A 16-year-old female, with unremarkable medical and family history, presented with a huge dural-based mass in the right frontotemporal fossae, manifesting as headache. The patient underwent subtotal tumor resection. Intraoperative findings revealed focal erosion in the temporal fossa dura mater and skull adjacent to the lesion. Most of the tumor was located extraaxially, but a part of the tumor had invaded the temporal lobe, and had tightly adhered to the middle cerebral artery and its perforating vessels. Histological examination revealed cellular pleomorphism with mitotic activity, focal necrosis, but lacking endothelial proliferation, consistent with anaplastic pleomorphic xanthoastrocytoma (PXA) with component of anaplastic astrocytoma. Postoperatively, the patient underwent local irradiation and temozolomide administration, but the tumor relapsed 13 months later. Second tumor resection was performed followed by gamma knife radiosurgery, but the residual tumor progressively grew, extending into the contralateral hemisphere, and formed an enormous mass in the left frontal lobe at 17 months. Magnetic resonance imaging performed at 18 months revealed extracranial infiltration of the frontal tumor, through the cribriform plate, with enormous extension into the paranasal sinuses, nasal cavity, and orbit during the next month. The patient died at 20 months after the initial surgery. PXA with anaplastic appearance may have a component of anaplastic astrocytoma with more aggressive behavior.