Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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December 22, 2014
Radiation Necrosis with Delayed Cyst Formation
- Cyst formation is a well-known complication following gamma-knife radiosurgery (GRS) for treatment of intracranial arteriovenous malformations (AVMs). It has recently also been described following GRS of brain metastases.
- Patients with radiation-induced cyst formation present several years after GRS with neurological signs and symptoms, primarily headaches and seizures. These tumefactive cysts may also be found incidentally on follow-up imaging.
- Key Diagnostic Features
- Increasing cyst size at the site of the abnormality (tumor versus arteriovenous malformation)
- Gradual reduction in the size of the solid enhancing component of tumor/nidus of arteriovenous malformation
- Surrounding mass effect and edema can be seen.
- DDx:
- Tumor
- Infection
- Rx: Careful follow-up of these patients is crucial; and for asymptomatic patients close clinical observation is often sufficient. However, for a majority of patients symptoms are debilitating enough to require neurosurgical intervention, including cystoperitoneal shunt placement or cystectomy.
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