Ch 21 - Peripheral Nerve Sheath Tumors - DONE Flashcards
What does most of the peripheral nerve sheath tumors show evidence of?
Schwann cell differentiation
Give examples of benign nerve sheath tumors?
- schwanomas
- neurofibromas
Schwannomas
- circumscribed
- usually encapsulated
- most of them are sporadic
- abut the nerve of origin
- are a feature of NF2
NF =
neurofibromas
Neurofibromas
- manifests a sporadic subcutaneous nodule
- large, poorly defined soft tissue lesion, or as a growth within the nerve
- are associated with NF1
peripheral nerve sheath tumors are frequently associated with what?
familial tumor syndromes neurofibromatosis type 1 (NF1) and type 2 (NF2)
Schwannomas location:
- soft tissues
- internal organs
- spinal nerve roots
What is the most commonly affected cranial nerve?
vestibular portions of the eight nerve
Sporadic =
occurring at irregular intervals or only in a few places; scattered or isolated
What are patient with NF2 in risk of developing?
- multiple schwannomas
- miningiomas
- ependydomas
What is a hallmark of NF2?
the presence of schwannomas
Merlin:
is a cytoskeletal protein that functions as a tumor suppressor by facilitating E-cadherin-mediated contact inhibition
What happens with merlin in sporadic schwannomas?
the merlin expression is disrupted
How does the schwannomas appear on microscopic examination?
- 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
Where do we find Antoni A and B?
schwannomas
Where do we find Verocay bodies?
Antoni A -> schwannomas
What are the subtypes of neurofibromas?
- localized cutaneous neurofibromas
- plexiform neurofibromas
- diffuse neurofibromas
Localized cutaneous neurofibromas:
- superficial nodular or polyploid tumors
- occur either as solitary sporadic lesions or as multiple lesions in the context of neurofibromatosis type 1 (NF1)
Plexiform neurofibromas:
- 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
Diffuse neurofibromas:
- infiltrative proliferations
- large disfiguring subcutaneous masses
- associated with NF1
Difference between schwannomas and neurofibromas?
- unlike schwannomas, neurofibromas are not encapsulated
- the cellular growth pattern of neurofibromas are more haphazard than that of schwannomas
Neurofibromas may appear….
- circumscribed, as in localized cutaneous neurofibronas
- or exhibit a diffuse infiltrative growth pattern
Plexiform neurofibromas (morphology):
- 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
Diffuse neurofibromas (morphology):
extensive infiltrative pattern of growth within the dermis and subcutis of the skin
