Ependymoma in a filly

Abstract

The goal of this case report is a description of the clinical presentation and diagnosis of ependymoma in a Quarter Horse filly with neurological clinical signs. Macroscopic examination identified an irregular, reddish, gelatinous mass with infiltrative growth in the fourth ventricle and choroid plexus. Histopathological findings revealed the proliferation of moderately pleomorphic ependymal cells, which compressed and infiltrated the adjacent parenchyma. The cells presented a papillary arrangement forming single or multiple layers, sometimes organised in the form of rosettes with a central area filled with eosinophilic amorphous material. The cells were characterised by sparse, basophilic cytoplasm, round to ovoid nuclei, granular chromatin and inconspicuous nucleoli. Neoplastic cells were immunopositive for S-100 and vimentin. Macroscopic and microscopic findings are compatible with a final diagnosis of ependymoma. In young animals, although less frequently reported, neoplasia should be considered a differential diagnosis for animals presenting with neurologic signs.