Anaplastic and meningothelial meningiomas in a single tumor: A "dedifferentiated meningioma"?

Meningioma transformation to glioblastoma following stereotactic radiosurgery: A case report and review of the literature

Background

Meningiomas are the most common primary intracranial tumor with increasing incidence. Stereotactic Radiosurgery Gamma Knife (SRS-GK) is a commonly used modality for neoadjuvant and adjuvant treatment of these tumors and is often necessary for long-term disease control, particularly for the World Health Organization grade II/III meningiomas. While there is strong evidence to support the use of SRS-GK for meningioma, there exists a risk of secondary malignancy that is not well understood. We report a case of glioblastoma (GBM) that arose near the bed of a meningioma previously treated with SRS-GK and discuss other cases of GBM that emerged at a site of meningioma reported in the literature.

Case Description

A 79-year-old female with a history of a blood-clotting disorder presented to the hospital with sudden facial sensory disturbances. On magnetic resonance imaging (MRI), a homogeneously enhancing lesion was observed in the right temporal lobe, consistent with a meningioma. Following 2 years of surveillance, the patient underwent SRS-GK for enlargement of the lesion. The patient later presented with headache and gait instability 12 years following SRS-GK. MRI revealed a large ring-enhancing lesion with surrounding edema histologically confirmed to be a GBM. At 9 months following initial tumor resection and a combination of radiotherapy and temozolomide, the patient was neurologically intact.

Conclusion

There is a very small risk of meningioma to GBM conversion following SRS. Although SRS-GK poses a risk of secondary malignancy, there are some reported cases that underwent malignant transformation without SRS-GK. This suggests that SRS-GK is not the only factor in transformation and is a reasonable therapeutic modality to consider utilizing. Patients and their families should be appropriately counseled on the potential risks of radiation therapy, even for benign lesions like a meningioma.

Atypical and Fibrous Meningioma with Differential Cerebral Blood Volume on Magnetic Resonance Imaging: A Case Report

Magnetic resonance imaging (MRI) features of meningiomas typically reveal a well-circumscribed and contrast-enhancing dural mass. Here we discuss the differences in MRI findings between typically benign and atypical meningioma, and their clinical implications. An MRI of a 67-year-old man revealed a substantial homogeneous enhancing tumor nodule. The MRI also showed two components in the tumor, and the regional cerebral blood volume (rCBV) was higher in the lateral than in the medial mass. A pathological examination also revealed features of both benign and atypical meningiomas. The Ki-67 labeling index was 1% on the medial side and 5% on the lateral side. There were clearly two components within the tumor mass, and the MRI revealed differential rCBV in the tumor. The results indicated a nontypical MRI of meningiomas, allowing for predictability of atypical meningiomas using MRI before surgical resection.

Double Meningioma: A Case of Two Fibrous Meningiomas Coexisting Isolatedly in Meningothelial Meningioma

Meningiomas are the most common intracranial primary neoplasm in adults, and show various histological subtypes, indicating heterogeneous clinical and molecular genetic characteristics. Different subtypes of meningioma coexisting independently within the main tumor of another different subtype is a quite rare clinical situation. A 69-year-old woman presented with a several- year history of dizziness as a non-specific complaint. Magnetic resonance imaging (MRI) revealed an extra-axial mass lesion in the left parieto-occipital region including two well-demarcated, round mass components. Total resection was performed via left parieto-occipital craniotomy. Two white masses were identified within the main tumor, with neither showing dural attachments. Pathological findings showed the main mass represented meningothelial meningioma and the demarcated mass lesions were both fibrous meningiomas. No transitional features existed between these subtypes. No differences in genetic characteristics were evident between subtypes of meningioma. We have described, apparently for the first time, a case of two fibrous meningiomas coexisting in an isolated manner in meningothelial meningioma with the similar molecular genetic profile.