0:00

How about appendamoma?

0:02

So this is an interesting tumor too.

0:04

So most of you are familiar that usually sup tentorial,

0:08

appendamoma are intraparenchymal.

0:12

The fourth ventricular

0:13

or posterior fossa ones are inside the ventricle

0:16

and the cord one is in the intramedullary.

0:20

I often wondered why we don't often see

0:23

appendamoma right in the, in the middle of third

0:27

or fourth, um, lateral ventricle.

0:29

Most of the appendamoma super temporally that I've seen,

0:33

they're all in the sial, uh, parenchymal compartment.

0:38

But then now all these, uh,

0:41

genetic information is coming out.

0:43

So 2016

0:44

and 2021 WHO now are classifying super tentorial

0:49

ependymomas, particularly in pediatric age group based on

0:53

this very sophisticated molecular markers.

0:56

So the really fusion positive

0:59

super tentorial append omas are one

1:02

of the most aggressive append omas

1:04

or commonly occurring in pediatric age group.

1:08

And they look even worse than some

1:10

of the more really aggressive glioblastomas.

1:13

And most of these appendamoma,

1:16

particularly the relay fusion ones that I've seen, they tend

1:20

to be intra parran.

1:22

But then when they do recur,

1:24

they can recur all along the dural surface.

1:28

So their biology is very different than the typical

1:31

appendamoma that I've seen.

1:34

So there are two subtypes that the WHO has, uh,

1:38

clearly defined in the 2021 are the relay

1:42

fusion and yap.

1:43

One, I have yet to see a yap one molecular

1:46

altered, uh, appendamoma.

1:48

But like I said before,

1:50

the super tentorial appendant in a young child,

1:54

they tend to be this very aggressive, um,

1:58

molecular variant called relay fusion is the most

2:01

common one that I've seen.

2:02

And one thing that I wanna stress that relay appendamoma,

2:06

when they do recur, they can recur along the dura.

2:10

So please, if you're, if you know the molecular feature,

2:14

please look very closely at the dural margin

2:18

'cause it may be the first sign of recurrence.

2:20

How about intraventricular posterior fossa?

2:24

So now we know clearly intraparenchymal, sial,

2:29

appendamoma and posterior fossa intraventricular

2:33

addendums are genetically

2:36

molecularly completely different.

2:39

They may look similar on histopath pathology,

2:42

but they are not, uh, related at all in terms of

2:47

molecular genetics.

2:50

So what are the two subtypes that WHO defined in the 2021

2:55

and the two subtypes are posterior sate, Panama

2:58

Type A, posterior fossa, uh, appendamoma type B.

3:03

So what are the type A versus type B?

3:05

So the type A looks like this.

3:08

They almost look like a CP angle

3:12

or lower, uh,

3:13

medullary cistern tumor going out into the foramen.

3:17

Luka often, and this is called the PFA,

3:22

or I call it the PF appendamoma Asymmetric

3:26

'cause it's off to the one side.

3:28

And this is an awful prognostic appendamoma

3:32

and unfortunately much more common in pediatric age group.

3:37

And then there's this subtype, the group B are the ones

3:41

that sits usually in the midline, kind

3:44

of simulate the appearance of a medulloblastoma group three

3:48

because they are midline enhances.

3:52

But remember, append omas are not reduced on diffusion.

3:56

And this is what I call the posterior sate pendulum.

4:00

That looks like a ball.

4:02

But here you could see

4:03

that they are actually very different.

4:05

One is in the midline, one is asymmetric,

4:08

and it also turns out

4:09

that they're very different genetically.

4:11

So PFAI call it a stand for asymmetric

4:16

group B, B stand for ball.

4:18

So let's look at the tumor types a little diff

4:21

um, more carefully.

4:22

So here's group a appendamoma type A asymmetric off

4:27

midline, and they tend to have more necrosis hemorrhage.

4:32

And these are much more aggressive component

4:35

and they have a unique genetic and molecular marker.

4:39

Very different from P-F-A-A-P-F-B, excuse me.

4:43

And this is much more common in pediatric age group.

4:47

Here's the PFB group, more like ball shaped

4:51

in the midline and not as much as necrosis.

4:55

Little less hemorrhage. The midline location.

4:58

And this is the type of append omas that tend

5:01

to occur older children or adult patients.

5:04

And their main presenting symptoms they tend

5:06

to present earlier because of the obstructive hydrocephalus

5:11

and they're very rarely invasive

5:14

or infiltrative at all compared to the PFA variant.

5:19

So here's PFA, the awful, um,

5:23

much more prognostically worrisome type of append toomas.

5:27

And this unfortunately is much more common in

5:30

pediatric age group.

5:32

And they have a very specific molecular markers

5:36

that are very different than PFB, the one

5:39

that looks like a ball shaped in the midline

5:41

posterior fossa.

5:43

This is a ball shape, it's a better prognosis

5:46

and affects adults a little bit more than pediatric age

5:50

group.