Wednesday, January 8, 2014

1/8/2013

1/8/2014

Answers:
What percentage of CPA tumors are not vestibular schwannomas?
A) 5% 
B) 20% 
C) 50% 
D) 80% 
E) 95%

20% of CPA tumors are not schwannomas. Of these ~50% are meningiomas.

What factors should prompt testing for NF2 in a patient who presents w/ a CPA tumor?

If meningiomas are present in a young patient or there are multiple meningiomas, then NF2 testing should be considered.

MC Questions:
What is the most common extra-axial malignant neoplasm of the CPA?
A) Astrocytoma 
B) Chordoma 
C) Glomus Jugulare 
D) Chondrosarcoma 
E) Metastases

Free Response Question:
What is "Meckel's Cave"?

Quick Facts:
Neurofibromatosis Type 2
-Hallmark is b/l vestibular schwannomas.
-often confused with von Recklinghausen syndrome, however this is peripheral
neurofibromatosis and is designated NF1.
-NF2 is much more rare compared to NF1 (1:50,000)
-NF2 is autosomal dominant w/ 95% gene penetrance.
-presents in 2-3rd decade.
-Pts w/ NF2 represent 2-4% of VS.
-NF2 gene encodes for protein called merlin which functions as a membrane-organizing protein.
Pathogenesis
-from inheritance of mutation in merlin protein on chromosome 22.
-Merlin involved in linking cytoskeletal components w/ plasma membrane.
-Loss of this protein could lead to loss of contact inhibition.
-50% of patients have no family hx and are likely new germ line mutations.
-NF2 mutations associated w/ protein truncation are more severe = Wishart
type
-NF2 mutations associated w/ protein missense or splicing are milder = Gardner
type

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