Topic 120: brain tumors

Question 1

CNS tumors: what % is a primary tumor? how common are they? Where do they tend to arise?

Answer 1

50-70% are primary, the rest are metastases
-20% of childhood tumors are CNS tumors

• In children they appear in the posterior fossa
• in adults they are frequently in the supratentorial area

Question 2

CNS tumors are characterized by?

Answer 2

• histology - the difference between benign and malignant are more subtle here
• growth pattern
• site of tumor
• metastatic properties

Question 3

What are the 5 types of CNS tumors?

Answer 3

• gliomas
• neuronal tumors
• poorly differentiated
• meningiomas
• metastases

Question 4

gliomas can be (three types)

Answer 4

Astrocytoma (fibrillary and pilocytic)
oligodendrogliomas
ependymomas

Question 5

fribrillary astrocytoma are how common? what kind of differentiation can you see? what is the survival rate?

Answer 5

• 80% of adult primary brain tumors
• there is a wide spectrum of differentiation: type 1-4, 4 being least differentiated
• very poor prognosis, mean survival is 8-10 months

Question 6

pilocytic astrocytoma has what prognosis? what is the morphology and who gets it the most?

Answer 6

• typically benign
• cystic
• common in children and young adults

Question 7

oligodendrogliomas are how common? what are the usual symptoms? what is the prognosis?

Answer 7

• 10% of gliomas
• often appears with seizures, commonly in white matter
• better prognosis

Question 8

ependymoma appear where? what commonly occurs with them?

Answer 8

• arise in ependyma lined ventricles, especially in the spinal cord
• CSF dissemination is common

Question 9

neuronal tumors include which three types?

Answer 9

• Central neurocytoma: low grade tumor found in ventricular system
• gangliomas - mix of glial elements, typically slow growing but can sometimes progress rapidly and cause seizures
• dysembryoplastic neuroepithelial tumors - low grade tumors, good prognosis. occur on temporal lobe

Question 10

poorly differentiated neoplasms: what is the most common? what is the prognosis? who gets it the most?

Answer 10

Medulloblastoma - 20% pediatric tumors, always in the cerebellum.

• it is highly malignant but very radiosensitive.
• if totally excised, there is a 75% survival rate

Question 11

what is the tumor of the meninges? what do they arise from?

Answer 11

meningioma. almost always benign, arise from meningothelial cells of the arachnoid

Question 12

what cancer typically metastasizes to the brain? how common is it?

Answer 12

25-50% of intracranial tumors are metastases

80% come from–

• lung
• breast
• skin
• kidney
• GI

Question 13

Because lung cancer frequently metastasizes to the brain, what syndrome is common? what type of tumor produces this and what are the neurological symptoms?

Answer 13

Small cell lung cancer frequently metastasizes to cause paraneoplastic syndrome

• cerebellar degeneration
• limbic encephalitis
• sensory neuropathy (dec pain sensation)

Question 14

what are the PNS tumors?

Answer 14

• schwannoma
• neurofibroma (cutaneous and plexiform)
• malignant peripheral nerve sheath tumor

Question 15

What is a schwannoma? what symptoms do they causes? what is the prognosis

Answer 15

a benign tumor arising from schwann cells that cause symptoms due to the compression of the nerve.
-vestibulocochlear nerve – tinnitus and hearing loss

they are easily surgically removed because they do not infiltrate the nerve

Question 16

neurofibroma are two categories:

Answer 16

dermal neurofibromas - most common, occurs in the skin as a nodule and is not very dangerous

plexiform neurofibroma - difficult to remove as it grows from a group of nerves. they cause disfigurement and can metastasize

Question 17

malignant peripheral nerve sheath tumors come from what?

Answer 17

these locally invasive tumors either come from plexiform neurofibromas or arise de novo. They do not originate from schwannomas!

they can also occur after radiation