Neuropathology of CNS Tumors Flashcards Preview

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Flashcards in Neuropathology of CNS Tumors Deck (74)
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1
Q

What are the 7 major histopathological categories of CNS tumors?

A
Tumors of neuroepithelial tissue
Tumors of cranial and spinal nerves
Tumors of the meninges
Lymphomas and hematopoietic neoplasms
Germ cell tumors
Tumors of the sellar region
Metastatic tumors
2
Q

What are the 3 types of glial cells and the names of the tumors that arise from them?

A

Astrocytes -> astrocytomas
Oligodendrocytes -> oligodendrocytomas
Ependymal cells -> ependymomas

3
Q

Of the 7 main histopathological categories of CNS tumors, which is most common?

A

Tumors of neuroepithelial tissue.

4
Q

What are the two broad categories of astrocytomas?

A

Diffuse, infiltrating

Well-circumscribed

5
Q

What are the 3 grades of diffuse, infiltrating astrocytoma? What’s the WHO grade level for each?

A
Diffuse Astrocytoma (WHO Grade II)
Anaplastic Astrocytoma (WHO Grade III)
Glioblastoma (WHO Grade IV)
6
Q

What are the 3 relatively circumscribed astrocytomas?

A

Pilocytic astrocytoma
Pleomorphic xanthroastrocytoma (PXA)
Subependymal giant cells astrocytoma

7
Q

What are the pathological features that define astrocytoma (WHO Grade II)?

A

Atypia, no mitoses

8
Q

What are the pathological features that define anaplastic astrocytoma (WHO Grade III)?

A

Atypia with mitoses.

9
Q

What are the pathological features that define glioblastoma (WHO Grade IV)?

A

Atypia, mitoses, and vascular proliferation and/or necrosis

10
Q

What’s the purpose of grading CNS tumors? (2 points)

A

Predicting biological behavior (i.e. prognosis).

Guiding therapy.

11
Q

Do any tumors of the CNS have a capsule?

A

Nope. Some are “well-circumscribed,” but no capsule.

12
Q

What will you see in low power histology of white matter in diffuse fibrillary astrocytoma (WHO Grade II)? (3 things)

A

Increased cellularity
Elongated, irregular hypochromatic nuclei
Meshwork of fibrillary processes

13
Q

What will you see in high power histology of white matter diffuse fibrillary astrocytoma (WHO grade II)? What won’t you see?

A

Irregular, pleomorphic angulated nuclei. Won’t see mitoses.

contrast with the regular, round nuclei of oligodendrocytes that should usually dominate the white matter

14
Q

What are the characteristics of gemistocystic variant diffuse astrocytoma (WHO grade II)?

A

Plump cells with glassy pink cytoplasm.

15
Q

What histological feature distinguishes anaplastic astrocytoma (WHO grade III) from diffuse astrocytoma (WHO grade II)?

A

mitoses will be present in anaplastic astrocytoma

16
Q

What’s GBM?

A

glioblastoma

it’s an old abbreviation…

17
Q

What’s a serious, acute complication of a brain tumor?

A

Hemorrhage -> increased ICP -> herniation

18
Q

What will you see on histology of glioblastoma (WHO grade IV)?

A

Areas of necrosis

Neoangiogenesis (glomeruloid tufts)

19
Q

What are glomeruloid tufts?

A

Areas of neoangiogenesis. (They resemble glomeruli, histologically).

20
Q

What’s the difference between primary and secondary GBM?

A

Primary arises de novo.
Secondary has evolved from a grade II astrocytoma.
(the genetic mutations driving these cancers are different)

21
Q

What’s the major genetic change in primary glioblastoma?

A

EGFR overexpression.

22
Q

What are the 2 major genetic changes in secondary glioblastoma?

A

p53 (aka TP53) mutation

IDH1 / IDH2 mutation

23
Q

What grade are relatively circumscribed astrocytomas?

A

I or II

24
Q

If you’re going to have a brain tumor, which one would you most want?

A

Pilocytic astrocytomas - they have the best prognoses

25
Q

What’s the most common genetic mutation that drives pilocytic astrocytoma?

A

BRAF-KIAA1549 fusion oncogene

26
Q

What does a low power view of pilocytic astrocytoma histology look like?

A

Biphasic architecture: compact and cystic/spongey areas

27
Q

What’s special about the histology of the cystic/spongey areas of pilocytic astrocytoma?

A

Eosinophilic granular bodies.

28
Q

What’s special about the histology of compact areas of pilocytic astrocytoma?

A
Spindle-shaped / "hair-like" / pilloid cells, which are elongated fibrillary astrocytes.
Rosenthal fibers (eosinophilic, corkscrew shaped things)
29
Q

What does the histology of an oligodendroglioma look like?

A

Oligodendrocytes everywhere. Too many. Too closely packed.

30
Q

What grade can’t oligodendrogliomas be? Why?

A

Grade I. They’re too infiltrative.

31
Q

What’s a common presentation of oligodendroglioma in a young person?

A

Sudden onset of seizures.

32
Q

What does oligodendroglioma look like histologically? (2 things)

A

Cells with small, centrally located nucleus and scant, clear cytoplasm.
Branching capillaries.

33
Q

Why is oligodendroglioma called the “chicken” tumor?

A

The cells look like fried eggs, and the branching capillaries look like chicken wire (…sort of).

34
Q

Most common genetic changes in oligodendroglioma? Do these changes have prognostic value?

A

Loss of heterozygosity in 1p and 19q. These genetic changes seem to actually be associated with better outcomes…

35
Q

What’s an ependymal rosette? Are they typically found in ependymomas?

A

A cluster of ependymal cells surrounding a central lumen. Found in a “minority” of ependymomas.

36
Q

What are pseudorosettes?

A

Perivascular clusters of neoplastic ependymoma cells.

37
Q

Who gets embryonic CNS tumors?

A

Children. They’re rare in adults.

38
Q

What grade are all embryonic CNS tumors?

A

IV - high grade.

39
Q

What’s the most common embryonic CNS tumor?

A

Medulloblastoma.

40
Q

From what area of the CNS do medulloblastomas arise?

A

The vermis of the cerebellum.

41
Q

Why do medulloblastomas produce headache and vomiting?

A

Invasion of 4th ventricle -> obstructive hydrocephalus -> increased ICP.

42
Q

Macroscopic features of medulloblastoma? (Name 5… color, texture, etc.)

A
Well circumscribed.
Solid, but sometimes cystic or nodular.
Gray / pink.
Soft/gelatinous or firm, depending on connective tissue.
Small foci of necrosis, if present.
43
Q

From what embryological origin are medulloblastomas thought to arise?

A

Granular neuron precursor cells, which produce the external granular layer of the cerebellum, and usually disappear within the first postnatal year.

44
Q

What does medulloblastoma look like histologically?

A

Densely packed, small cells with round nuclei and high N/C ratio.
Lots of mitosis.
Sometimes Homer Wright rosettes are present.

45
Q

What are Homer Wright rosettes?

A

Clusters of tumor cells encircling neuropil. Suggestive of neuronal differentiation.

46
Q

What’s a way to detect neuronal differentiation in medulloblastoma?

A

Immunostain for neurofilament protein.

47
Q

Are medulloblastomas genetically homogenous?

A

nope.

48
Q

What are 3 main tumors of cranial and spinal nerves?

A

Schwannomas (neurilemmomas), neurofibromas, and malignant peripheral nerve sheath tumors.

49
Q

If you see a patient with bilateral acoustic / vestibular Schwannoma, what should be at the top of your DDx?

A

NF2 - neurofibromatosis type II (a hereditary condition)

50
Q

What are neurofibromas? What are the 2 variants?

A

Tumors of the nerve sheath (really, non-myelinating Schwann cells, says Wikipedia)

  • Dermal (nodular skin lesion)
  • Intraneural / solitary / plexiform
51
Q

If you see multiple neurofibromas, what should be at the top of your DDx?

A

NF1 - neurofibromatosis type I

52
Q

Would a meningioma arise from the dura or arachnoid mater?

A

Arachnoid. Meningiomas are from the leptomeninges.

53
Q

What are 3 risk factors for meningioma?

A

Increased age, being female, having NF2

54
Q

What’s the typical histological pattern of transitional meningioma?

A

“Whirls and cords” (see slide 56)

55
Q

What immunostain can be used to identify meningioma?

A

EMA

56
Q

3 histological variants of meningioma? Histological buzzwords?

A

Transitional - whirls and cords
Psammomatous - compact cords with psammoma bodies…
Fibrous - …fibrous…

57
Q

Do adults or kids have more metastatic cancers in the CNS? Why?

A

Adults, as these come from tumors that affect adults more, such as carcinomas.

58
Q

How common is it to get a solitary metastasis in the CNS?

A

Only happens 50% of the time. Often there are multiple mets.

59
Q

In the general population, what percentage of cancers are primary CNS neoplasms?

A

2%

60
Q

In children, what percentage of cancers are primary CNS neoplasms?

A

20% (2nd most common, after leukemias)

61
Q

When you include secondary (metastatic) CNS neoplasms, what does the age distribution look like?

A

Bimodal. Peak in childen < 5 years. Peak at 45-70 years.

62
Q

What are the 2 most common CNS tumors of childhood?

A
Embryonal/medulloblastoma (predominates in 0-4 yrs).
Pilocytic astrocytoma (predominates in 5-19 yrs old)
63
Q

Which primary CNS tumors have sex-based differences in frequency?

A

Gliomas and embryonic tumors - more in males.

Meningiomas - more in females

64
Q

What types of CNS neoplasm does Neufibromatosis type 1 (NF1) predispose people to? (name 4)

A

Neurofibroma.
Malignant nerve sheath tumor.
Optic nerve astrocytoma.
Meningioma.

65
Q

What types of CNS neoplasm does Neufibromatosis type 2 (NF2) predispose people to? (name 2)

A

Schwannoma
Meningioma
Ependymoma

66
Q

What types of CNS neoplasm does tuberous sclerosis predispose people to? What else does it cause?

A

Subependymal giant cell astrocytomas (which often causes hydrocephalus).
Mental retardation and seizures.

67
Q

What’s the one really well-proven environmental risk factor for brain tumors? Which brain tumors does it predispose to?

A

X-irradiation (i.e. for cancer treatment, not diagnostic X rays).
Predisposes to a) meningiomas and b) astrocytomas/neuroepithelial tumors in children treated for ALL.

68
Q

What are some risk factors for primary CNS lymphoma?

A

Acquired or congenital immunodeficiency.

69
Q

4 signs/symptoms that can help you localize a tumor?

A

Epilepsy (focal or generalized), focal neuro deficits, mental changes, obstructive hydrocephalus (headache)

70
Q

Review: Signs/symptoms of raised ICP? (name 4)

A

Headache (postural / morning headache)
Vomiting (esp. children)
Papilledema
Clouding of consciousness and coma

71
Q

What are Duret hemorrhages?

A

Pons hemorrhages secondary to transtentorial herniation causing stretching/tearing of brainstem vasculature.

72
Q

3 nerves/tracts that can be compressed in herniation? Associated sign?

A

Abducens -> lateral gaze palsy
Occulomotor -> blow pupil / “down and out” eye
Cerebral peduncle -> hemiparesis ipsilateral to lesion (at first, then may become bilateral).

73
Q

Bilateral acoustic-vestibular Schwannoma is characteristic of which familial syndrome?

A

NF2

74
Q
Oligodendroglioma in left frontal lobe with cortex infiltration. Most likely symptom is... 
A. Ataxia &amp; dysmetria
B. Mental status changes + shizophrenia
C. Epileptiform fits
D. Loss of vision
A

C. Epileptiform fits - due to cortical involvement.