Abstract
A dark gray mass 3 cm in diameter replacing the right frontal cortex was found in the brain of a 5-year-old male Doberman Pinscher dog at necropsy. Microscopic studies revealed that the mass consisted of a proliferation of pleomorphic tumor cells: large bizarre or plump eosinophilic cells, multinucleated giant cells, and small lymphocytic cells. These neoplastic cells at the margin of the necrotic area had a psuedopalisade arrangement and tended to proliferate around blood vessels. Immunohistochemically, the tumor cells reacted intensely with the antibody for vimentin and moderately with those for S-100 and glial fibrillary acidic protein. This canine tumor is placed in the category of glioblastoma or undifferentiated astrocytoma, which is analogous to human giant cell glioblastoma.