Papillary meningioma in the cerebellum of a cat

An unusual papillary meningioma in a cat with progressive cerebellar ataxia is described. Computed tomography revealed the presence of a primary tumour. Microscopically, the tumour was seen to arise from the cerebellar pia mater, forming perivascular structures composed of a single layer of cuboidal to columnar epithelial cells. By immunolabelling, the neoplastic cells appeared positive for cytokeratin, vimentin and S-100 protein. Ultrastructural examination, together with the immunocytochemical findings, indicated the mesenchymal and epithelial nature of the tumour.