Histopathology of radiation necrosis with severe peritumoral edema after gamma knife radiosurgery for parasagittal meningioma. A report of two cases.
BACKGROUND
Gamma knife radiosurgery (GKS) has been an effective treatment for meningiomas. Nevertheless, it still has certain risks. We present 2 cases of parasagittal meningioma after GKS complicated with radiation necrosis and peritumoral edema. The results of histologic examination are discussed.


METHODS
Two cases of parasagittal meningioma received GKS. Symptomatic peritumoral edema developed 3-4 months after GKS. Both of them underwent surgical resection of their tumor afterwards. Histologic examination showed necrotic change inside the tumor and infiltration of inflammatory cells in both cases. Hyalinization of blood vessels was seen in the 2nd case. The patients had improvement of neurologic function after surgical resection. Imaging performed 3 months after surgical resection showed alleviation of brain edema.


CONCLUSIONS
After radiosurgery peritumoral edema tends to occur in meningiomas with a parasagittal position. Radiation necrosis, infiltration of inflammatory cells, and radiation injury to the vasculature causing hyalinization of blood vessels are suggested as the underlying histopathology.
Chen
Chien-hua
CH
Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan.
Shen
Chiung-chyi
CC
Sun
Ming-hsi
MH
Ho
William L
WL
Huang
Chuan-fu
CF
Kwan
Po-cheung
PC
D000328:Adult; D001929:Brain Edema / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008577:Meningeal Neoplasms / Q000473:pathology* / Q000601:surgery*; D008579:Meningioma / Q000473:pathology* / Q000601:surgery*; D008875:Middle Aged; D009336:Necrosis; D011832:Radiation Injuries / Q000473:pathology*; D016634:Radiosurgery / Q000009:adverse effects*