Week 4: Path-Neoplasms of central nervous system

Question 1

Indicate the relative incidence of brain tumors in adults and children

Answer 1

• 1.4% of all cancers
• 20-25% of pediatric cancers
• much more common in children, 2nd most common type of neoplasm
• 6th most common type in adults

Question 2

Indicate the different in localization of brain tumors with respect to the tentorium in children and adults

Answer 2

Children: 70% below tentorium
adults: 70% above tentorium

Question 3

Define Malignancy for brain tumors

Answer 3

• histologically: anaplasia, mitotic activity, necrosis
• clinically: depends on site, where excision may not be possible
• infiltration (but circumscribed expansile can still have a negative effect)

Question 4

List three ways that brain tumors spread within and outside the nervous system

Answer 4

1. via meninges
2. via CSF
3. Into subcortical matter

Question 5

Describe the 4 main growth patterns of brain tumors with three examples of each

Answer 5

1. Mass with local expansion: meningioma, schwannoma, ependymoma
2. mass with local infiltration: malignant meningioma, astrocytoma, metastatic carcinoma
3. diffuse infiltration: pontine glioma, astrocytoma, glioblastoma multiforme
4. multifocal: primary lymphoma, glioblastoma multiforme, metastases

Question 6

Define the 4 tiered WHO grading system for gliomas

Answer 6

• Grade I: discrete, exemplified by juvenile pilocytic astrocytoma. Well circumscribed with good prognosis. Typical biphasic appearance with Rosenthal Fibers
• Grade IV: glioblastoma multiforme-mitotically active, atypia. Necrosis, endothelial proliferation. 9-18 mo prognosis.

Question 7

Describe the characteristics of meningiomas. Histologically.

Answer 7

• from arachnoid granulations
• look epithelial
• whorly pattern
• may see psammoma bodies (Ca2+)

Question 8

Describe the characteristics of glioblastoma multiform

Answer 8

• necrosis with palisading tumor cells

- malignant high grade tumor

Question 9

Describe the characteristics of ependymoma.

Answer 9

• intraventricular tumor
• with rosettes
• small round sheets of cells

Question 10

Describe the characteristics of medullablastoma.

Answer 10

• in the cerebellum
• histology: small round sheets of cells (mostly nucleus, little cytoplasm)
• children

Question 11

Describe the characteristics of swanomma. Compare it with neurofibroma.

Answer 11

• benign tumor of Schwann cells- compresses adjacent nerve
• can be surgically excised from nerve of origin
• occurs in NF2 (especially vestibular nerve)
  Neurofibroma:
  - benign tumor of Schwann cells and fibroblasts
  - expands nerve of origin- can not be surgically excised from nerve of origin
  without sacrificing the nerve
  - occurs in NF1- rarely becomes malignant

Question 12

juvenile pilocytic astrocytoma

Answer 12

• well circumscribed, cystic
• Rosenthal fibers: bright red
• biphasic
• hairlike processes
• like cerebellum but can occur elsewhere
• most common glioma in children
• more common in patients with neurofibromatosis type 1-often involves optic nerve