Neoplasms of the Meninges James G. Smirniotopoulos, MD

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Meningioma - Etiologic Factors • Trauma • Radiation • Viruses • Familial (Non-NF2) Meningioma • Neurofibromatosis – Type - 2 ‣ MISME Syndrome Meningioma - Radiation • Low Dose (2000 cGray = 2000 RADS) ‣ Used for Skull Base Tumors ‣ Pituitary Adenoma Meningioma - Molecular Biology • Postulate Tumor suppressor Gene • Chromosome 22 – deletion in tumor cells ‣ Both sporadic and inherited ‣ W/ or w/o NF-2 • Homozygous for TWO wild-type copies is normal • Heterozygous for 22 develops neoplasm ‣ Because there is a subsequent loss of the OTHER wild-type gene • Inherited (germline) deletion of 22 ‣ W/Schwannoma = NF2 Meningiomas • 1/7 to 1/4 of all Intracranial Primary ‣ ~ 6/ 100k / year ‣ Small ones in ~ 1.4% of autopsies • 1/4 – 1/3 of all Intraspinal Tumors • Middle age (40-60) • Female > Male ‣ Cranial 2-4:1 ‣ Spinal 4-8:1 ‣ Progesterone receptors in 2/3 ‣ Estrogen receptors less common Meningioma – Sharp Margin [Figure 2] • Wonton wrapper • Tortilla • Arepa (Colombia) • Sopapilla (Chile) • Bolo de milho (Brazil) • Pita (Greece and Middle East) • Naan (India) • Lavaash (Farsi/Iranian) • Injera (Ethiopia) Meningioma - CT Imaging • Non-Contrast ‣ Sharply Circumscribed ‣ Homogeneous ‣ Hyperdense (+/- Ca++) NOT from psammoma bodies ! ‣ Broad Dural Surface ‣ Bone Changes (Hyperostosis) • Enhanced CT ‣ Homogeneous Enhancement Meningioma – Early CT [Figure 3] Figure 3 A & B Meningioma – with classic features of hyperdensity and hyperostosis. Psammomatous Meningioma [Figure 4] Figure 2 A & B Meningioma – parasagittal. Meningioma - “En plaque” • En plaque (like a flat bread) • Pancake • Crepe Figure 4 A & B Spinal masses. Neuroradiology 1289 Neoplasms of the Meninges
Meningioma: Vasogenic Edema • VASCULAR ‣ Parasitization of MCA, etc. ‣ Compression of cortical aa./vv. • COMPRESSIVE TRAUMA • SECRETORY EFFECT • “TRANSCORTICAL FLOW” ‣ Close apposition of tumor to brain ‣ Thinned cortex ‣ +/- infiltration of brain ‣ Fluid gradient from meningioma into brain Meningioma and Edema [Figure 5] Figure 5 A, B & C Meningioma. WHO Grade 1 – benign, yet with extensive vasogenic edema. Meningioma and Edema Edema and Prognosis • Edema =/= Histology • Edema =/= Size • Edema ~ Pial Vascularity • Edema IS Related to Resectability ‣ Smaller “pseudocapsule” ‣ Surgical “cleavage plane” ‣ Tumor “sticks” to underlying brain • Resectability IS Related to Prognosis • Edema IS INDIRECTLY Related to Prognosis Meningiomas: MR Imaging • “Meningiomas are ISO-intense.” ‣ Usually on T1W ‣ Vary pulse sequence to see • EXTRA-axial Features ‣ Gray-matter buckling ‣ Pseudo-capsule of vessels ‣ Meningeal/dural “TAIL” • GADOLINIUM ENHANCEMENT Tentorial Meningioma [Figure 6] Meningioma: Peri-tumoral Edema • Male > Female (p = 0.026) • Hyperintense to GM on T2W (p = 0.016) • Pial blood supply (p = 0.001) ‣ Statistically significant • Pathology ‣ Grade 1: 23/79 cases had edema (32% G1) ‣ Grade 2-3: 7/79 had edema (87% G2- 3) Lee K, Joo W, Rha H, et al: Peritumoral brain edema in meningiomas … Surgical Neurology 2008;69:350-5. Figure 6 A & B Gross Courtesy Tom Naidich, Mt. Sinai, NY. Meningioma – Pre and Post Gd [Figure 7] Figure 7 A & B Frontal Meningioma - notice the bone thickening (hyperostosis) under the center of the lesion. Neoplasms of the Meninges 1290 Neuroradiology
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Neoplasms of the Meninges James G. Smirniotopoulos, MD

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