Astrocytic Tumors

8/7/2019 Astrocytic Tumors

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Astrocytic Tumors

An informative slide show


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What are astrocytic tumors?

Astrocytic tumors refer to tumors that arise fromthe nervous system. These tumors begin in cellscalled astrocytes, which are are star-shaped braincells that help keeps nerve cells healthy.Astrocytes are a type of glial cell. Glial cells aresupportive cells for the neurons; astrocytes

primarily deal with maintaing neuronal metabolismand neurotransmission.


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Astrocyte


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Classification

Astrocytic tumors encompass a wide variety of cells thataffect both te central and peripheral nervous system. Whenthe World Health Organization (WHO) refers to astrocytic

tumors, they typically categorize the tumors into thesegroups:

Pilocytic Astrocytoma (WHO Grade I)

Pleomorphic Xanthoastrocytoma (WHO Grade II)

Diffuse Astrocytoma (WHO Grade II)

Anaplastic Astrocytoma (WHO Grade III)

Glioblastoma (WHO Grade IV)


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Pilocytic Astrocytoma

Pilocytic astrocytomas are tumors that are relatively slowgrowing tumors that are typically found in younger people.Pilocytic astrocytomas are tumors that are composed of cells

that are associated with Rosenthal fibers, giving them thename pilocytic (Cells that look as if they are composed fromhair).

Locations

Pilocytic astrocytomas are most commonly located in thecerebellum of children, with rare cases of these tumors inelderly patients.


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Pilocytic Astrocytomas

Symptoms

Headaches, hormone imbalances and intracranial pressureare typical symptoms. Due to the slow growing nature of

pilocytic astrocytomas, the tumors appear to be lesions that

are gradually evolving.

Histology

The majority of astrocytic tumors are soft, grey and seperate.Other characteristics are the formation of cysts, necrosis andcalcification.


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Pilocytic Astrocytomas

CytologyThe cells often contain round or oval nuclei, a modest sizeand small network process.

Rosenthal fibers can also be found in pilocytic astroctyomas.

These tumors are also very vascular, with possible regressivechanges.

Prognosis

The prognosis for pilocytic astrocytomas is typically a long

life, which may result in death after a long period of time.Particular problems may arise when dealing with tumorslocated in the brain stem or hypothalamus. However, mostpeople diagnosed with this tumor typically survive muchlonger than those with other tumors of the nervous system.


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Pilocytic Astrocytoma


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Pleomorphic Xanthoastrocytoma

Pleomorphic Xanthoastrocytomas are tumors with a WHOgrade of II.

Occurence

Less than 1% of astrocytic tumors are caused by pleomorphicxanthoastrocytomas. The majority, about two-thirds, of thesecases occur in those under age 18, but there have beenreports of the elderly being afflicted also.

Locations

Typically, the outer surface of the brain is affected,particularly the meninges and cerebrum. Also, about 98% ofall cases were located above the spinal cord and cerebellum.

The majority were found in the temporal lobe.


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Symptoms

Seizures are typical of those diagnosed with pleomorphicxanthoastrocytoma. These tumors are attached to the

meninges and can be accompanied by a cyst. Their locationare the causes for the seizures.

Histopathology

As the name "pleomorphic" suggests, these tumors arecapable of taking many shapes, including a large variation incomposition, number of nuclei per cell, staining and size. Theuse of the word "xantho" refers to the build up of fat depositslittered throughout the tumor.


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Prognosis

While there is little evidence of genetic suspectiblity, there arestudies that show that pleomorphic xanthoastrocytomas can

be caused by additions or subtractions of chromosomesand/or genes. However, there is hope for those diagnosedwith this tumor. Even though the neoplasm can give rise to amultitude of shapes, it's not as malignant as otherpleomorphic tumors. Approximately 70% of those who havethis tumor survive past ten years.


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Diffuse Astrocytoma

A diffuse astrocytoma is a tumor that can arise fromastrocytes, and instead of staying concentrated in one spot, itspreads and penetrates throughout the brain.

Occurence

Out of all neoplasms arising from astrocytes, the diffuseastrocytoma accounts for approximately 10-15%. Thisastrocytoma usually strikes young adults, with a predominantdisplay in the 30-39 range, for both males and females.However, only about 1.4 new cases are shown for every 1

million people per year.

Symptoms

Seizures, personality changes, and more subtle changes,such as vision or motor problems are all symptoms. This isdue to the localization of the tumors.


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Diffuse Astrocytoma

Appearance

Diffuse astrocytomas appear on CT scans as a mass ofidentical cells. It is possible to see other changes, such as

cysts or calcification. Unfortunately, the penetrating nature ofthis tumor means that anatomically the boundary betweencancerous and normal tissue is hard to define. Instead ofdestruction, this tumor tends to enlarge and warp the shapeand size of the area it effects. Both multiple microcysts or onelarge cysts is possible to be noted of, which can change thetexture and appearance of the tumor.


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Diffuse AstrocytomaFibrillary Astrocytoma

Of the three types of diffuse astroctyomas, the fibrillary astrocytma isthe most common. It's composed of cells with quantities of minutefibers, or fibrils. Hence the name, fibrillary. Some of the ways todiagnose this tumor is by the presence of abnormal nuclei, moderatecell density, rare miotitc divisions, and an abundance of microcysts.

Gemistocytic Astrocytoma

This tumor is noted to contain gemistocytic astrocytes, which areplump cells, due to an abundance of cytoplasm, nuclear atypia andglial filaments. These tumors are inclined to turn into anaplastic

astrocytomas, and ultimately glioblastomas.

Protoplasmic Astrocytomas

A rare form of diffuse astrocytomas, small cell bodies, few filaments,and minimal GFAP presentation are typical for this type of tumor.


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Diffuse Astrocytoma

Prognosis

While always dependent on the individual, most statisticsshow people living up to 6-8 years after diagnosis of a diffuse

astrocytoma. After about 4-5 years, this tumor usuallydescends into a glioblastoma. A more positive prognosis isgiven to younger patients, but the size of the tumor can alsobe a factor, typically the larger in size, the more likely tospeed into a glioblastoma.


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Diffuse Astrocytoma


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Anaplastic Astrocytoma

Anaplastic Astrocytomas are WHO grade III tumors.Anaplasia is a distinctive feature, which means that the cellsare lacking differentiation. These tumors are malignant

astrocytomas that are noted by extensive infiltration,abnormal nuclei, increased spreading and heightenedconcentrations of cells. These tumors can arise from eitherdiffuse astrocytomas or without any precursor tumors.

Occurence

These neoplasms afflict middle aged men the most, with amean age of 45 years old. Also, men are slightly moreaffected than women. Similar to diffuse astrocytomas, thecerebral lobes are the most commonly affected.


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Anaplastic Atrocytoma

Symptoms

The symptoms are similar to diffuse astrocytomas, with anincrease in neurological problems, such as pressure, seizures

or other problems, like vision or motor issues.

Appearance

Instead of destruction, anaplastic astrocytomas prefer toinfiltrate tissues surrounding the tumor, causing enlargement

of the affected tissues. Grossly, it is difficult to tell thedifference between an anaplastic astrocytoma or a diffuseastrocytoma. Increased cellularity and tumor size are themain markers when viewing at a macroscopic level.


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HistopathologyWhen viewing the neoplasm at a microscopic level, thecharacteristics of an anaplastic astrocytoma are discernibleabnormalaties in the nuclei and mitotic activity. The increased

mitotic activity is particularly noted, because in comparison tomany of the other types of brain tumors, mitotic activity isnoted primarily in anaplastic astrocytomas and glioblastomas.

Prognosis

Two years is the typical estimate for those diagnosed withanaplastic astrocytoma, but this is primarly due to thetendency of progression towards a glioblastoma. Typical ofmany diseases, elderly patients afflicted by this neoplasmusually have a worse prognosis.


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GlioblastomaBoth the most common and most malignant brain tumor

arising from astrocytes, the characteristics of a glioblastoma(GBM) are abnormal nuclei, many different cell forms,increased reproduction of cells, blood clots, multiudes ofblood vessels and tissue death. The primary demographicaffected by GBMs are elderly individuals.

Occurence

Accounting for approximately 15% of all brain tumors, and 60-75% of all astrocytic tumors, there are about 3-4 cases of

GBM for every 100,000 individuals per year. The average ageof those afflicted with a glioblastoma is approximately 60years old, with men being slightly more prone than women.The cerebral hemispheres (temporal, parietal, front, andoccipital lobes) are the primary source of these tumors.


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Glioblastoma

Symptoms

Symptoms arising from a glioblastoma are similar to otherbrain tumors, with headache, nausea, epileptic seizures andpersonality changes being typical. Strokes, or similar

phenomenon, can also occur.

Appearance

The tumors are large, and can easily be the size of an entirelobe. Typically, the neoplasm is the same throughout, with

little differentiation shown. The tumor is typically grey, withsome yellow areas due to fat necrosis. The hyperceullarity, orvast amount of cells, cause the tumor itself to be soft mass.However, necrosis can change both shape, texture and colorof the tumor.


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Glioblastoma

GrowthGlioblastomas are well known for their ability and tendency tospread quickly through the brain, particularly into thestructures of the brain (lobes). While the tumor can spread in

many directions and form many different shapes, the mass isconnected, so new tumor masses can be formed all acrossthe brain, creating what appears to multiple center points ofcancerous growth. Due to the nature of the GBM, it doesn'ttypically infiltrate the brain fluid, so the tumor doesn't

metastasize. Certain genes in a glioblastoma can helpinfiltration through the extracellular matrix when activated.There is speculation when it comes to multiple centers ofgrowth. While it appears as if there are multiple tumors, it mayin fact be just one spread out across the brain.


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Glioblastoma

HistopathologyGlioblastomas are made up of poorly differentiated cells thatare quickly undergoing mitosis. Also, dead tissue (necrosis)and increased concentration of blood vessels are importantfor diagnosing a GBM. These tumors can take many differentforms, giving it the synonymous name "GlioblastomaMultiforme". Epethelial tissue is not uncommon. Anothercharacteristic of a glioblastoma is the presence ofmultinucleated giant cells, along with gemistocytes and

granular cells. While lipidized cells (cells with a high fatcontent), perivascular lymphocytes (a white blood cell foundnear blood vessels), and metaplasia (differentiation of cells,as compared to anaplasia) are found in a few cases ofglioblastoma, the appearance of an abundance of small blood

vessels is imperative to the labeling of a glioblastoma.


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GlioblastomaPrognosis

Unfortunately, the prognosis of an individual with glioblastoma isvery grim. Studies based in Switzerland and Canada show thatless than 20% of patients survive longer than a year, and less than3% survive past three years. Age is the biggest factor, with

younger patients facing a much better prognosis than elderlyvictims.

Treatment

Treating a glioblastoma is a very tough challenge. There is typicallylittle difference in prognosis even after aggresive treatment, usingradiation, surgery, etc. Problems arise due to the blood brainbarrier, lack of response due to vast changes in genomicinformation and spread of the tumor to nearly every part of thebrain, including the brain stem. In order to full combat aglioblastoma, a wide range of medicines would have to be used to

counter all of the defects of the tumor cells.


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Glioblastoma


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Glioblastoma

The pictures below are from my mentorship,taken from an older female with a GBM.

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Astrocytic Tumors