Title page for ETD etd-10192006-222408


Type of Document Master's Thesis
Author Higgins, Michael Anthony
URN etd-10192006-222408
Title Morphological and Immunocytochemical Investigation of Canine Oligodendrogliomas
Degree Master of Science
Department Biomedical and Veterinary Sciences
Advisory Committee
Advisor Name Title
Rossmeisl, John H. Jr. Committee Chair
Inzana, Karen D. Committee Member
Jortner, Bernard S. Committee Member
Robertson, John L. Committee Member
Keywords
  • EGFR
  • GFAP
  • Dog
  • Oligodendroglioma
  • Ki-67
Date of Defense 2006-10-06
Availability restricted
Abstract
Previous studies of human oligodendroglial neoplasms have demonstrated the diagnostic and prognostic values of histomorphologic features and immunocytochemical markers. Primary spontaneous canine intracranial tumors share many of the biologic behaviors and pathologic features of their human counterparts. The objectives of this study were to determine if associations existed between five histomorphologic features (mitoses, cellular atypia, necrosis, vascular hypertrophy, and vascular proliferation), and three immunocytochemical markers (GFAP, EGFR, and Ki-67 labeling index) and the degree of malignancy, as defined by WHO grading criteria, of 15 canine oligodendroglial tumors. Of the histomorphologic variables examined, mitoses and cellular atypia were significantly greater in Grade III oligodendrogliomas than in Grade II oligodendrogliomas (p = 0.002, and p = 0.004, respectively), but no differences were noted between these features and Grade II oligoastrocytomas and Grade II or Grade III oligodendrogliomas. No significant associations were found between GFAP or EGFR immunoreactivity and tumor type or grade. The median percentage of Ki-67 immunoreactivity was significantly different between all tumor types and grades (p < 0.05), and was significantly higher in Grade III oligodendrogliomas than in both oligoastrocytomas (p = 0.014) and Grade II oligodendrogliomas (p = 0.006). Results of this study indicate that although mitoses and cellular atypia are useful histomorphologic features for the differentiation of tumors with oligodendroglial phenotypes, none of the variables examined reliably distinguished mixed gliomas from oligodendrogliomas. The presence of GFAP immunoreactivity in all tumor types suggests that oligodendroglial tumors may arise from a common multipotential cellular lineage. Similar to what has been demonstrated in humans, the Ki-67 labeling index correlated well with the degree of malignancy in the tumors studied.

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