Reports of oligodendrogliomas in three white-tailed deer (Odocoileus virginianus)

Central nervous system tumors are rarely reported in cervids. The current report describes gross and histopathologic oligodendrogliomas in 3 white-tailed deer (Odocoileus virginianus), and selected immunohistochemical properties of 2 deer. All deer were euthanized due to central nervous system signs. Grossly, masses were variably circumscribed, locally invasive in the brain, light grey, and soft, and ranged from 2 to 5 cm in diameter. Histologically, tumors were characteristic for oligodendroglioma. The tumors were composed primarily of oval to round cells with round normochromatic to hyperchromatic nuclei, a pale granular cytoplasm, and well-delineated cytoplasmic membrane, and variable amounts of mucinous material, hemorrhage, and dystrophic mineralization. Immunohistochemistry, performed on masses from 2 deer, had positive cytoplasmic staining for S100 and variable staining on glial fibrillary acidic protein (1 deer negative and the other with rare positivity in astrocytes within the mass). This manuscript includes a discussion on the significance of these findings relative to central nervous system tumors of cervids and oligodendrogliomas from other species.