Meningioma pathophysiology: Difference between revisions
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==Pathogenesis== | ==Pathogenesis== | ||
Meningioma arises from [[arachnoid]] "cap" cells that compose the [[meninges]], which are normally involved in the protection of the [[central nervous system]] by forming a thick envelope around the [[brain]] and [[spinal cord]]. Meningiomas are usually [[benign]]; however, a small percentage can develop a [[malignant]] nature. The exact pathophysiology of meningioma depends on the histological subtype of the tumor.<ref name="wiki">Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015</ref> Meningiomas are frequently found attached to the [[dura]] surrounding the brain tissue in several locations that include:<ref name="wiki">Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015</ref> | Meningioma arises from [[arachnoid]] "cap" cells that compose the [[meninges]], which are normally involved in the protection of the [[central nervous system]] by forming a thick envelope around the [[brain]] and [[spinal cord]]. Meningiomas are usually [[benign]]; however, a small percentage can develop a [[malignant]] nature. The exact pathophysiology of meningioma depends on the histological subtype of the tumor.<ref name="wiki">Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015</ref> Meningiomas are frequently found attached to the [[dura]] surrounding the brain tissue in several locations that include:<ref name="wiki">Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015</ref> | ||
* [[Frontal lobe]] | * [[Frontal lobe]] | ||
Revision as of 22:15, 24 September 2015
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Meningioma Microchapters |
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Meningioma pathophysiology On the Web |
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American Roentgen Ray Society Images of Meningioma pathophysiology |
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Risk calculators and risk factors for Meningioma pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Haytham Allaham, M.D. [2]
Overview
Pathogenesis
Meningioma arises from arachnoid "cap" cells that compose the meninges, which are normally involved in the protection of the central nervous system by forming a thick envelope around the brain and spinal cord. Meningiomas are usually benign; however, a small percentage can develop a malignant nature. The exact pathophysiology of meningioma depends on the histological subtype of the tumor.[1] Meningiomas are frequently found attached to the dura surrounding the brain tissue in several locations that include:[1]
- Frontal lobe
- Parietal lobe
- Brain convexity
- Sphenoid ridge
- Sella turcica
- Posterior fossa
- Olfactory groove
- Meckel's cave
- Tentorium cerebelli
- Confluence of sinuses
Genetics
- Development of meningioma is the result of multiple genetic mutations.[1]
- The most common gene involved in the pathogenesis of meningioma is 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]
Microscopic Pathology
- On microscopic histopathological analysis, whorled appearance, calcification, and psammoma bodies are characteristic findings of of meningioma.[2]
- The table below differentiates between the three main groups of meningioma according to WHO histological classification:[2][3][4]
| Grade | Histologic features | Image |
|---|---|---|
|
Benign (Grade I) 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 |
 |
|
Anaplastic (Grade III) meningioma |
20 or more mitoses/10 HPF, histology similar to carcinoma or sarcoma |
 |
- Shown below is a series of microscopic images featuring specific findings seen in each subtype of meningioma:[2]
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A smear showing meningothelial meningioma with syncytial appearance and whorl formation
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A smear showing meningothelial meningioma with onion bulb formation
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A smear showing meningothelial meningioma HPS stain
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A smear showing fibrous meningioma with spindle cells in parallel bundles
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A smear showing fibrous meingioma on EMA stain
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A smear showing transitional meningioma with coexisting lobular and fasicular growth patterns
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A smear showing psammomatous meningioma with numerous psammoma bodies
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A smear showing angiomatous meningioma with hyalinized vessels
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A smear showing microcystic meningioma with cystic appearance and increased pleomorphism of the elongated cells
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A smear showing secretory meningioma with secretory granules
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A smear showing secretory meningioma with PAS stain positive secretory granules
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A smear showing chordoid meningioma with myxoid appearance
-
-
A smear showing rhabdoid meningiomao with abundant cytoplasm and cross-striations
_transitional_type.jpg)
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Meningioma. Wikipedia(2015) https://en.wikipedia.org/wiki/Meningioma#cite_note-pmid7731706-9 Accessed on September, 25th 2015
- ↑ 2.0 2.1 2.2 Meningioma. Liberpathology(2015) http://librepathology.org/wiki/index.php/Meningioma#Quick_overview accessed on September, 25th 2015
- ↑ 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
- ↑ Meningeoma. Radiopaedia(2015)http://radiopaedia.org/articles/meningioma Accessed on September, 25th 2015