Ch 27-Peripheral Nerve Sheath Tumors

Question 1

The loss of NF2 gene product is ___ which is a consistent finding in all schwannomas. In absence of this gene product, cells hyperproliferate in response to GFs

Answer 1

Merlin

Question 2

The schwann cell origin of schwannomas is borne out by their immunoreactivity for __

Describe if Schwannomas are benign or malignant:

Answer 2

S-100

Benign tumors, malignant transformation is extremely rare

Question 3

___ cause symptoms by local compression of involved nerve or adjacent structures. CPA will present with tinnitus and hearing loss

Answer 3

Schwannomas

Acoustic neuromas

Question 4

This neurofibroma of presents as pedunculated nodules that can be seen isolated (if sporadic) or multiple (NF-1)

Answer 4

Superficial cutaneous

Question 5

This neurofibroma often presents as a large plaquelike elevation of skin and is typically NF-1 associated

Answer 5

Diffuse neurofibroma

Question 6

This neurofibroma is found in deep or superficial locations in association with nerve roots or large nerves and uniformly NF-1 associated

Answer 6

Plexiform neurofibromas

Question 7

In neurofibromas, only the __ cells show complete loss of NF1 gene product, neurofibromin, which is a major tumor suppressor that inhibits RAS activity

Answer 7

Schwann

Question 8

With rare exceptions, transformation to MPNST is only seen in ___ neurofibromas

Answer 8

Plexiform

Question 9

These tumors grow within an expand nerve fascicles, entrapping associated axons. They have an encapsulated appearance and a “bag of worms” appearance is due to expanded, ropy thickening of multiple nerve fascicles

Answer 9

Plexiform neurofibroma

Question 10

This type of tumor has abotu 50% arise in NF1 pts and assumed to result from malignant transformation of a plexiform neurofibroma

Answer 10

MPNST

Question 11

___ is autosomal dominant, 1 in 3000, and caused by loss of function mutations in NF1 gene, located at chr 17q11.2, which encodes the tumor-suppressor Neurofibromin (RAS trapped in active state)

Answer 11

Neurofibromatosis Type 1

Question 12

This tumor presents as a systemic disease associated with nonneoplastic manifestations and with a variety of tumors; other featurs include MR or seizures, skeletal defects, pigmented nodules of the iris (Lisch nodules), and cutaneous hyperpigmented macules (cafe au lait spots)

Answer 12

Neurofibromatosis type 1

Question 13

This tumor is autosomal dominant, 1 in 40,000-50,000, has its gene product on Chr 22q12 of Merlin, which is a cytoskeleton protein that appears to regulate membrane receptor signaling

Answer 13

Neurofibromatosis type 2

Question 14

___ most commonly have bilateral CN VIII schwannomas and multiple meningiomas; can also have gliomas

Answer 14

Neurofibromatosis type 2

Question 15

Schwannomas have this inactivating mutation:

Answer 15

Inactivating mutation in NF2 gene on Chr 22