Gliosarcoma associated with bilateral hippocampal sclerosis in a cat presenting complex partial seizures with orofacial involvement: A case report.

Key Clinical Message: Gliosarcoma, a rare cerebral neoplasm, has not been linked to hippocampal changes in cats. We report a case of complex partial seizures with orofacial involvement, revealing gliosarcoma concurrent with bilateral hippocampal sclerosis.

Abstract: A 16-year-old neutered female domestic shorthair cat presented with acute inappetence, ataxia, disorientation, and vacant staring. Brain MRI revealed an ill-defined, round, intra-axial mass in the right piriform lobe, showing hyperintensity on T2W, T2-FLAIR, and T2*W, and hypointensity on T1W images. The lesion exhibited mass effect and contrast enhancement in its center. Bilateral hyperintensity on T2-FLAIR images and contrast enhancement were observed in the hippocampus. Brain histologic and immunohistochemical analysis revealed cerebral gliosarcoma with concurrent hippocampal sclerosis. Feline LGI1-antibody testing on the serum and/or CSF was not performed due to insufficient biomaterial. Although retrospective testing on brain tissue was considered, it ultimately proved unfeasible, preventing us from ruling out antibody-associated limbic encephalitis. In conclusion, cerebral gliosarcoma should be included in feline intracranial tumor differentials, warranting brain MRI and feline LGI1-antibody testing in cats showing complex partial seizures with orofacial involvement. In our case, the prognosis remained poor due to the presence of a high-grade glioma.