Pleomorphic xanthoastrocytoma (PXA) is a rare primary astrocytic tumour of the nervous system usually involving the superficial temporal cortex of children and young adults. Although the tumour may exhibit histological features of pleomorphism or cellular atypia, the overall prognosis is good compared with other glial tumours, with only 30% of PXA recurring and 20% undergoing anaplastic transformation. Increased mitotic activity, high MIB-1 and proliferating cell nuclear antigen labelling indices and necrosis are poor prognostic factors, whereas abundant lymphocytic infiltration is associated with more benign biological behaviour. Rarely, in older patients, PXA may have a poor prognosis as these patients tend to have intracranial hypertension and focal deficits, as well as histological features of mitosis, increased cellularity and necrosis. We report the case of a 76-year-old woman who presented with dysphasia and right hemiparesis. A left fronto-temporal lobe PXA was misdiagnosed as glioblastoma multiforme. Although a rare and benign tumour type, PXA in the elderly tend to be more malignant, may have the radiological appearance of a malignant tumour and have poor prognosis.