Ependymomas are rare glial tumors that typically arise from the ventricular ependymal tissue. Anaplastic ependymomas (WHO grade III) are the most aggressive and usually associated with poorer prognosis, particularly those with positive RELA fusion. Areas of cysts, hemorrhages or calcifications are common within these tumors. However, it is unusual to have a radiographic appearance mimicking arteriovenous malformation (AVM). Given its infrequent occurrence, early recognition, urgent neurosurgery consultation and tissue biopsy is crucial to ensure timely diagnosis and treatment.

67-year-old Caucasian male presents with subacute onset of confusion, headache and vomiting. He was last seen well 8 days prior to admission. One day prior to admission, patient developed nausea and vomiting. On the day of admission, he told his son on the phone that he was in New York and was locked at home. His son localized him by his phone company and found him at his house in Philadelphia. He appeared confused and was brought to the emergency department. CT brain and CT angiography revealed 1cm focal acute intraparenchymal hemorrhage within an AVM of right frontotemporal lobe with 6mm leftward midline shift. MRI brain with contrast showed 5.8 cm temporal lobe partially hemorrhagic, cystic and solid heterogeneously enhancing mass with abnormal signal within right lateral ventricle adjacent to the mass. Conventional angiography revealed a large hypervascular tumor in the right temporal region without evidence of AVM. Patient underwent gross total resection of the tumor and pathology revealed anaplastic ependymoma, WHO grade III, with focal clear cell changes. He received concurrent chemoradiation followed by adjuvant temozolomide. His symptoms improve postoperatively. 

This case illustrates that anaplastic ependymomas can be highly vascular and appear similar to vascular malformation. Recognition of this atypical radiographic feature of ependymomas with early neurosurgical intervention and tissue biopsy is critical for good neurological outcome.