Cytologic and histologic features of spinal cord ependymoma in a young dog: a case report

A case of intramedullary ependymoma in a young dog is reported. A two year old dog was presented with paralysis of the forelimbs. At myelographic examination, an intramedullary pattern, blocking the progression of contrast medium, was observed. At necropsy, a 3 × 2 cm white-greyish mass was found extending from the 3 rd to 5 th lumbar levels. At cytological and histological examination, the mass was highly cellular and was comprised of ovoid cells with indistinct borders, elongated eosinophilic cytoplasm and round to oval vesicular nuclei. Cytoplasmic processes formed a fibrillar network wherein true rosettes and many pseudorosettes around a fibrovascular stroma were observed. Immunohistochemistry for vimentin and GFAP gave strong positive results in the neoplastic cells, especially around pseudorosettes and confirmed the diagnosis of intramedullary spinal ependymoma.