Low-grade glial tumor with features of astroblastoma in a dog.

A 12-year-old, neutered, male Belgian Malinois/Great Dane cross dog presented with a 5-month history of weakness and lack of endurance followed by acute onset of rear limb ataxia. At autopsy, a 9 x 16 mm, multilobular, firm, white to tan, expansile mass was found in the cerebellum. Mild dilatation of the lateral ventricles was also noted. Histologically, there was a well-demarcated glial neoplasm composed of medium-sized astrocytic elements that had homogeneous cytoplasm, sometimes with globular eosinophilic inclusions, irregular peripherally located nuclei with a single nucleolus, and short cytoplasmic processes. Prominent perivascular pseudorosettes with cellular processes in contact with blood vessels were present. Some blood vessels exhibited hyalinized walls. Mitotic figures were not observed. Immunohistochemically, neoplastic cells expressed glial fibrillary acidic protein and vimentin. These features are consistent with an astroblastoma. This is the first clinicopathologic correlation and detailed description of a low-grade glial tumor with features of astroblastoma in a dog.