Recurrent Radiation-Induced Cavernous Malformation After Gamma Knife Stereotactic Radiosurgery for Brain Metastasis.

Cavernous malformations are a rare complication of radiation therapy reported most commonly as a late complication after cranial irradiation for pediatric malignancies. However, cavernous malformations after stereotactic radiosurgery in adult patients are not well characterized. We present a case of a 67-year-old female with metastatic breast cancer who received Gamma Knife stereotactic radiosurgery for brain metastases and developed a cavernous malformation at the site of a treated metastasis 30 months after treatment. She underwent resection and did well until 55 months later, when she developed symptomatic recurrence of cavernous malformation without evidence of tumor recurrence, requiring repeat resection. This represents the first reported case of radiation-induced cavernous malformation treated with stereotactic radiosurgery for brain metastases, who later developed a recurrence of the cavernous malformation. As patients with brain metastases are living longer and are increasingly treated with stereotactic radiosurgery, awareness of cavernous malformation as a potential complication and the risk of recurrence is critical to ensure appropriate diagnosis and management.