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== Genetic ==
== Genetic ==
* One the most common causes of acoustic neuroma is [[Neurofibromatosis type II|neurofibromatosis type 2 (NF2)]].
* One the most common causes of acoustic neuroma is [[Neurofibromatosis type II|neurofibromatosis type 2 (NF2)]], an [[Dominance relationship|autosomal dominant]] disease caused by loss of function [[Mutation|mutation]].  
* [[Neurofibromatosis type II|Neurofibromatosis Type 2]] is an [[Dominance relationship|autosomal dominant]] disease caused by loss of function [[Mutation|mutations]]. 
* Approximately 50% of reported NF2 cases represent new mutations for which no other affected family member can be identified.
* NF2 [[gene]] is on [[chromosome]] 22q12.2 that encodes a 595–[[amino acid]] [[protein]] named “moesin- ezrin-radixin–like protein,” otherwise known as “merlin” or “schwannomin.”<ref>{{Cite journal
| author = [[Michael E. Sughrue]], [[Andrea H. Yeung]], [[Martin J. Rutkowski]], [[Steven W. Cheung]] & [[Andrew T. Parsa]]
| title = Molecular biology of familial and sporadic vestibular schwannomas: implications for novel therapeutics
| journal = [[Journal of neurosurgery]]
| volume = 114
| issue = 2
| pages = 359–366
| year = 2011
| month = February
| doi = 10.3171/2009.10.JNS091135
| pmid = 19943731
}}</ref>
* Merlin protein linked with other proteins in [[Cell (biology)|cell]] and are involved in linking [[Cytoskeleton|cytoskeletal]] components with the [[Cell membrane|plasma membrane]] and are located in actin-rich surface projections such as [[Microvillus|microvilli]], membrane surfaces, and cell contact regions.
* [[Dephosphorylation|Dephosphorylated]] Merlin proteins are active and roll in the normal [[cell growth]], [[Phosphorylation|phosphorylated]] Merlin ( [[Chemical synthesis|synthesized]] due to a [[mutation]] in NF2 [[gene]] that causes to produce a truncated Merlin protein) inactivated and can not play normal roll in [[cell growth]] and causes increased [[cell growth]].<ref name=":0">{{Cite journal|last=Wippold II|first=F.J|date=2007|title=Neuropathology for the Neuroradiologist: Antoni A and Antoni B Tissue Patterns|url=|journal=AJNR Am J Neuroradiol|volume=|pages=|via=}}</ref><ref>{{Cite journal|last=SUGHRUE|first=MICHAEL E.|date=2011|title=Molecular biology of familial and sporadic vestibular schwannomas: implications for novel therapeutics|url=|journal=J Neurosurg|volume=114|pages=|via=}}</ref>


== Associated Conditions ==
== Associated Conditions ==
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  | pmid = 6850504
  | pmid = 6850504
}}</ref>
}}</ref>
*Exposure to high-dose ionizing radiation is the only definite environmental risk factor associated with an increased risk of developing an acoustic neuroma.<ref>{{Cite journal
*Exposure to high-dose [[ionizing radiation]] is the only definite environmental risk factor associated with an increased risk of developing an acoustic neuroma.<ref>{{Cite journal
  | author = [[Oyebode Taiwo]], [[Deron Galusha]], [[Baylah Tessier-Sherman]], [[Sharon Kirsche]], [[Linda Cantley]], [[Martin D. Slade]], [[Mark R. Cullen]] & [[A. Michael Donoghue]]
  | author = [[Oyebode Taiwo]], [[Deron Galusha]], [[Baylah Tessier-Sherman]], [[Sharon Kirsche]], [[Linda Cantley]], [[Martin D. Slade]], [[Mark R. Cullen]] & [[A. Michael Donoghue]]
  | title = Acoustic neuroma: potential risk factors and audiometric surveillance in the aluminium industry
  | title = Acoustic neuroma: potential risk factors and audiometric surveillance in the aluminium industry
Line 95: Line 79:
  | pmid = 15515018
  | pmid = 15515018
}}</ref>
}}</ref>
*Acoustic neuroma is strongly associated with [[Neurofibromatosis type II|neurofibromatosis type 2 (NF2)]].


==Microscopic Pathology==
==Microscopic Pathology==
* In 1920, Nils Ragnar Euge`ne Antoni (1887–1968), a Swedish neurologist and researcher described 2 distinct patterns of cellular architecture in the peripheral [[Nerve sheath tumor|nerve sheath tumors]], based his observations on analysis of 30 cases and described a “fibrillary, intensely polar, elongated appearing tissue type” which he called “tissue type A.” <ref name=":0" />
* In 1920, Nils Ragnar Euge`ne Antoni (1887–1968), a Swedish neurologist and researcher described 2 distinct patterns of cellular architecture in the peripheral [[Nerve sheath tumor|nerve sheath tumors]], based his observations on analysis of 30 cases and described a “fibrillary, intensely polar, elongated appearing tissue type” which he called “tissue type A.” <ref name=":0">{{Cite journal|last=Wippold II|first=F.J|date=2007|title=Neuropathology for the Neuroradiologist: Antoni A and Antoni B Tissue Patterns|url=|journal=AJNR Am J Neuroradiol|volume=|pages=|via=}}</ref>
* These highly cellular regions were eventually referred to as Antoni A regions by later authors. <ref name=":0" />
* These highly cellular regions were eventually referred to as Antoni A regions by later authors. <ref name=":0" />
* Antoni also described seemingly distinct loose microcystic tissue adjacent to the Antoni A regions, and these came to be known as Antoni B regions.<ref name=":0" />
* Antoni also described seemingly distinct loose microcystic tissue adjacent to the Antoni A regions, and these came to be known as Antoni B regions.<ref name=":0" />

Revision as of 18:21, 22 April 2019

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2] Mohsen Basiri M.D.

Overview

Acoustic neuroma arises from Schwann cells, which are the cells involved in the conduction of nervous impulses along axons, nerve development and regeneration. On microscopic histopathological analysis, acoustic neuroma may display two types of growth patterns: Antoni type A and Antoni type B. Antoni type A growth pattern is composed of elongated cells with cytoplasmic processes arranged in fascicles, little stromal matrix and verocay bodies. Antoni type B growth pattern is composed of loose meshwork of cells, less dense cellular matrix, microcysts and myxoid change.

Pathophysiology

Genetic

Associated Conditions

Microscopic Pathology

  • In 1920, Nils Ragnar Euge`ne Antoni (1887–1968), a Swedish neurologist and researcher described 2 distinct patterns of cellular architecture in the peripheral nerve sheath tumors, based his observations on analysis of 30 cases and described a “fibrillary, intensely polar, elongated appearing tissue type” which he called “tissue type A.” [7]
  • These highly cellular regions were eventually referred to as Antoni A regions by later authors. [7]
  • Antoni also described seemingly distinct loose microcystic tissue adjacent to the Antoni A regions, and these came to be known as Antoni B regions.[7]

They can display two types of growth patterns:[7]

  • Antoni A
  • Antoni B
    • Loose meshwork of cells
    • Less densely cellular
    • Microcysts and myxoid change
  • Photomicrograph of Antoni A tissue and Antoni B tissue within a schwannoma. The highly cellular Antoni A region on the right of the field is contrasted with the loosely organized hypocellular Antoni B region on left of the field (hematoxylin-eosin, original magnification 400).
Photomicrograph of Antoni A tissue and Antoni B tissue within a schwannoma. The highly cellular Antoni A region on the right of the field is contrasted with the loosely organized hypocellular Antoni B region on left of the field (hematoxylin-eosin, original magnification 400).
Photomicrograph of Antoni A tissue and Antoni B tissue within a schwannoma. The highly cellular Antoni A region on the right of the field is contrasted with the loosely organized hypocellular Antoni B region on left of the field (hematoxylin-eosin, original magnification 400). 

References

  1. Acoustic Schwannoma. Radiopedia(2015) http://radiopaedia.org/articles/acoustic-schwannoma Accessed on October 2 2015
  2. Arthur B. Schneider, Elaine Ron, Jay Lubin, Marilyn Stovall, Eileen Shore-Freedman, Jocelyn Tolentino & Barbara J. Collins (2008). "Acoustic neuromas following childhood radiation treatment for benign conditions of the head and neck". Neuro-oncology. 10 (1): 73–78. doi:10.1215/15228517-2007-047. PMID 18079359. Unknown parameter |month= ignored (help)
  3. E. Shore-Freedman, C. Abrahams, W. Recant & A. B. Schneider (1983). "Neurilemomas and salivary gland tumors of the head and neck following childhood irradiation". Cancer. 51 (12): 2159–2163. PMID 6850504. Unknown parameter |month= ignored (help)
  4. Oyebode Taiwo, Deron Galusha, Baylah Tessier-Sherman, Sharon Kirsche, Linda Cantley, Martin D. Slade, Mark R. Cullen & A. Michael Donoghue (2014). "Acoustic neuroma: potential risk factors and audiometric surveillance in the aluminium industry". Occupational and environmental medicine. 71 (9): 624–628. doi:10.1136/oemed-2014-102094. PMID 25015928. Unknown parameter |month= ignored (help)
  5. Mantao Chen, Zuoxu Fan, Xiujue Zheng, Fei Cao & Liang Wang (2016). "Risk Factors of Acoustic Neuroma: Systematic Review and Meta-Analysis". Yonsei medical journal. 57 (3): 776–783. doi:10.3349/ymj.2016.57.3.776. PMID 26996581. Unknown parameter |month= ignored (help)
  6. L. Magnus Backlund, Dan Grander, Lena Brandt, Per Hall & Anders Ekbom (2005). "Parathyroid adenoma and primary CNS tumors". International journal of cancer. 113 (6): 866–869. doi:10.1002/ijc.20743. PMID 15515018. Unknown parameter |month= ignored (help)
  7. 7.0 7.1 7.2 7.3 Wippold II, F.J (2007). "Neuropathology for the Neuroradiologist: Antoni A and Antoni B Tissue Patterns". AJNR Am J Neuroradiol.


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