LAUSR

Gliosarcoma is characterized by the presence of alternating lesions of glial and mesenchymal components. Although many mesenchymal components have been reported, there are few reports on glial components. We here report two cases of gliosarcoma. Case 1 was a 42‐year‐old woman with right hemiparesis and motor aphasia. Magnetic resonance imaging (MRI) identified a tumor in the left frontal lobe. Pathological analysis of the tumor removal specimen revealed gliosarcoma, with a glial component resembling pleomorphic xanthoastrocytoma. Postoperatively, radiotherapy and chemotherapy were conducted, and the patient was symptom‐free over 12 months after surgery. Case 2 was a 67‐year‐old woman with a consciousness disorder and left hemiparesis. MRI revealed a tumor in the right frontal lobe. Pathological analysis of the first tumor removal specimen identified gliosarcoma, with a glial component characterized by large tumor cells. Additionally, the Ki‐67 labeling index of the glial component was greater than that of the mesenchymal component, and molecular genetic analysis disclosed a mutation in the telomerase reverse transcriptase (TERT) gene (TERT). Chemotherapy and radiotherapy were performed. Four months later, MRI revealed recurrence, and the second surgery was performed. Pathological analysis revealed giant cell glioblastoma without TERT mutation. The patient died due to tumor progression 12 months after the first surgery. It is essential to continue histopathological evaluation of glial components, and further genetic evaluation on gliosarcoma is required.