Neuroepithelial Tumors: Astrocytoma

by Carlo Raj, MD

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    00:00 Our topic here is neuroepithelial tumor. To begin with, where are we in terms of organization? Primary metastasis, this is primary CNS tumor. Under primary CNS tumor, we're looking at neuroepithelial tumor. The classification of neuroepithelial tumor will be your astrocytic or astrocytomas. Let's take a look. Definition - tumor derived from, as you can imagine, astrocytes. You think of this as being glial cells and how often have you come across. A description, a reading or a narration or let's say a CPC, a pathologic conference in which you're sitting around and you hear the term glioma. Right? Well, this is what we're referring to. So the fact that you have an astrocytoma, please be aware that anatomically the glial cells and at some point these would then be referred to as being gliomas. The types, we'll take a look at low grade astrocytoma. Anaplastic is never a good thing. Glioblastoma multiforme, we'll be spending time with this one in great detail and the reason for that is it is one of the most common, unfortunate, brain tumors that occurs in adults but really could be seen across the spectrum. Then we have A astrocytoma that occurs almost exclusively in children and this is then referring to your pilocytic astrocytoma and you will be focusing upon the cytic and I'll tell you why in a bit. And then you can have your, what's known as your pleomorphic xanthoastrocytoma. Let's take a look at astrocytoma further and under here 80% of adult primary brain tumors will be an astrocytoma. That's how important these gliomas are. 80% of adult primary brain tumor, you want to put yourself into the category of astrocytomas.

    02:11 That will be your fibrillary anaplastic or glioblastoma multiforme. Usually arise in the cerebral hemisphere as you can imagine because we're not dealing with our meninges.

    02:23 Usually presents with, as you can imagine, once again the brain parenchyma so therefore perhaps focal neurologic deficit, maybe there's headache and maybe there's new onset seizures. This is an important point, pay attention to the clinical presentation, understand why this will be seen because we're referring to the brain parenchyma. Pathogenesis, inactivation of P53. As soon as you have P53 that has been knocked out and really nothing that is modulating or regulating your cell cycle and so therefore the cell is allowed to remain within the cell cycle forever and so therefore may then result in increased proliferation. Please note overexpression of platelet derived growth factor A or alpha PDGF, memorize that please for astrocytoma specifically aka gliomas and here we have adult.

    03:15 You'll notice here that the astrocytoma that's missing in adult primary brain tumor is which one, pilocytic. Let's talk about the gross examination of your brain tumors. The one that you want to pay attention to. Here is what was glioblastoma multiforme, areas are firm and white or soft and yellow areas representing your areas of necrosis. And what's dangerous about glioblastoma is either one you are trying to surgically correct it, there is every possibility that these will then come back and in addition this particular neoplastic cells will then seed, in terms of spread, and by seeding we mean it is then going to pop into adjacent structures, maybe perhaps even your cerebrospinal fluid. Microscopically, fibrillary, mild to moderate increase in number of glial cell nuclei. That should make perfect sense.

    04:20 This is an absolute malignancy and this is an astrocytic origin and so therefore we expect the nuclear cytoplasm place you to be, quite high. Extreme activity in the nucleus. We have nuclear pleomorphism intervening what's known as feltwork and make sure that you memorize GFAP. With anaplastic, what does that mean to you? Hmm, complete chaos is taking place within the nuclei. So increased cellularity and nuclear pleomorphism beyond belief. Marked mitotic activity. Anaplastic, complete, complete poor prognosis. And then we have glioblastoma multiforme.

    05:02 You have a greater nuclear pleomorphism. I would highly recommend that you know in great detail the microscopic feature of glioblastoma. Increased mitotic figure, what's necrosis and vascular. And we have perhaps endothelial cell proliferation representing your angiogenesis, glioblastoma multiforme.

    About the Lecture

    The lecture Neuroepithelial Tumors: Astrocytoma by Carlo Raj, MD is from the course Tumors of the CNS.

    Included Quiz Questions

    1. Inactivation of the p53 gene
    2. Inactivation of the p21 gene
    3. Inactivation of the PDGF-A gene
    4. Inactivation of the EGFR gene
    5. Activation of the BCR/ABL gene
    1. Necrosis and endothelial cell proliferation
    2. Perivascular rosettes and rod-shaped blepharoplasts
    3. Spindle cells concentrically arranged in a whorled pattern
    4. Cystic spaces, calcifications, and "wet" keratin
    5. Low mitotic rate

    Author of lecture Neuroepithelial Tumors: Astrocytoma

     Carlo Raj, MD

    Carlo Raj, MD

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