Work-up & Staging

Question 1

What are some common presenting Sx for MB?

Answer 1

HA (nocturnal or morning), n/v, altered mentation d/t hydrocephalus, truncal ataxia, head bob, and diplopia (CN VI)

Question 2

What causes the common presenting Sx in MB?

Answer 2

Obstructive hydrocephalus/↑ ICP (HA and vomiting) and cerebellar dysfunction

Question 3

What Sx would be expected with midline vs. lat cerebellar tumors?

Answer 3

Midline tumors may cause gait ataxia or truncal instability (i.e., broad-based gate, difficulty with heel-to-toe), whereas tumors in the lat hemispheres (more common in adults) may cause limb ataxia (i.e., dysmetria, intention tremor, difficulty with heel-to-shin). ATRT more likely to involve lat hemispheres.

Question 4

What is the “setting-sun” sign?

Answer 4

Downward deviation of gaze from ↑ ICP (CNs III, IV, and VI)

Question 5

List the general workup for a PF mass at presentation.

Answer 5

PF mass workup: H&P (funduscopic exam, CN exam), CBC/CMP, MRI brain/spine, CSF cytology (may not be possible d/t herniation risk), and baseline ancillary tests. Consider bone scan and CXR depending on presentation and risk factors.

Question 6

What are some important ancillary tests to obtain prior to starting Tx?

Answer 6

Baseline audiometry, IQ testing, TSH, and growth measures

Question 7

Is a tumor Bx necessary for Dx? Is a BM Bx necessary?

Answer 7

Per current COG MB protocol ACNS0331, a tumor Bx is unnecessary; pts often go straight to Sg. BM Bx is not part of the standard workup.

Question 8

Is there any risk of CSF dissemination with shunt placement for MB?

Answer 8

No. There is no risk of CSF dissemination.

Question 9

What tests should be obtained on days 10–14 postop?

Answer 9

MRI spine, CSF cytology. (Delay until day 10 to avoid a false+ result from surgical debris.)

Question 10

When is MRI of the brain done? Of the spine?

Answer 10

MRI brain: preop and 24–48 hrs postop

MRI spine: preop or 10–14 days postop

Question 11

What can be done before Tx to reduce ICP?

Answer 11

Ventricular drain or shunt, steroids, acetazolamide (Diamox)

Question 12

List the T staging according to the modified Chang staging system for MB.

Answer 12

T1: <3 cm

T2: ≥3 cm

T3a: >3 cm, with extension into aqueduct of Sylvius or foramen of Luschka

T3b: >3 cm, with unequivocal extension into brainstem

T4: >3 cm, extends beyond aqueduct of Sylvius and/or foramen magnum

Question 13

List the M staging according to the modified Chang staging system for MB.

Answer 13

M0: no subarachnoid or hematogenous mets

M1: +CSF

M2: nodular intracranial seeding

M3: nodular seeding in spinal subarachnoid space

M4: extraneural spread (bone, BM most common in MB)

Question 14

Define standard-risk and high-risk MB.

Answer 14

Standard risk (two-thirds): >3 yo, GTR/NTR <1.5 cm2 residual, and M0

High risk (one-third): <3 yo, or STR ≥1.5 cm2 residual, or M+

Question 15

What may contribute to the poor prognosis of <3 yo?

Answer 15

Reduction in volume and/or dose or elimination of RT in very young children d/t concerns of toxicity may contribute to the poor prognosis in this age group.

Question 16

What is the most important prognostic factor at Dx for MB? What are other poor prognostic factors for MB?

Answer 16

M stage is the most important prognostic factor. Other poor prognostic factors include male sex, age <3 yrs, and unresectable Dz/STR.

Question 17

What are the T and M stages in the modified Chang staging system for medulloblastoma?

Answer 17

Question 18

Which patients are considered standard risk medulloblastoma and how should they be treated?

Answer 18

Standard risk is defined as age ≥3 years, GTR/STR (with <1.5 cm2 of residual disease) and M0.

Treatment: Surgical resection → CSI 23.4 Gy (1.8 Gy/fx) with a boost to the resection cavity to 54Gy with concurrent weekly vincristine → PCV (procarbazine, CCNU, vincristine). Of note, boost to the resection cavity plus 1.5 cm margin was compared with a boost to the entire posterior fossa in ACNS0331, which demonstrated no differences in EFS or OS.