Histological characterization of an ependymoma in the fourth ventricle of a cat.

A tumour occupying the fourth ventricle in a 3-year-old cat was removed surgically and characterized as a tanycytic ependymoma on the basis of histological features of low cellularity, inconspicuous perivascular pseudorosettes and fascicular architecture. Immunohistochemical analysis of sections revealed that the neoplastic cells were immunoreactive for glial fibrillary acidic protein (GFAP), vimentin and S-100. The histological and immunohistochemical findings were similar to those of human tanycytic ependymoma, a subclassification of ependymoma not previously described in domestic species.