.forename: B
authors.initials: B
authors.lastname: Gericota
authors.forename: M
authors.initials: M
authors.lastname: Aleman
authors.forename: T A
authors.initials: TA
authors.lastname: Kozikowski
authors.forename: P
authors.initials: P
authors.lastname: Pesavento
authors.forename: A W
authors.initials: AW
authors.lastname: Bollen
authors.forename: J E
authors.initials: JE
authors.lastname: Madigan
authors.forename: R J
authors.initials: RJ
authors.lastname: Higgins
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D050533:Glomerular Basement Membrane / Q000378:metabolism / Q000473:pathology; D006736:Horses / Q000235:genetics / Q000378:metabolism; D009336:Necrosis / Q000235:genetics; D009836:Oligodendroglia / Q000378:metabolism / Q000473:pathology; D009837:Oligodendroglioma / Q000235:genetics; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism
chemical_list: D005904:Glial Fibrillary Acidic Protein; C410723:epidermal growth factor receptor VIII; D066246:ErbB Receptors; D010744:Phosphoric Monoester Hydrolases