Fact-sheet: Meningioma of brain
Updated on 08/23/2017 at 6:45 AM
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Definition
Most common extra-axial tumor (15-18% of adult brain tumors), arising from meningothelial cells.
Clinical features
SETTING:
- Preferentially affects women over 45 years of age. Exceptional in children and adolescents (except in NF2).
- Predisposing factors:
- Genetic: NF2
- Radiotherapy (multiple, atypical meningiomas, occurring >10 years after RT)
- Hormonal factors
CLINICAL PRESENTATION:
- Asymptomatic (incidental finding ++)
- Depends on location and size: elevated ICP, sensorimotor deficit, seizures
CT
GENERAL SEMIOLOGY:
- extra-axial lesion
- well-defined
- iso- or hyperdense on unenhanced imaging (fibroblastic, transitional, and psammomatous forms are the most dense)
- calcifications in 20% of cases (grade I ++)
- intense and homogeneous enhancement after injection with a dural attachment (comet-tail sign)
- bone abnormality: hyperostosis, endostosis. If lysis and thinning: aggressive forms.
SIGNS OF BENIGNITY:
- Hyperostosis
- Calcification
SIGNS OF AGGRESSIVENESS:
- Bone lysis +++
- Lobulated or irregular contours
- Sharply demarcated intratumoral necrosis
- Significant perilesional edema
MRI
- extra-axial lesion
- isointense or slightly hypointense on T1, T2, and FLAIR, approximately 50% are isointense and 50% hyperintense relative to the cerebral cortex
- dilated feeding arteries with a radial arrangement
- intense and homogeneous enhancement after injection with a dural attachment
- perilesional edema in 50% of cases (++ in angiomatous forms).
- variable ADC, often elevated; if atypical or aggressive: diffusion hyperintensity with decreased ADC
- Perfusion: hyperperfusion (rCBV = 6-9) without return to baseline (absence of BBB and significant extracapillary leakage of contrast agent)
- Spectroscopy: classic tumor profile (choline and myoinositol peak, increased Cho/Cr and Cho/NAA ratios) + alanine peak (inconstant)
Vascular intervention
Diagnostic cerebral X-Ray Angiography +/- preoperative embolization if highly vascular.
Management
- Surgery +/- embolization
- Radiotherapy if sphenocavernous or recurrent meningioma, postoperatively if grade II or III
Classification
3 GRADES ACCORDING TO WHO, of increasing evolutivity:
- Grade I: meningothelial, fibroblastic, angiomatous, psammomatous, microcystic, secretory, transitional
- Grade II: atypical, clear cell, chordoid
- Grade III: anaplastic or malignant, rhabdoid, papillary
The histological criteria defining an anaplastic meningioma are:
- the presence of at least 20 mitoses per 10 high-power fields
- and/or a histological appearance of frank malignancy suggestive of carcinoma, malignant melanoma, or high-grade sarcoma.
--> Grade II and III: aggressive tumors with a high recurrence rate
Differential diagnosis
- Hemangiopericytoma (no calcifications, no hyperostosis)
- Solitary fibrous tumor (rare calcifications)
- Dural or leptomeningeal metastasis (rCBV = 1-3 unless metastasis from Kidney cancer or melanoma where rCBV is comparable to that of meningiomas)
- Dural lymphoma (no hyperperfusion)