meningiomas dr david cuenca

8/14/2019 Meningiomas Dr David Cuenca

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MENINGIOMAS

J. DAVID CUENCA RIVAS. MDNEUROSURGERY


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Definition

Meningothelial (arachnoidal) cell neoplasms,

typically attached to the inner surface of thedura mater.


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G rading

Most meningiomas are benign andcorrespond to WHO grade I.Certain histological subtypes or meningiomaswith specific combinations of morphologicparameters are associated with less

favourable clinical outcomes and correspondto WHO grades II (atypical) and III (anaplasticor malignant).


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I II III IV


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Incidence

Meningiomas account for about 24 30% of

primary intracranial tumours occurring in theUSA {305, 359}, with an annual incidence rateof up to 13 per 100 000 population in Italy{381}.


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Age and sex distribution

Meningiomas occur most commonly in middle-aged and elderly patients, with a peak during thesixth and seventh decades. Nonetheless, theyalso occur in children and the elderly. Childhoodexamples tend to include more aggressive forms

of meningioma. Among middle-aged patients,there is a marked female bias, the female:maleratio being approximately 1.7:1


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Etiology

Meningiomas are known to be induced by

low-, moderate-, and high-dose radiation, withan average time interval to tumourappearance of 35, 26 and 19 24 years,respectively.


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The role of sex hormones in the genesis of

meningiomas is less clear.


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Localization

The vast majority of meningiomas arise in

intracranial, intraspinal or orbital locations.Intraventricular and epidural examples areuncommon.Rare meningiomas have been reported inalmost all organs.


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Localization

Within the cranial cavity, most meningiomas

occur over the cerebral convexities, oftenparasagittal in association with the falx andvenous sinus.


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Localization

Other common sites include the olfactory

grooves, sphenoid ridges, para/suprasellarregions, optic nerve sheath, petrous ridges,tentorium and posterior fossa.Most spinal meningiomas occur in thethoracic region.


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Localization

Atypical and anaplastic meningiomas most

commonly affect the falx and the lateralconvexities.


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SYMPTOMS AND SIGNS

Clinical features


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Symptoms and signs

Meningiomas are generally slowly growing

and produce neurological signs and symptomsby compression of adjacent structures;specific deficits depend upon the location of the tumour.


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Symptoms and signs

Headache and seizures often herald the

presence of a meningioma.


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Neur oimaging

On MRI,meningiomas

are typicallyisodense,contrast-enhancingdural masses.


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Neur oimaging

Some, like microcystic meningiomas, may

show little enhancement on CT

and MRI


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Neur oimaging

Calcification is best seen on C T scan.

A characteristic feature of meningiomas is theso-called dural tail surrounding the duralperimeter of the mass.


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Neur oimaging

P eritumoural cerebraledema is occasionallyprominent, particularlyaround atypical oranaplastic examples.


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Neur oimaging

It has also been described in association with

the secretory variant and in meningothelialtumours with so-called pericyte accumulationabout vessels.


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Macroscopy

Most meningiomas arerubbery or firm, well-demarcated, sometimeslobulated, roundedmasses that featurebroad dural attachment.


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Macroscopy

Invasion of underlyingdura or of dural sinuses isquite common.Occasional meningiomasinvade through dura toinvolve the skull, wherethey may inducecharacteristic

hyperostosis: such bonychanges are highlyindicative of skullinvasion.


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Macroscopy

Meningiomas mayattach to or encasecerebral arteries, butonly rarely do theyinfiltrate arterial walls.


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Macroscopy

They may also infiltratethe skin and extend toextracranialcompartments, such asthe orbit.


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Macroscopy

In certain sites,particularly along thesphenoid wing,meningiomas may growas a flat, carpet-likemass, a pattern termed

en plaquemeningioma.


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H istopathology

Of the subtypes in the WHO classification,

meningothelial, fibrous and transitionalmeningiomas are the most common.


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H istopathology Like normal arachnoidal cap cells, thetumour cells are largely uniform,

with oval nuclei with delicatechromatin that on occasion showcentral clearing, or the formulationof cytoplasmic-nuclear inclusions.

Meningothelial meningioma

In this classic and commonvariant, tumour cells formlobules, some partly

demarcated by thincollagenous septae.

Whorls and psammomabodies are not common inmeningothelialmeningioma


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H istopathology The tumour cells of fibrousmeningioma form wide fascicles,

with varying amounts of intercellularcollagen.F ibrous (fibroblastic)meningioma.

Consists of spindle cells

forming parallel, storiformand interlacing bundles ina collagen-rich matrix.

Nuclear featurescharacteristic of meningothelialmeningioma are oftenfound focally as well.


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H istopathologyVaguely lobular and fasciculararrangements often appear side by

side in association with conspicuoustight whorls and psammoma bodies.Transitional (mixed)meningioma.T hese common tumoursfeature the coexistence of meningothelial and fibrouspatterns as well as transitionsbetween these patters.


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H istopathology

The differential diagnosis includes vascular malformationsand capillary haemangioblastoma, depending on theprominence of vessels and the occasionally nonMeningothelial appearance of the tumour cells.

Angiomatous meningiomas do not exhibit aggressive behaviour.Adjacent cerebral edema may be out of proportion to tumoursize.

Angiomatous meningiomaP redominance of bloodvessels over that of thetumour cells. The vascularchannels may be small- or

medium-sized, thinwalledor thick.


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H istopathology

P leomorphic cells may be numerous, but microcystic meningiomas are typicallybenign. Like the angiomatous variant, accompanyingcerebral edema may be seen.

Microcystic meningiomaCharacterized by cells with thin,elongate processes encompassingmicrocysts containing pale,eosinophilic mucinous fluid.


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H istopathology

Secretory meningiomaFocal epithelial differentiationin the form of intracellular luminacontaining PAS-positive, eosinophilicsecretion.

These structures, known aspseudopsammoma bodies.

Show immunoreactivity forcarcinoembryonic antigen (CEA) and avariety of other epithelial and secretorymarkers

Secretory meningiomas may beassociated with blood levels of CEAthat drop with resection and rise withrecurrence.


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H istopathology

Lymphoplasmacyte- rich meningioma is among the rarestof variants.

Lymphoplasmacytic-richmeningiomaThis meningioma variant featuresextensive chronic inflammatoryinfiltrates often over-shadowing theinconspicuous meningothelial

component.

Systemic haematologic abnormalities, including hyperglobulinemia and iron refractoryanemia have been documented in some cases.


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H istopathology

Correlation with intra-operative findings is occasionally needed to distinguishossified meningiomas from ones exhibiting bone invasion.

Metaplastic meningioma

Mesenchymal componentsincluding osseous, cartilaginous,lipomatous, myxoid or

xanthomatous tissue,singly or in combinations.


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H istopathology

C hordoid meningioma

WHO Grade II

Consisting predominantlyof tissue histologically similar tochordoma, featuring cords ortrabeculae of eosinophilic, oftenvacuolated cells in an abundantmucoid matrix background.

Chordoid meningiomas

are typically large, supratentorialtumours that exhibit a very highrate of recurrence followingsubtotal resection

Chronic inflammatory infiltrates, often patchy, maybe prominent.

Infrequently, patients have associatedhaematological conditions, such as Castleman sdisease


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H istopathology

Composed of polygonal cells with clear, glycogen-rich cytoplasm and prominentblocky perivascular and interstitial collagen.

C lear cell meningioma

WHO Grade II A rare meningioma variant, it showsprominent PAS-positive, diastasesensitivecytoplasmic clearing due to glycogenaccumulation.

Classic features of meningioma arefew; whorl formation is vague at bestand no psammoma bodies are seen.

P roclivity for the cerebellopontine

angle and cauda equina region.

It also tends to affect youngerpatients.


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H istopathology

Increased mitotic activity is defined as 4 or more mitoses per 10 high-power(40x) fields (defined as 0.16 mm2).

Atypical meningioma

WHO Grade II Increased mitotic activity or three ormore of the following histologicfeatures:Increased cellularitySmall cells with a high nuclear:Cytoplasmic ratioP rominent nucleoliUninterrupted patternless or sheet-like growth.Foci of spontaneous or

geographic necrosis.

Simply combine hypercellularity with 5 or more mitoses per 10 high power fields.

meningiomas dr david cuenca

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