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Book - Molavi > Chapter 26 - Brain > Flashcards

Chapter 26 - Brain Flashcards

1
Q

What are the three most useful pieces of information in diagnosing brain lesions?

A

The patient’s age

The location of the lesion

The radiographic appearance of the lesion

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2
Q

How does a demyelinating lesion appear on histology?

A

Abundant foamy macrophages and an abscence of obvious tumor cells

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3
Q

What lesions can arise from the following normal brain cells?

  1. Astrocytes
  2. Oligodendroglia
  3. Ependyma
  4. Neurons
  5. Meninges
A
  1. Astrocytoma
  2. Oligodendroglioma
  3. Ependymoma
  4. Neurocytoma, gangliocytoma
  5. Meningioma, hemangiopericytoma
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4
Q

What lesions can arise from the following brain cells?

  1. Choroid plexus
  2. Pituitary
  3. Schwann cells
  4. Stromal/vascular cells
A
  1. Choroid plexus papilloma / carcinoma
  2. Pituitary adenoma
  3. Schwannoma
  4. Hemangioblastoma
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5
Q

What lesions can arise from the following brain cells?

  1. Embryonal (immature) cells
  2. Pharynx remnants
  3. Germ cell remnants
  4. Notochord remnants
A
  1. Medulloblastoma, PNET, neuroblastoma
  2. Craniopharyngioma, Rathke cleft cyst
  3. Germinoma, teratoma
  4. Chordoma
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6
Q

How are CNS tumors graded and staged?

A

There is no “benign” & “malignant”, and there is no TNM staging.

WHO grades I-IV; I-II is “low grade”, while III-IV is “high-grade”.

Grading features are the usual.

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7
Q

How should intraoperative specimens be evaluated? Why?

A

In addition to freezing, should also be smeared and/or touch-prepped.

Highlights fibrillary processes and preserves nuclear detail. Also indicates cohesiveness of the tumor.

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8
Q

What CNS tumors are noncohesive?

A

Lymphoma, pituitary adenoma, oligodendroglioma

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9
Q

How are astrocytes divided?

A

Into diffuse (infiltrating) and circumscribed variants (basically just pilocytic astrocytoma).

Diffuse: Well-differentiated (II), anaplastic (III), and glioblastoma (IV).

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10
Q

What features define grades III and IV astrocytomas?

A

III: Hypercellularity & mitoses

IV: Microvascular proliferation or necrosis (especially pseudopalisading)

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11
Q

Describe the general morphology of an astrocytoma.

A

The tumor cells generally resemble normal cells with no visible architecture or cell borders. Recognize the presence of too many nuclei that are hyperchromatic, large, & irregularly shaped.

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12
Q

Describe the clinical significance of pilocytic astrocytoma.

A

A circumscribed and indolent form of astrocytoma occuring in young patients, usually in association with the cerebellum, optic nerve, hypothalamus, or ventricles.

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13
Q

Describe the morphology of pilocytic astrocytoma.

A

Matted hair-like background. Rosenthal fibers and eosinophilic granular bodies.

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14
Q

Name and describe two well-circumscribed astrocytomas besides pilocytic.

A

Pleomorphic xanthoastrocytoma: Seizure-causing tumor of young adults found in the cerebral cortex

Subependymal giant cell astrocytoma: Seen in tuberous sclerosis

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15
Q

What is gliosis and how does it appear?

How can it be distinguished from gliomas?

A

A reactive process with shortening of astrocytes and taking on a stellate shape.

Gliomas are more likely to be microcystic, calcified, and show mitoses & satellitosis (clustering around neurons/vessels).

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16
Q

Where are oligodendrogliomas usually located?

What grade are they?

A

Usually in the frontal / temporal lobes of adults

Usually grade II, but vascularity & necrosis will push it to grade III.

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17
Q

Describe the morphology of oligodendroglioma.

A

Small round nuclei surrounded by clear halos. Chromatin is like a plasma cell. Exhibits satellitosis. Can be net-like or microcystic & calcifying.

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18
Q

What feature is most important to identifying oligodendroglioma?

A

Deletion of 1p and/or 19q.

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19
Q

Where are meningiomas located?

How are they graded?

A

Always dural-based.

Usually grade I, but can be II (atypical) or III (malignant) with signature histologic patterns.

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20
Q

Describe the morphology of meningioma.

A

Extremely unpredictable, with 16+ subtypes. Distinguished by meningothelial cells. Look for whorls and psammoma bodies.

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21
Q

Describe the appearance of meningothelial cells.

A

Invisible cell borders, syncytial. Regular small and streaming nuclei.

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22
Q

Describe the following subtypes of meningioma:

Clear cell

Chordoid

A

Clear cell: Grade II. Glycogen-filled, so clear in appearance.

Chordoid: Grade II. Resembles chordoma, with myxoid background and cords of cells.

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23
Q

Describe the following subtypes of meningiomas:

Rhabdoid

Papillary

A

Rhabdoid: Grade III. Plump pink cells with discrete cell borders, similar to rhabdomyosarcoma

Papillary: Grade III. Syncytial meningothelial cells on fibrovascular cores.

24
Q

How can a given histologic type of meningioma be “up-graded”?

A

Cytologic criteria (cellularity, pleomorphism, >4/10hpf mitoses, necrosis)

Brain invasion

25
Q

What are hemangiopericytoma and solitary fibrous tumor?

A

Tumors that probably arise from hemangiopericytes that are dural-based and well-circumscribed.

Hemangiopericytoma is more aggressive: Blue & cellular with staghorn vessels. More nuclear than meningiomas…

26
Q

What tumors are usually seen infratentorially?

What are some considerations for frozen here?

A

Usually tumors of children: Medulloblastoma, pilocytic astrocytoma, ependymoma. Also acoustic neuromas and hemangioblastomas.

The above lesions are easy to distinguish. Note that normal granule cells look like tumor on smear.

27
Q

What is an acoustic neuroma?

A

A schwannoma arising from the eighth cranial nerve.

28
Q

Describe the appearance and significance of hemangioblastoma.

A

An infratentorial tumor seen in VHL syndrome which resembles CCRCC. Stain for oil red O.

29
Q

Describe the morphology of schwannoma.

A

A benign fibrillary tumor with elongated nuclei of alternating low (antoni A) and high (antoni B) cellularity. Makes palisaded arrays (Verocay bodies)

30
Q

What tumors arise in the midline?

A

Germinoma
Craniopharyngioma
Chordomas

(embryonic remnants)

Pineal and pituitary tumors

31
Q

Describe the appearance of craniopharyngioma.

Which occur in adults?

A

“Adamantinomatous” appearance (looks like developing tooth). Nests of cells boudned by dark palisaded cells, with central areas of stellate cells in a myxoid stroma.

Adults get the papillary type (resembles squamous papilloma)

32
Q

Describe the morphology of chordomas.

A

Bluish, mucinous background like IV discs. Physaliphorous tumor cells full of bubbles and growing in cords.

33
Q

Describe the morphology of pituitary adenoma.

A

Monotonous cells lacking the normal cellular heterogeneity seen in the pituitary. Looks neuroendocrine.

34
Q

Describe the morphology of pineocytoma.

A

Looks like normal pineal gland…

35
Q

What are ependymomas and how are they graded?

A

Usually low-grade (II) lesion of young patients. Can be anaplastic (III).

Subependymomas are lower grade (I).

36
Q

Describe the morphology of ependymoma.

What is a myxopapillary ependymoma?

A

Circumscribed lesion of cells with pale oval nuclei aligned around blood vessels in pseudorosettes.

Myxopapillary: Occurs in filum terminale, with myxoid background and papillary structure.

37
Q

What is subependymal giant cell astrocytoma?

A

A tumor of tuberous sclerosis occurring at the lateral ventricles with very large cell ganglionic appearance.

38
Q

What is central neurocytoma?

A

A low-grade lesion of neural origin, usually involving the third ventricle.

39
Q

Describe the morphology of choroid plexus papilloma / carcinoma.

A

Papilloma: Bland columnar cells forming pseudostratified layers on large arborizing fronds.

Carcinoma: More solid and mitotically active. Invasive.

40
Q

Describe the morphology of medulloblastoma.

A

Sheets of small blue cells. Nuclei resemble small cell carcinoma but can be wedge shaped and in rosettes. Background is fibrillary. Can see differentiated neurons & glia.

41
Q

What do ependymoblastoma, medullomyoblastoma, retinoblastoma, pineoblastoma, neuroblastoma, and medulloblastoma have in common?

A

All have rosette morphology. All are grade IV.

42
Q
A

Astrocytoma, grade II.

Arrows: Irregular and coarse nuclei
Arrowhead: Fibrillary background

43
Q
A

Glioblastoma multiforme

Arrow: Necrosis
Arrowheads: Microvascular proliferation
Inset: Malignant astrocytes with irregular mitoses

44
Q
A

Pilocytic astrocytoma

  1. Fibrillary or hair-like background
  2. Scattered large dark nuclei
  3. Rosenthal fibers
  4. Eosinophilic granular bodies
45
Q
A

Reactive astrocytes

Arrow: Dense pink cytoplasm with stubby processes

46
Q
A

Oligodendroglioma. Note fried-egg cells suspended in a network of fine capillaries (arrow)

47
Q
A

Syncytial meningioma

Arrow: Whorls
Arrowheads: Syncytial groups without cell borders

48
Q
A

Left: Clear cell meningioma. Clear glycogenated cells (arrow).

Right: Rhabdoid meningioma. Plump eosinophilic cells (arrow) resembling skeletal muscle.

49
Q
A

Hemangiopericytoma

Note staghorn vessel in background of small blue cells between epithelioid and spindled in appearance.

50
Q
A

Hemangioblastoma

Note clear lipidized cells with bland nuclei in background of dilated capillaries.

51
Q
A

Schwannoma

A: Antoni A area
B: Antoni B area
Arrow: Verocay bodies

52
Q
A

Craniopharyngioma, adamantinomatous type.

  1. Stellate reticulum
  2. Calcification
  3. Peripheral palisading
  4. “wet” keratin
53
Q
A

Left: Pituitary adenoma. Note monotonous cells. Reticulin negative.

Right: Normal pituitary. Note heterogeneity. Reticulin shows nesting.

54
Q
A

Ependymoma

Arrow: Fibrillary background lining up around vessels. Pseudorosette!

55
Q
A

Myxopapillary ependymoma

Arrow: Papillary fibrovascular core surrounded by myxoid stroma and ependymal cells.

56
Q
A

Medulloblastoma

Small round blue cells with mitoses (arrow) and apoptoses (arrowhead).

Book - Molavi (29 decks)

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