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.