Meningioma

Question 1

What % of all primary CNS tumors do meningiomas account for in adults?

Answer 1

36%. Meningioma is the most common benign 1st-degree CNS tumor. (Central Brain Tumor Registry of the United States, 2016 update) Autopsy studies suggest prevalence of subclinical meningiomas in up to 3% of the general population

Question 2

What are the age and sex predilection for meningiomas?

Answer 2

The incidence of meningiomas increases with age (mean age at Dx 62, incidence peaks in the 8th decade). Females are more commonly affected than males (2:1).

Question 3

What are some risk factors for meningiomas?

Answer 3

Prior RT (RR 10, median interval to development 20 yrs), NF-2 (5%–15% risk of multiple meningiomas), and HRT in women (RR 2).

Question 4

Which protein is defective in NF-2, and to what else does NF-2 predispose?

Answer 4

Merlin; bilat acoustic neuromas/ependymomas and juvenile subcapsular cataracts

Question 5

What histologic features can be seen in meningiomas?

Answer 5

Psammoma bodies and calcifications

Question 6

List 5 negative prognostic factors for meningiomas.

Answer 6

Negative prognostic factors for meningiomas:

1. High grade
2. Young age
3. Chromosome alterations
4. Poor PS
5. STR

Question 7

What is the grade classification of meningiomas?

Answer 7

WHO grade I (benign), grade II (atypical), and grade III

anaplastic/malignant

Question 8

According to the 2007 WHO classification, what criterion upgrades an otherwise grade I meningioma to grade II?

Answer 8

Brain invasion

Question 9

What is the prevalence of grades II–III meningiomas?

Answer 9

6% and 4%, respectively. 90% are grade I.

Question 10

Name the histologies associated with WHO grades II–III meningiomas.

Answer 10

Grade II: atypical, clear cell, chordoid

Grade III: anaplastic, rhabdoid, papillary

Question 11

Of grade I meningiomas, which histologic subtype is most aggressive?

Answer 11

The angioblastic subtype is the most aggressive grade I meningioma.

Question 12

What is the OS difference b/t atypical and anaplastic meningiomas?

Answer 12

Atypical 12 yrs vs. anaplastic 3.3 yrs (Yang SY et al., J Neurol Neurosurg Psychiatry 2008)

Question 13

What are some prognostic factors identified for anaplastic meningiomas?

Answer 13

Brain invasion, adj RT, extent of resection, and p53 overexpression (Yang SY et al., J Neurol Neurosurg Psychiatry 2008)

Question 14

What is the most common Sx at presentation for meningiomas?

Answer 14

HA is the most common presenting Sx.

Question 15

What is the appearance of meningiomas on CT/MRI?

Answer 15

Homogeneously and intensely enhancing mass, +/– dural tail

Question 16

What % of meningiomas exhibit a dural tail? In what other tumors/lesions can dural tails be seen?

Answer 16

60%. Dural tails can also be seen in chloroma, lymphoma, and sarcoidosis.

Question 17

What proportion of incidentally found meningiomas remain stable on imaging?

Answer 17

Two-thirds. The majority remain stable on imaging.

Question 18

For meningiomas, with what are slower growth rates associated?

Answer 18

Slower growth rates are associated with older pts and calcifications.

Question 19

What surgical grading system is used in meningiomas? For what does it predict?

Answer 19

Simpson grade (I/GTR–V/decompression) predicts the likelihood of LR.

Question 20

In what anatomic regions is GTR more difficult to achieve for meningioma resection?

Answer 20

Cavernous sinus, petroclival region, postsagittal sinus, and optic nerve

Question 21

How is optic sheath meningioma diagnosed?

Answer 21

Optic sheath meningioma is diagnosed clinically/radiographically by a neuroophthalmologist/
MRI (no Bx).

Question 22

What are the Tx paradigms for meningiomas?

Answer 22

Meningioma Tx paradigms:
If incidental/asymptomatic: observation
If grade I and symptomatic/progressive: Sg + RT (if STR)
If grade II (high risk) or III: Sg + RT

Question 23

For which types of meningioma is RT the primary Tx modality?

Answer 23

Optic nerve sheath and cavernous sinus (inaccessible regions)

Question 24

When should observation be considered?

Answer 24

Observation should be considered with incidental/asymptomatic and stable lesions. Consider Sg for large (≥30 mm) lesions, if accessible.

Question 25

When is RT utilized after Sg for meningiomas?

Answer 25

RT should be utilized after Sg if there is recurrent Dz or STR or if there is anaplastic histology or brain invasion.

Question 26

What is the avg time to recurrence after Sg for meningiomas?

Answer 26

4 yrs is the avg time to recurrence after Sg.

Question 27

What are the 10-yr recurrence rates with Sg alone after either GTR or STR of meningioma?

Answer 27

10-yr recurrence rates with Sg alone are ∼10% after GTR and 60% after STR.

Question 28

Is there a benefit to upfront RT after STR for grade I meningioma?

Answer 28

This is controversial (upfront control rates are considered equivalent to salvage rates). RTOG 0539 showed RT benefit for WHO II (post-STR) and all WHO III tumors (Rogers L et al., NeuroOncol 2017) and may address this question in its low-risk cohort.

Question 29

What are the RT doses employed for meningiomas?

Answer 29

RT doses are 45–54 Gy for benign and 60 Gy for malignant tumors (CTV = GTV + 1–2 cm).

Question 30

Is there any RT dose–response data for meningiomas?

Answer 30

Yes. Goldsmith BJ et al. showed improved PFS with doses >52 Gy. (J Neurosurg 1994)

Question 31

What are typical SRS doses used for meningiomas?

Answer 31

Typical SRS doses range from 12–16 Gy to 50% IDL at the tumor margin (depending on location/size).

Question 32

What is the 5-yr LC rate for meningiomas after SRS?

Answer 32

The 5-yr LC rate is ∼95% for grade I tumors. For grades II–III, it is 68% and 0%, respectively. (Stafford SL et al., Neurosurgery 2001)

Question 33

What poor prognostic factors have been identified in pts receiving SRS for meningiomas?

Answer 33

Male sex, previous Sg, tumors located in parasagittal/falx/convexity regions (Pollock BE et al., Neurosurgery 2012)

Question 34

Should the dural tail be covered in the RT field?

Answer 34

In general, no; however this is controversial. Some studies have shown improved 5-yr DFS when the dural tail was included in SRS Rx isodose. (DiBiase SJ et al., IJROBP 2004)

Question 35

What is the surgical complication rate after resection for meningiomas?

Answer 35

After resection, the surgical complication rate is 2%–30% depending on the location/type; 1%–14% mortality (worse in the elderly).

Question 36

If observed, pts with meningiomas should get MRIs at what intervals?

Answer 36

At 3 mos, 6 mos, and 12 mos, then every 6–12 mos for 5 yrs, then every 1–3 yrs if stable (NCCN 2018)

Question 37

What is the toxicity rate for SRS if doses >16 Gy are used?

Answer 37

There is temporary toxicity in 10% of pts and permanent toxicity in 6% of pts. Perilesional edema is observed in 15%. (Kullova A et al., J Neurosurg 2007)

Question 38

How are optic nerve sheath/cavernous sinus meningioma pts followed?

Answer 38

These pts should be followed with serial MRIs, neuro-ophthalmology exams, and regular endocrinology exams.