Neuroepithelial Tumors: Medulloblastoma

by Carlo Raj, MD

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    00:01 Here, we’ll take a look at a neuroepithelial tumor.

    00:03 This is called medulloblastoma.

    00:06 Right off the bat, let me tell you, medulloblastoma will be the most common brain primary tumor or primary CNS tumor in a child.

    00:16 Now, with that said, let’s take a look at what it’s referring to.

    00:21 Sometimes, you see the abbreviation when you’re reading a journal or whatever, BMJ, Lancet, NEJM, what have you.

    00:31 And you might see the abbreviation pNET.

    00:33 In fact, you have or you will.

    00:36 It stands for primitive neuroectodermal tumor, pNET.

    00:41 You see it? Here, you want to think of this as being embryonal neoplasm.

    00:46 Embroyonal.

    00:47 I just began this discussion by calling this a primary CNS tumor in a child.

    00:54 The median age, seven.

    00:57 70% present in patients under age 20, and they make up 10% of all brain tumors in patients under the age of 19.

    01:05 Located where? Yet another one, right in that area in the vicinity of the fourth ventricle and the cerebellum.

    01:14 Right in that vicinity.

    01:15 So give me three right now in a child that will be in that region, three.

    01:21 Most common astrocytoma in a child, pilocytic.

    01:24 What about an ependymoma? It could be located in the floor of the fourth ventricle.

    01:28 And here we have a medulloblastoma.

    01:30 Where is it located? The midline of the cerebellum.

    01:33 All of these could cause what? Obstructive non-communicating type of hydrocephalus.

    01:37 Clear? So as you can see here, there’s a decent, decent list of differentials causing non-communicating.

    01:46 Rapid growth, rapid growth.

    01:48 May occlude flow of outflow of CSF resulting in hydrocephalus as we mentioned.

    01:53 Now, these small blue cells -- so if you want from now on, medulloblastoma.

    01:58 B, blastoma.

    01:59 Small blue cells is the histologic description, may then go into the CSF.

    02:08 Keep that in mind.

    02:10 If you take a look at this imaging study, you’ll notice where are we? You see that structure where we have the cerebellum.

    02:17 And you find that increased opacity, which then represents a tumor.

    02:23 It looks like it’s in the midline of this child’s image of the brain and therefore, you can notice that now as it moves anteriorly, that it’s then going to cause obstruction of the outflow of your CSF from the fourth ventricle most likely.

    02:40 This is medulloblastoma.

    02:45 A couple of things that I wish to bring to your attention under medulloblastoma.

    02:48 You want to know this in greater detail because it is a common, common, primary CNS tumor in a child.

    02:54 Well-circumscribed, gray and friable.

    02:58 Microscopically, sheets of anaplastic cells.

    03:01 Take a look at these small cells with little cytoplasm and hyperchromatic nuclei that are elongated or crescent shaped.

    03:11 And by hyperchromatic nuclei, we are referring to this as being – Take a look at these sheets of small blue cells.

    03:19 Medullablastoma.

    03:23 Clinical presentation is important.

    03:25 Increased intracranial pressure as you can imagine.

    03:27 Ataxia because we’re referring to the cerebellum being affected.

    03:31 Clinical features, we have highly malignant tumor, highly malignant.

    03:35 Unfortunately, may disseminate into the CSF, a common complication because of its increased aggressiveness.

    03:43 We call this drop metastasis.

    03:45 Mets stands for metastasis.

    03:48 Poor prognosis, unfortunately, in a child.

    03:51 And that just makes me sad and it’s radiosensitive, but poor prognosis.

    03:57 Please make sure that you know medulloblastoma in greater detail.

    About the Lecture

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

    Included Quiz Questions

    1. Medulloblastoma
    2. Oligodendroglioma
    3. Pilocytic astrocytoma
    4. Ependymoma
    5. Pleomorphic xanthoastrocytoma
    1. 7 years
    2. 17 years
    3. 8 years
    4. 6 years
    5. Lymphoma
    1. Disseminates into the CSF via drop metastasis.
    2. Causes a decrease in intracranial pressure.
    3. Has a good prognosis.
    4. Is not radiosensitive .
    5. Causes a communicating type of hydrocephalus.

    Author of lecture Neuroepithelial Tumors: Medulloblastoma

     Carlo Raj, MD

    Carlo Raj, MD

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