We describe 2 cases of PXA with unusual clinical presentations and the case reports suggest that high Ki-67 LI in PXA can be used as a predictive marker of an adverse clinical course and that a combination of radiotherapy and chemotherapy with temozolomide may not be beneficial for patients with PXA with high Ki-67 LI values. The gene discussed is MKI67; the disease is pleomorphic xanthoastrocytoma.