Abstract
A 5-year-4-month-old neutered female French bulldog had a brain mass that was surgically excised. Histologically, the tumor consisted of neoplastic oligodendroglial and spindle-shaped cells, and chondroid tissues. Immunohistochemically, oligodendroglial cells were immunopositive for oligodendrocyte transcription factor 2 (OLIG2), 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), platelet-derived growth factor receptor alpha (PDGFRA), vimentin, cluster of differentiation 44 (CD44), and WW domain containing transcription regulator 1 (WWTR1). Spindle-shaped cells were immunopositive for OLIG2, vimentin, CD44, and WWTR1. In chondroid tissues, chondrocyte-like cells were immunopositive for OLIG2, PDGFRA, vimentin, and WWTR1. In the present case, the tumor had oligodendroglial features accompanied by mesenchymal and chondroid metaplasia. Based on these findings, the dog was diagnosed with an oligosarcoma with chondroid metaplasia.