Résumé : INTRODUCTION: Pleomorphic xanthoastrocytoma (PXA) is a rare brain glial tumour found in young patients. Most cases are reported as evolving low-grade neoplasms associated with a long survival after complete surgical resection. Some PXAs, however, can demonstrate secondary malignant transformation or progress with a short survival. Anaplastic histological features at first presentation or secondary meningeal dissemination have rarely been reported. CASE REPORT: We describe the case of a cerebral PXA in a 7-year-old girl presenting with anaplastic histological features and craniospinal meningeal dissemination that progressed rapidly with a poor outcome.