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Meningioma


KEY FACTS

Terminology

  • Typical (“benign”) meningioma = WHO grade I

Imaging

  • Location

    • Supratentorial (90%)

      • –

        Parasagittal/convexity (45%), sphenoid (15-20%)

      • –

        Olfactory groove (5-10%), parasellar (5-10%)

    • Infratentorial (8-10%) (CPA most common site)

    • Multiple meningiomas in 1-9% of cases

  • General features

    • Extraaxial mass with broad-based dural attachment

    • > 90% enhance homogeneously, intensely

  • CT

    • Hyper- (70-75%), iso- (25%), hypodense (1-5%)

    • Hyperostosis, irregular cortex, ↑ vascular markings

    • Ca++ (20-25%) (diffuse, focal, sand-like, “sunburst,” globular, rim)

    • Necrosis, cysts common; hemorrhage rare

  • MR

    • Look for CSF/vascular “cleft” between tumor, brain; dural “tail” (35-80% but nonspecific)

  • Correlation between imaging, ↑ tumor grade

    • Indistinct tumor-brain interface

    • Capsular enhancement

    • Heterogeneous tumor enhancement

Top Differential Diagnoses

  • Dural metastasis

  • Granuloma (TB, sarcoid)

  • Idiopathic hypertrophic pachymeningitis

  • Extramedullary hematopoiesis

  • Hemangioma, dura/venous sinuses

Clinical Issues

  • Most common adult primary intracranial neoplasm (20-35%); peak age = 40-60 years (rare in children unless NF2); often asymptomatic, incidentally found, grow slowly

Coronal graphic depicts classic meningioma with broad base toward dura with reactive dural tail
. Note the CSF-vascular cleft
between invaginating tumor and brain. Typical “sunburst” of dural vessels
(in this case, the middle meningeal artery) supplies center of lesion, whereas pial vessels supply periphery.

Axial T2 FS MR in a 59-year-old man with headaches shows a moderately hyperintense extraaxial mass
with “sunburst” of vessels (flow voids) supplying center of tumor
.

Axial T1 C+ MR in the same patient shows that the mass
enhances strongly and uniformly.

Coronal T1 C+ MR shows the enhancing mass
with slightly more intensely enhancing dural tail
. A WHO grade I meningioma was removed at surgery. The dural tail was not involved by tumor.

TERMINOLOGY

Abbreviations

  • Typical meningioma (TM)

  • Atypical meningioma (AM), malignant meningioma (MM)

Definitions

  • TM = WHO grade 1 meningioma

IMAGING

General Features

  • Best diagnostic clue

    • Dural-based enhancing mass → cortical buckling, trapped CSF/vessels in “cleft” between tumor and brain

  • Location

    • Supratentorial (90%)

      • –

        Parasagittal/convexity (45%), sphenoid ridge (15-20%)

      • –

        Olfactory groove (5-10%), parasellar (5-10%)

      • –

        Other (5%): Intraventricular, optic nerve sheath (ONSM), pineal region

      • –

        Rare: Intraparenchymal without dural attachment

    • Infratentorial (8-10%): CPA most common

    • Extradural (mostly intraosseous, calvaria) > 2%

    • Extracranial (head/neck)

      • –

        Most common: Paranasal sinuses

      • –

        Less common: Nasal cavity, parotid, skin

    • Multiple meningiomas: Seen in 1-9% of cases

      • –

        16% at autopsy (M < F)

  • Morphology

    • Extraaxial mass with broad-based dural attachment

CT Findings

  • NECT

    • Sharply circumscribed smooth mass abutting dura

      • –

        Hyperdense (70-75%), isodense (25%)

        • □

          Hypodense (1-5%), fat density (rare lipoblastic subtype)

      • –

        Calcified (20-25%)

        • □

          Can be diffuse, focal, sand-like (“psammomatous”)

        • □

          “Sunburst,” globular, rim patterns

        • □

          Calcification correlates with slow growth in asymptomatic meningiomas

      • –

        Necrosis, cysts, hemorrhage (8-23%)

    • Trapped CSF pools, cysts in adjacent brain common

    • Peritumoral hypodense vasogenic edema (60%)

    • Bone CT

      • –

        Hyperostosis, irregular cortex, ↑ vascular markings

  • CECT

    • > 90% enhance homogeneously, intensely

  • CTA

    • May be helpful prior to DSA, embolization

    • Delineates arterial supply, venous drainage

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