FIGURE 4.

Pathologic features of canine oligodendroglioma. (A) In high-grade oligodendroglioma, cells with large, deeply cleaved, folded, or irregular nuclei (arrows) with occasionally pronounced nuclear molding are present. (B) High-grade oligodendrogliomas contain variably robust peripheral foci of microvascular proliferation characterized by tortuous clusters of vessels lined by multiple layers of endothelial cells and pericytes. (C) High-grade oligodendrogliomas have areas of necrosis which in some cases have cellular palisading (arrow) along the margin of the necrotic area. (D) In high-grade oligodendrogliomas, not all regions of necrosis are rimmed by palisading neoplastic cells. (E) In some oligodendrogliomas that have otherwise typical morphology, neoplastic cells are arranged in a pattern that mimics that of ependymal pseudorosettes. (F) Oligodendrogliomas frequently contain moderate to abundant amounts of basophilic, myxoid matrix.