In this case report, we describe a rare case of a 32-year-old man who presented a highly aggressive, fast growing anaplastic oligodendroglioma five years after being treated with whole brain radiotherapy for a CNS recurrence of a lymphoblastic lymphoma. Initially, the patient was submitted to a surgical intervention and partial tumor resection, which allowed us to establish the pathologic diagnosis and the presence of a 1p deletion. Shortly after the operation the tumor grew back, exerting important mass effect. Since no radiation therapy or surgery could be used and the patient faced a critical condition, chemotherapy was started with a combination of temozolomide and bevacizumab. Immediately after the first cycle a marked clinical and radiological improvement was documented.