Schwannoma pathophysiology: Difference between revisions

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==Pathophysiology==
==Pathophysiology==


* Unilateral schwannomas are usually sporadic.
===Spontaneous===
* Bilateral schwannomas are associated with Neurofibromatosis type 2.
** Allelic inactivation of NF2 gene involving a point mutation or multiexon deletion in second point mutation or loss of heterozygosity. <ref name="pmid20729918">{{cite journal |vauthors=Hadfield KD, Smith MJ, Urquhart JE, Wallace AJ, Bowers NL, King AT, Rutherford SA, Trump D, Newman WG, Evans DG |title=Rates of loss of heterozygosity and mitotic recombination in NF2 schwannomas, sporadic vestibular schwannomas and schwannomatosis schwannomas |journal=Oncogene |volume=29 |issue=47 |pages=6216–21 |date=November 2010 |pmid=20729918 |doi=10.1038/onc.2010.363 |url=}}</ref>
 
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==Genetics==
==Genetics==
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# Direct genetic change involving the ''NF2'' gene on chromosome 22
# Direct genetic change involving the ''NF2'' gene on chromosome 22
# Secondary to merlin inactivation <ref name="pmid25893302">{{cite journal |vauthors=Petrilli AM, Fernández-Valle C |title=Role of Merlin/NF2 inactivation in tumor biology |journal=Oncogene |volume=35 |issue=5 |pages=537–48 |date=February 2016 |pmid=25893302 |pmc=4615258 |doi=10.1038/onc.2015.125 |url=}}</ref><br />
# Secondarily to merlin inactivation<br />


==Associated Conditions==
==Associated Conditions==
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==Immunohistochemistry==
==Immunohistochemistry==
Positive for:
*S100
*Collagen IV
*CD34
*Neurofilament protein
*Podoplanin
*Calretinin
*Sox10
Negative for:
*EMA


==References==
==References==

Revision as of 00:05, 28 October 2019


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:  ; Maneesha Nandimandalam, M.B.B.S.[2]

Overview

Pathophysiology

Spontaneous


Genetics

  • Loss of function of a tumor suppressor gene called merlin gene, either by:
  1. Direct genetic change involving the NF2 gene on chromosome 22
  2. Secondarily to merlin inactivation

Associated Conditions

  • Neurofibromatosis type 2 (NF2)[1]
  • Schwannomatosis
  • Carney's complex

Gross and Microscopic Pathology

Microscopic appearance

  • Conventional schwannomas are composed of spindle cells which demonstrate two growth patterns: Antoni type A and Antoni type B 7,8.[2][3][4]
  • Antoni type A pattern: elongated cells are densely packed and arranged in fascicles. Palisades are sometimes seen; when prominent these form Verocay bodies.
  • Antoni type B pattern cells are less compact and are prone to cystic degeneration.
Variants

Schwannoma variants include 6,8:

  • ancient schwannoma
  • cellular schwannoma
    • predominantly composed of Antoni A tissue
    • no Verocay bodies
    • most commonly found in a paravertebral location, or trigeminal nerves (CN V)
  • melanotic schwannoma: dense melanin pigment
  • plexiform schwannoma[5]
    • usually arise from skin or subcutaneous tissues
    • usually diagnosed at birth or childhood
    • usually sporadic, but rarely associated with NF2
    • should not be confused with plexiform neurofibromas
      • associated with NF1
      • may undergo malignant change

Immunohistochemistry

Positive for:

  • S100
  • Collagen IV
  • CD34
  • Neurofilament protein
  • Podoplanin
  • Calretinin
  • Sox10

Negative for:

  • EMA

References

  1. Hilton DA, Hanemann CO (April 2014). "Schwannomas and their pathogenesis". Brain Pathol. 24 (3): 205–20. doi:10.1111/bpa.12125. PMID 24450866.
  2. Doddrell RD, Dun XP, Shivane A, Feltri ML, Wrabetz L, Wegner M; et al. (2013). "Loss of SOX10 function contributes to the phenotype of human Merlin-null schwannoma cells". Brain. 136 (Pt 2): 549–63. doi:10.1093/brain/aws353. PMC 3572932. PMID 23413263.
  3. Sayed SI, Rane P, Deshmukh A, Chaukar D, Menon S, Arya S; et al. (2012). "Ancient schwannoma of the parapharynx causing dysphagia: a rare entity". Ann R Coll Surg Engl. 94 (7): e217–20. doi:10.1308/003588412X13373405385737. PMC 3954264. PMID 23031754.
  4. Giovannini M, Bonne NX, Vitte J, Chareyre F, Tanaka K, Adams R; et al. (2014). "mTORC1 inhibition delays growth of neurofibromatosis type 2 schwannoma". Neuro Oncol. 16 (4): 493–504. doi:10.1093/neuonc/not242. PMC 3956353. PMID 24414536.
  5. Tchernev G, Chokoeva AA, Patterson JW, Bakardzhiev I, Wollina U, Tana C (February 2016). "Plexiform Neurofibroma: A Case Report". Medicine (Baltimore). 95 (6): e2663. doi:10.1097/MD.0000000000002663. PMC 4753888. PMID 26871793.

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