CNS Tumors: Bemis

Question 1

Describe primary CNS tumors.

Answer 1

Poorly circumscribed, usually single, location varies by type.

Question 2

Describe metastatic tumors to the CNS.

Answer 2

Well circumscribed, multiple, junction between gray and white matter, often pleomorphic (variable shaped nuclei), infiltrate via pathways of least resistance.

Question 3

What does the WHO Grading intended to do?

Answer 3

Predict the biological behavior of a tumor and to influence your choice of therapy

Question 4

What is adjuvant treatment?

Answer 4

Follows primary treatment. The goal is to remove any residual cancer cells.

Question 5

Where are 70 % of tumors in children?

Answer 5

Posterior Fossa

Question 6

Where are 70 % of tumors in adults?

Answer 6

Supratentorial

Question 7

What is a WHO Grade 1 tumor like?

Answer 7

Low proliferative potential, possible to cure following resection alone!

Question 8

What is a WHO Grade 2 tumor like?

Answer 8

Infiltrative but low proliferative activity, if removed will often recur (>5 year survival)

Question 9

What is a WHO Grade 3 tumor like?

Answer 9

Histological evidence of malignancy: nuclear atypic and much mitotic activity (2-3 year survival).

Question 10

What is a WHO Grade 4 tumor like?

Answer 10

Cytologically malignant, mitotically active, necrosis prone, usually fatal.

Question 11

How does radiation work?

Answer 11

Breaks DNA to induce death.

Question 12

What type of cells are often resistant to radiation?

Answer 12

Brain tumor stem cells.

Question 13

What types of cells to Gliomas (Astrocytomas) usually arise from?

Answer 13

Astrocytes, Oligodendrocytes, Ependymal cells

Question 14

What often prevents complete excision of Gliomas?

Answer 14

Infiltrative borders

Question 15

What is the highest grade, most malignant Astrocytoma?

Answer 15

Glioblastoma

Question 16

Describe the Astrocytoma grading scale.

Answer 16

I. Pilocytic Astrocytoma (benign: low proliferative potential)
II. Diffuse Astrocytoma (Low proliferative potential but infiltrative)
III. Anaplastic Astrocytoma (shows more cellular regions, more pleomorphism, more mitosis)
IV. Glioblastoma (necrosis, microvascular proliferation)

Question 17

Describe Pilocytic Astrocytomas. Who usually gets them?

Answer 17

Often cystic, bipolar cells with long hair-like processes. Contain Rosenthal Fibers (Corkscrew morphology, very pink, composed of GFAP (Glial Fibrillary Acidic Protein)), Biphasic (lose and dense areas).

Children
Excellent prognosis
If you have a mutated BRAF (detected using FISH), the outcome is generally worse.

Question 18

Describe Diffuse Astrocytomas. Who usually gets them?

Answer 18

Slowly progress into Anaplastic Astrocytomas. Surgical removal then radiation.

Histology: Gemistocytic astrocytoma
The presence of fibrils is not good.
Genetics: Oligodendrocytomas do better.

Age: 20’s-40’s

Question 19

Why isn’t chemo good for a diffuse astrocytoma?

Answer 19

Because the cells are growing slowly.

Question 20

Describe Anaplastic Astrocytoma.

Answer 20

GFAP positive. Mitotic figures.

Question 21

Why do we see GFAP?

Answer 21

It is a principle intermediate filament in mature astrocytes. It modulates astrocyte motility and shape. Following an injury, astrocytes are activated –> Astrogliosis –> Rapid synthesis of GFAP.

Question 22

Describe a Glioblastoma.

Answer 22

MOST COMMON PRIMARY BRAIN TUMOR IN ADULTS AGE 45-75. Mean survival: 10 months.
Pseudopalisading necrosis.
Butterfly glioma: crosses midline via corpus callosum.
Sx: progressive motor weakness, headaches, Increased ICP, Seizures.

Question 23

Why do we need to know if we are working with a primary or secondary Glioblastoma?

Answer 23

For treatment purposes.

Primary are a Glioblastoma from the first symptom (EGFR, p53 mutations).

Secondary are formed from a common precursor mutation in IDH 1/2 (Can differentiate into Diffuse astrocytoma or Oligodendroglioma which can both become secondary Glioblastomas).

Question 24

Describe an oligodendroglioma.

Answer 24

Less common (10 % of gliomas in adults).
Sx. Seizures.
Mean survival: 10 years.

Deletion of 1p and 19q improves survival.

Morphology: sharply circumscribed round nuclei with cytoplasmic halos. Most are calcified. Delicate capillary network.

Question 25

Describe an ependymoma.

Answer 25

Usually in kids, near the 4th ventricle.
Slow growing but have a 4 year prognosis.

Morphology: Rosettes and pseudorosettes.

Question 26

What is the adult version of a ependymoma called and where is it located?

Answer 26

Myxopapillary variant. It is in the spinal cord.

Question 27

Describe a medulloblastoma.

Answer 27

WHO Grade IV. 
Children.
Very radiosensitive
Cerebellum.
Males>females

i(17q) = poor prognosis (it is an isochrome: puts p and p or q and q of chromosome arms together).

Histology: Homer-Wright Rosettes (proteins in the center).

Question 28

Describe a meningioma.

Answer 28

2nd most common primary brain tumor.
Benign.
Tumor of arachnoid cells.
Slow growing.
Attached to dura and compresses brain.

Histology: Synctial (swirling pattern)
                 Psammoma bodies (calcium deposits).

Question 29

Describe a schwannoma.

Answer 29

3rd most common brain tumor.
Commonly located at CN VII at the cerebellopontine angle.
Hearing loss, tinnitus.
Good prognosis after surgery.