Radiation-induced tumor after stereotactic radiosurgery for an arteriovenous malformation: case report.

OBJECTIVE: To present a rare case of a radiation-induced malignancy after stereotactic radiosurgery. CLINICAL PRESENTATION: A 34-year-old woman presented with headaches. Imaging studies demonstrated a 4.5-cm arteriovenous malformation located in the pineal region. She was treated with a two-isocenter plan to a total dose of 1500 cGy prescribed to the 70% isodose line. She was lost to follow-up and presented with a change in mental status, nausea, headaches, and a generalized seizure 9 years later. Magnetic resonance imaging scans demonstrated a large, heterogeneously enhancing mass partially in the treatment volume. INTERVENTION: Surgical debulking demonstrated an infiltrating glial neoplasm consistent with a glioblastoma multiforme. There was no staining for epidermal growth factor receptor, whereas greater than 75% of nuclei stained positively with p53. CONCLUSION: The risk of radiation-induced tumors is currently unknown but needs to be determined to assess the risk-benefit profile for each patient.