Neoplasms of the CNS Flashcards
1
Q
Incidence of brain tumors
A
- 1.4% of primary neoplasms in adults, 20-25% in children
- 6th most common group of tumors in adults, 2nd most common in children
- Increasing incidence of malignant gliomas and lymphoma
2
Q
Difference in localization of brain tumors
A
- Supratentorial compartments vs infratentorial compartments
- Most in adults are supratentorial (above cerebellum)
- Most in children are infratentorial (in cerebellum)
3
Q
Classification of brain tumors
A
- Very rare are they benign (except in pituitary), since they cause mass effect and blocks flow of CSF (hydrocephalus)
- Metastatic in 20% of cases
- Brain tumors are not derived from neurons but rather from other intracranial cells such as meninges or glial cells
- Primary tumors can be intracerebral (60%) or extracerebral (20%)
- Intracerebral: glioma (astrocytoma), PNET: peripheral neuroectoderm tumor (medulloblastoma, most common in children), primary CNS lymphoma
- Extracerebral: meningioma and schwannoma
- Last 20% of brain tumors are metastatic
4
Q
Benign vs malignant
A
- While many of the brain tumors rarely spread to other locations, they are still invasive and thus are malignant
- Can tell by histology, anapestic cells much more likely to be malignant
- All intracranial tumors are going to produce a mass effect and thus increase intracranial pressure
- The mass can also block flow of CSF, resulting in hydrocephaly and further increasing pressure
- Thus, even benign neoplasms harmless, and invasive (malignant) neoplasms that do not metastasize will produce many problems
5
Q
Brain metastases
A
- Follow a pattern: tend to occur as multiple focal lesions (not primary brain tumor), entered the brain through the CSF
- Many tend to be adenocarcinoma
- Can seed into the meninges, ventricles, cortex, subcortical white matter, anywhere in CNS
- Metastatic tumors often superficial and cystic
- Most primary lesions are single focal lesions
6
Q
Intracranial, extracerebral tumors: meningioma and schwannoma
A
- Schwannoma is only PNS
- Tumors usually derived from arachnoid layer (granulations), some will be malignant
- Are always a separate mass from the brain tissue (circumscribed and attached to dura, b/c the arachnoid layer attaches to dura)
- Can occur anywhere there is meninges (brain or SC)
7
Q
Meningiomas
A
- Arise from arachnoid granulations
- Multiple histologic patterns: often are whirls of sqamous/epithelial-looking cells, can be sheets of cells, or spindle-like
- See psammoma bodies: dark round spherical structures (not strictly indicative of meningiomas since other diseases cause them)
8
Q
Schwannoma
A
- PNS tumors derived from schwann cells
- Can be in cranial nerves, nerve roots, or in periphery
- Usually benign but can be malignant
- Type of tumor composed of neurons: ganglioma
9
Q
Intracranial, intracerebral tumors: glioma
A
- Classification of gliomas: astrocytoma (15%), glioblastoma (30%), oligodendroglioma (5%), ependymoma (5%)
- GBM is most common intracerebral tumor
- Astrocytoma and GBM tend to be anywhere
- ODG tend to be in white matter
- Ependymoma tend to be in ventricles
10
Q
Grading of astrocytic neoplasms
A
- Grade I: juvenile pilocytic astrocytoma, benign type behavior (well circumscribed, good prognosis)
- Gade II: astrocytoma
- Grade III: anaplastic astrocytoma
- Grade IV: GBM, invasive and destructive w/ rapid growth (poor prognosis)
- Can get a transition from a low grade to a higher grade
11
Q
Pilocytic astrocytoma
A
- Tends to be in cerebellum, often in children
- Produces a discrete, cystic mass
- Can also be in optic nerve
- Histologically, there is a biphasic appearance (solid and open/mixoid)
- Cells look like astrocytes (stellate cells)
- Can see rosenthal fibers which are highly eosinophilic fibers that are astrocyte cytoplasm
- Fewer mitotic figures (more mitotic figures the more rapidly growing and thus higher grade)
12
Q
Glioblastoma multiforme
A
- Very rapidly growing, more often in adults
- Is often necrotic due to rapid growth, necrotic areas can be cystic
- Grows often in path of least resistance, which often is through the corpus collosum
- HIstologically they are definitively diagnosed by necrosis surrounded by pallisading tumor cells
- The necrosis looks like empty eosinophilic space, and is surrounded by a “wall” of aligned cell nuclei (pallisading tumor cells w/ lined up nuclei)
- Associated w/ p53 mutations and EGF-R amplification
13
Q
Oligodendroglioma
A
- ODG are not very common, usually benign, discrete, gelatinous mass
- Masses are full of oligodendrocytes w/ fried egg shape
- Usually have very rich vascularity, this prevents necrosis
14
Q
Ependymoma
A
- Usually circumscribed mass that extends into ventricle, often benign
- Histologically can look like adenomas since they form ependymoma rosettes (looks glandular)
- Difference btwn this and choroid plexus papilloma is the papilloma usually over-produces CSF (doesn’t produce rosettes)
15
Q
Intracranial, intracerebral tumors: medulloblastoma
A
- Most common in children, can occur in adults
- All occur in cerebellum (by definition), are small round blastoma tumors in cerebellum
- Are usually discrete, but not completely circumscribed (often irregular)
- Histologically there are sheets of cells that are mostly dark nuclei (little cytoplasm)
