Glioblastoma multiforme (GBM) is the most common form of primary malignant brain tumor in the central nervous system (CNS). While these tumors are commonly found in supratentorial areas, they rarely occur in infratentorial regions, accounting for approximately 0-3.4% of all primary GBMs. The occurrence of GBMs in adults is relatively rare, with even fewer cases reported in the elderly population. Typically, these tumors present as rapidly expanding lesions in the posterior fossa, often leading to increased intracranial pressure, cerebellar dysfunction, and perilesional edema. Although clinical presentation along with diagnostic imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) provide valuable insight into the diagnosis, they cannot definitively confirm the presence of GBM. This report describes the case of a 76-year-old female with a medical history of hypertension, depression, and dyslipidemia. The patient initially exhibited progressive symptoms, including ataxia, imbalance, and vertigo. CT scans revealed an infiltrative, intra-axial lesion located in the superior and middle parts of the vermis. MRI scans identified a heterogeneous mass in the superior and median vermian region of the cerebellum, with ring-like enhancement and a necrotic center. A suboccipital approach was used for surgical resection, specifically targeting the superior vermis. Intraoperative histological examination revealed the presence of a high-grade malignancy, which led to a subtotal resection. The final histological analysis confirmed the diagnosis of a grade IV astrocytoma according to the World Health Organization (WHO) classification. Following surgery, the patient commenced chemotherapy and radiotherapy four weeks post-operation. This case highlights the unusual location of the tumor, which is an unusual location for glioblastomas. Although posterior fossa lesions are relatively rare, they should be considered in the differential diagnosis of such tumors. However, metastatic lesions remain the most common cause of posterior fossa mass lesions, with a higher incidence than primary glioblastomas.
