Gliosarcoma of the right cerebellar hemisphere and parahippocampal region: A case report and literature review.

Intracranial gliosarcoma (GSM) is a rare and aggressive variant of glioblastoma, characterized by a dismal prognosis and high rates of early recurrence and metastasis. Preoperative differentiation from other neoplasms based on imaging features remains a significant clinical challenge. The current study reports the case of a 55-year-old female who presented with a headache as the primary clinical symptom. The patient underwent brain MRI due to progressively worsening symptoms of diplopia, intermittent dull headaches localized to the right occipital region and an unsteady gait. Preoperative magnetic resonance imaging revealed a large, lobulated mass in the right cerebellar hemisphere extending into the parahippocampal region. The diagnosis of WHO Grade IV GSM was confirmed by postoperative histopathological and immunohistochemical analysis, which revealed a biphasic pattern with glial fibrillary acidic protein-positive glial and smooth muscle actin/vimentin-positive sarcomatous components, alongside a high Ki-67 proliferation index of 30%. The patient underwent a subtotal resection followed by adjuvant radiotherapy with concurrent temozolomide chemotherapy. Despite this multimodal treatment, follow-up imaging demonstrated tumor recurrence at 2 months, with significant further progression and brain herniation observed at the 12-month follow-up. The present case underscores the diagnostic challenges and aggressive clinical course of GSM, particularly when located in the cerebellum. The rapid recurrence despite combined-modality therapy highlights the need for improved diagnostic strategies and more effective treatment protocols for this formidable disease.