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Pathomorph - CREDIT 2 > Ch 21 - Peripheral Nerve Sheath Tumors - DONE > Flashcards

Ch 21 - Peripheral Nerve Sheath Tumors - DONE Flashcards

1
Q

What does most of the peripheral nerve sheath tumors show evidence of?

A

Schwann cell differentiation

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2
Q

Give examples of benign nerve sheath tumors?

A
  • schwanomas

- neurofibromas

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3
Q

Schwannomas

A
  • circumscribed
  • usually encapsulated
  • most of them are sporadic
  • abut the nerve of origin
  • are a feature of NF2
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4
Q

NF =

A

neurofibromas

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5
Q

Neurofibromas

A
  • manifests a sporadic subcutaneous nodule
  • large, poorly defined soft tissue lesion, or as a growth within the nerve
  • are associated with NF1
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6
Q

peripheral nerve sheath tumors are frequently associated with what?

A

familial tumor syndromes neurofibromatosis type 1 (NF1) and type 2 (NF2)

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7
Q

Schwannomas location:

A
  • soft tissues
  • internal organs
  • spinal nerve roots
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8
Q

What is the most commonly affected cranial nerve?

A

vestibular portions of the eight nerve

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9
Q

Sporadic =

A

occurring at irregular intervals or only in a few places; scattered or isolated

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10
Q

What are patient with NF2 in risk of developing?

A
  • multiple schwannomas
  • miningiomas
  • ependydomas
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11
Q

What is a hallmark of NF2?

A

the presence of schwannomas

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12
Q

Merlin:

A

is a cytoskeletal protein that functions as a tumor suppressor by facilitating E-cadherin-mediated contact inhibition

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13
Q

What happens with merlin in sporadic schwannomas?

A

the merlin expression is disrupted

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14
Q

How does the schwannomas appear on microscopic examination?

A
  • they often show an admixture of dense and loose areas referred to as Antoni A and B, respectively
  • Verocay bodies in Antoni A
  • hemorrhages and cystic change are also seen sometimes
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15
Q

Where do we find Antoni A and B?

A

schwannomas

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16
Q

Where do we find Verocay bodies?

A

Antoni A -> schwannomas

17
Q

What are the subtypes of neurofibromas?

A
  • localized cutaneous neurofibromas
  • plexiform neurofibromas
  • diffuse neurofibromas
18
Q

Localized cutaneous neurofibromas:

A
  • superficial nodular or polyploid tumors

- occur either as solitary sporadic lesions or as multiple lesions in the context of neurofibromatosis type 1 (NF1)

19
Q

Plexiform neurofibromas:

A
  • grow diffusely within the confines of a nerve or nerve plexus
  • surgical enucleation is difficult
  • associated with lasting neurologic deficit
  • virtually pathognomonic for NF 1
  • small but real risk of malignant transformation
20
Q

Diffuse neurofibromas:

A
  • infiltrative proliferations
  • large disfiguring subcutaneous masses
  • associated with NF1
21
Q

Difference between schwannomas and neurofibromas?

A
  • unlike schwannomas, neurofibromas are not encapsulated

- the cellular growth pattern of neurofibromas are more haphazard than that of schwannomas

22
Q

Neurofibromas may appear….

A
  • circumscribed, as in localized cutaneous neurofibronas

- or exhibit a diffuse infiltrative growth pattern

23
Q

Plexiform neurofibromas (morphology):

A
  • involve multiple fascicles of individual affected nerves
  • residual axons are found embedded within the diffuse neuplastic Schwann cell proliferation, which expand the fascicles while leaving the perineurium intact
24
Q

Diffuse neurofibromas (morphology):

A

extensive infiltrative pattern of growth within the dermis and subcutis of the skin

25
Q

How can the malignant peripheral nerve sheath tumors arise from?

A

neurofibroma, usually of the plexiform type

26
Q

malignant peripheral nerve sheath tumors (morphology)

A
  • large, poorly defined soft tissue masses
  • highly cellular and exhibit features of overt malignancy, including anaplasia, necrosis, infiltrative growth pattern, pleomorphism, and high proliferative activity
  • marble-like
  • perivascular areas of increased cellular density
27
Q

NF1

A
  • autosomal dominant disorder
28
Q

What causes NF1?

A
  • mutation in the tumor suppressor neurofibromin, encoded on the long arm of chromosome 17 (17q)
29
Q

What is neurofibromin?

A

a negative regulator of the potent oncoprotein Ras

30
Q

What is a cardinal feature of NF1-associated tumors

A

disruption of the neurofibromin function and Ras hyperactivity

31
Q

What does those with NF1 exhibit:

A
  • learning disabilities
  • seizures
  • skeletal abnormalities
  • vascular abnormalities with arterial stenosis
  • pigmented nodules of the iris (Lisch nodules)
  • pigmented skin lesions (axillary freckling and cafe au lait spots) in various degrees
32
Q

What is traumatic neuroma?

A

non-neoplastic proliferation associated with previous injury of a peripheral nerve

Pathomorph - CREDIT 2 (9 decks)

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