The Pathological Change Of Meningioma After 9 Years Treated By Gamma Knife Radiosurgery: A Case ReportAli Liu1, Chung-cheng Wang1, Ke Dai1, Yi-lin Sun11Beijing Neurosurgical Institute, Beijing, China Keywords: meningioma, radiosurgery, gamma knife, neuropathology, outcome
It is the consensus of that radiosurgery for intracranial deep-seated small or residual meningiomas is safe and effective.
The long-term histopathological changes by such focused irradiation.
We present a patient, 64 year-old male, with a right tentorial meningioma. He had received craniotomy in another hospital six months before GKS.
The tumor was failed to be resected, and followed by gamma knife surgery for two times 7 months between. The tumor received 9Gy as a marginal dose at 28% isodose line in the first treatment, and 8 Gy marginal doses at 40% isodose covered in the second. The patient led a normal life and worked as usual after treatment. The follow-up images revealed the tumor well controlled, but five years after GKS, a cyst seen half around the tumor, then 9 years later, the cyst obviously enlarged. A craniotomy was required again, and a total removal of the tumor was performed.
During operation, the dural matter covering the tumor was found in tension. When the dura was cut open, the cerebrospinal fluid outflowed. There was no cyst found. The tumor was totally removed. An angiomatous meningioma was determined pathologically. Its central part of the radiolesion is replaced by hypocellular scar tissue under the light microscope. The marginal area (near the dura) shows that tumor cells still alive in various sizes with degeneration, and also some vascular cavernomas-like malformation. For the vasculopathy with subendothelial proliferation and hyaline degeneration resulted in lumina narrowed and loss of elasticity of the wall. Under the electron microscope, there are a lot of fragments of tumor cells necrobiosis and some marked degeneration with darker nucleoplasm and cytoplasm. The basement membranes of the vessels appear multilayer and diffusely thick. Occasionally, several desmosomes are revealed in the higher power field.
This is a retrospective study.
Gamma Knife radiosurgery does not promote anaplastic progression of this benign tumor.
We confirmed that a single high dose of radiation to control tumor growth was due to a combination of both cytotoxic and delayed vascular effects. The formation of the subarachnoid cyst may be related with the prior surgical damage of the brain tissue. Project Roles:
A. Liu (), C. Wang (), K. Dai (), Y. Sun ()