Meningioma pathophysiology: Difference between revisions

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'''[[Anaplastic]] (Grade III) meningioma'''  
'''[[Anaplastic]] (Grade III) meningioma'''  
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20 or more mitoses/10 HPF, histology similar to [[carcinoma]] or [[sarcoma]]
20 or more mitoses/10 HPF, histology may be similar to [[carcinoma]] or [[sarcoma]]
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[[File:Grade 3 menigioma.jpg|thumb|none|300px|Grade 3 menigioma]]
[[File:Grade 3 menigioma.jpg|thumb|none|300px|Grade 3 menigioma]]

Revision as of 15:06, 28 September 2015

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Haytham Allaham, M.D. [2]

Overview

Meningioma arises from the arachnoid "cap" cells, which are normally involved in the protection of the central nervous system by forming a thick envelope of meninges around the brain and spinal cord.[1][2][3] The majority of meningiomas are benign.[1][2][3] Development of meningioma is the result of multiple genetic mutations.[1] On gross pathology, a gray, well-circumscribed, dome-shaped mass is a characteristic finding of meningioma.[1] On microscopic histopathological analysis, whorled appearance, calcification, and psammoma bodies are characteristic findings of of meningioma.[4]

Pathogenesis

  • Meningioma arises from the arachnoid "cap" cells, which are normally involved in the protection of the central nervous system by forming a thick envelope of meninges around the brain and spinal cord.[1]
  • The majority of meningiomas are benign; however, a minority of cases may develop a malignant nature.[1]
  • The exact pathophysiology of meningioma depends on the histological subtype of the tumor.[1]
  • Meningioma may be located either intradural or extradural along the central nervous system.[5][6]
  • Meningiomas are frequently found attached to the dura surrounding the brain tissue in several locations that include:[1]

Genetics

  • Development of meningioma is the result of multiple genetic mutations.[1]
  • The majority of meningioma cases involve a deletion of the neurofibromatosis 2 gene located on chromosome 22.[1]
  • Other genes involved in the pathogenesis of meningioma include:[1]
  • Protein kinase AKT1 gene located on human chromosome 14
  • Meningioma 1 MN1 gene located on human chromosome 22
  • Phosphatase and tensin homolog PTEN gene located on both human chromosomes 10 and 19
  • SMO gene located on human chromosome 6 and 7

Gross Pathology

  • On gross pathology, a gray, well-circumscribed, dome-shaped mass is a characteristic finding of meningioma.[1]


Gross pathology meningioma[7]

Microscopic Pathology

  • On microscopic histopathological analysis, whorled appearance, calcification, and psammoma bodies are characteristic findings of of meningioma.[4]
  • The table below differentiates between the three main groups of meningioma according to WHO histological classification:[4][2][3]
Grade Histologic features Image

Benign (Grade I) meningioma

Less then 4 mitosis/10 HPF, no atypia

Grade 1 Meningioma

Atypical (Grade II) meningioma

Brain invasion, 4 or more mitosis/10 HPF, necrosis, increased cell count, high nucleus:cytoplasm ratio, increased nucleoli size, presence of sheeting

Grade 2 menigioma

Anaplastic (Grade III) meningioma

20 or more mitoses/10 HPF, histology may be similar to carcinoma or sarcoma

Grade 3 menigioma


  • Demonstrated below is a series of microscopic smears which feature specific findings observed in each subtype of meningioma:[4]

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015
  2. 2.0 2.1 2.2 Meningioma. Canadian Cancer Society http://www.cancer.ca/en/cancer-information/cancer-type/brain-spinal/brain-and-spinal-tumours/meningioma/?region=mb September, 25th 2015
  3. 3.0 3.1 3.2 3.3 Meningeoma. Radiopaedia(2015)http://radiopaedia.org/articles/meningioma Accessed on September, 25th 2015
  4. 4.0 4.1 4.2 4.3 4.4 4.5 Meningioma. Liberpathology(2015) http://librepathology.org/wiki/index.php/Meningioma#Quick_overview accessed on September, 25th 2015
  5. Meningioma diagnosi. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#History_and_nomenclature Accessed on September, 25th 2015
  6. Meningioma. Liberpathology(2015) http://librepathology.org/wiki/index.php/Meningioma#Quick_overview Accessed on September, 25th 2015
  7. Image courtesy of Dr Dharam Ramnani Radiopaedia(original file "here"). Creative Commons BY-SA-NC


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