Malignant meningiomas

Malignant
intraventricular meningioma with craniospinal dissemination and concurrent pulmonary metastasis. Primary MIVM and first local recurrence. (A) CT scan, showing a huge hyperdense mass lesion in the trigone with central necrosis. (B) MRI scan, demonstrating heterogeneous enhancement of the lesion. (C) Histopathological findings revealing anaplastic meningioma with cellular pleomorphism, nuclear atypia, and geographic necrosis (H & E 400×). (D) Postoperative MRI scan, displaying no residual tumor. (E) MRI scan, disclosing local recurrence. (F) MRI scan, showing a huge residual cavity after the second craniotomy.
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Malignant
intraventricular meningioma with craniospinal dissemination and concurrent pulmonary metastasis. Radiological imaging of intracranial and extracranial metastasis. (A) MRI scan, disclosing local recurrence and diffuse enhancement around the cavity walls. (B) Tumor invasion of the tentorium and transverse sinus was seen (arrow). (C) MRI scan, revealing an enhanced nodule with dural tail in the right temporal lobe. (D, E) Spinal MRI scan with contrast, displaying a small extramedullary-intradural lesion at the C2 level and numerous punctate nodules along the spine surface. (F) Thoracic CT scan, showing a large mass in the left lung.
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Cerebrospinal
fluid dissemination of anaplastic intraventricular meningioma: report of a case presenting with progressive brainstem dysfunction and multiple cranial nerve palsies. Brain MRI of the present patient at admission (a –c), and 17 days (d–f) and 40 days (g–i) after admission. Fluid attenuated inversion recovery (FLAIR) images at admission showed no gross abnormality, including in the brainstem and cranial nerves (a, b), although a mass-enhancing lesion was observed in the trigone of the left lateral ventricle on T1-weighted imaging (c). 17 days after admission, FLAIR images revealed slight hyperintensity in the exit for the trigeminal nerve and the left cerebellar hemisphere (d, e), and diffusion-weighted imaging (DWI) showed hyperintensity in the left cerebellar hemisphere (f). At the final MRI at 40 days after admission, diffuse high-intensity lesions and hydrocephalus were observed in the brainstem and cerebellum on FLAIR (g, h) and DWI revealed multiple hyperintense lesions in the bilateral cerebellar hemispheres (i)
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Anaplastic meningiomas (also known as malignant meningiomas) are uncommon, accounting for only ~1% of all meningiomas . Along with rhabdoid meningioma and papillary meningioma are considered WHO grade III tumors and demonstrate aggressive local growth and high recurrence rate.

It should be noted that epidemiology, clinical presentation and radiographic features do not reliably distinguish anaplastic meningiomas from benign meningiomas (WHO grade I) and atypical meningiomas (WHO grade II), and thus that content is unnecessarily repeated here. Generally, these tumors grow faster, have more heterogeneous/aggressive imaging appearances, and have a tendency to recur early.

Pathology

Anaplastic meningiomas are those with the following histological characteristics :

  • obvious malignant features similar to those seen in melanoma, carcinoma, or high-grade sarcoma
  • 20 or more mitosis per ten high-power fields

Radiographic features

Generally, it is not possible to confidently distinguish benign (WHO grade I) and atypical (WHO grade II) from anaplastic (WHO grade III) meningiomas on general morphology. The most reliable feature in suggesting a non-grade I tumor is the presence of lower ADC values (reflecting higher cellularity)  .

Importantly presence of vasogenic edema in adjacent brain parenchyma is not a predictor of atypical or anaplastic histology .

Brain invasion, although by definition denoting at least a grade II tumor, is also surprisingly difficult to predict on MRI.

Treatment and prognosis

First line therapy is surgical resection with radiotherapy (external beam or brachytherapy) often added both for complete and incomplete resections (see Simpson grade). Radiation has been shown to improve local control and prolongs overall survival .

No effective chemotherapeutic agents have been identified .

The recurrence rate is significantly higher (50-94%) than that seen in grade II meningiomas (29-52%) and this correlates with reduced survival .

Siehe auch:
Assoziationen und Differentialdiagnosen zu malignes Meningeom:
intraventrikuläres
Meningeom
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malignes
intraventrikuläres Meningeom
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