Malignant transformation of low-grade meningioma to high-grade gliosarcoma, six years after gamma knife radiosurgery

Leon Liem1, Brita Cheng2

1Honolulu, United States 2University of Hawaii, John A. Burns School of Medicine, Honolulu, HI

Keywords: meningioma, radiation-associated tumor, gamma knife, complications, glioblastoma multiforme

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     Gliosarcoma is a rare variant of glioblastoma multiforme. Radiation-induced gliosarcoma is rare having been reported in few patients, usually involving high radiation dosages for treatment of a primary malignancy. 
     Here we report a case in which a patient received single fraction gamma knife radiosurgery for a confirmed low-grade meningioma and subsequently developed a gliosarcoma six years later.
     A 50-year-old female presents with progressive confusion, expressive aphasia, right-sided weakness and ataxia. MRI imaging revealed a very large enhancing mass involving the left lateral ventricle and adjacent temporal lobe with extension into the quadrigeminal plate region. The patient underwent a left parietal craniotomy and a subtotal resection with residual tumor close to the brainstem. Pathology revealed a well-differentiated meningioma (WHO grade I). The patient received postoperative gamma knife radiosurgery to the residual tumor (14 Gy to the 50% isodose line, tumor volume 3.4cc with 100% coverage). Yearly MRI imaging revealed stable tumor size with no new symptomatology.
     Six years after initial presentation, the patient developed gradual reoccurrence of prior symptoms and new onset diplopia. MRI imaging revealed an interval increase in tumor mass size with superior and inferior extension on the left side of the tentorium, suggestive of recurrent meningioma. The patient underwent a left temporoparietal craniotomy and a subtotal resection with residual infratentorial tumor. Pathology revealed gliosarcoma (WHO Grade IV) and residual meningioma with radiation-induced changes. The patient declined neurologically and expired 8 months after symptom reoccurrence despite aggressive treatments.
     This was a single patient report.
     Although radiation induced malignancies are well documented, the induction of malignant tumors after gamma knife radiosurgery is extremely rare. 
     This case of the development of a gliosarcoma after gamma knife radiosurgery for meningioma points out that malignant transformation is a rare but real concern in the treatment of benign disease.


Project Roles:

L. Liem (), B. Cheng ()