TY - JOUR T1 - Tumefactive Cysts: A Delayed Complication following Radiosurgery for Cerebral Arterial Venous Malformations JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 1152 LP - 1157 VL - 26 IS - 5 AU - Whitney B. Edmister AU - John I. Lane AU - Julie R. Gilbertson AU - Robert D. Brown AU - Bruce E. Pollock Y1 - 2005/05/01 UR - http://www.ajnr.org/content/26/5/1152.abstract N2 - Summary: We report five cases of symptomatic delayed cyst formation after radiosurgery for intracranial arterial venous malformations. Median time to discovery of the cysts following most recent radiosurgery was 59 months (range, 34–89 months). In all five patients, the radiation therapy–induced cysts exhibited tumefactive characteristics, including vasogenic edema, mass effect, and nodular enhancement. Despite these malignant features, these cystic lesions should be recognized as a benign complication of radiosurgery so that proper treatment (i.e., cystoperitoneal shunt surgery or excision) can be initiated. ER -