Colon dysplasia | Gastrointestinal system diseases | Health & Medicine | Khan Academy

SAL: This is Sal, and I’m
still at Stanford Medical School with Dr. Connolly. DOCTOR CONNOLLY: Sal, we’re
going to continue going. You going to get one
unit of credit for today. SAL: Excellent. My mother would be proud. DOCTOR CONNOLLY: So what
we’re going to look at today is a colon polyp. We had said before
polyp is something that’s going to
stick up like this. SAL: So in that last video
we saw, it was not a polyp. That was like an irritated
part of the bowel? DOCTOR CONNOLLY: Yeah. It was very low lying. It was– SAL: Let me get
you the pen here. We’ve got it all tangled up. DOCTOR CONNOLLY: It
was really just kind of a patch of
irritant right there. SAL: I see. DOCTOR CONNOLLY: So we’ve
got a bigger piece now. SAL: I see. That’s why it just looks–
everything is more– DOCTOR CONNOLLY: So you can see
the glands look tiny in here. SAL: So roughly that last slide,
how big would it be on this? DOCTOR CONNOLLY: It would
be about a piece like that. To be fair, it
probably was what was underlying this area right here. SAL: I see. DOCTOR CONNOLLY:
And then it grew on to be something more than that. SAL: It wasn’t this exact one. DOCTOR CONNOLLY: No, it wasn’t. SAL: It could grow on to be
something like this polyp. DOCTOR CONNOLLY: It
could grow into this. So this is something where
when we have a colon resection, if there’s a cancer,
often there’s a polyp. SAL: Right. DOCTOR CONNOLLY: There’s
an area of that patch like we saw with hyperplasia. SAL: Not necessarily
where the cancer is? It’s in that same
section of colon. DOCTOR CONNOLLY: Yeah. We find that people, if
they have colon cancer, often they have lots of
other pre-cancer lesions. And you can see– SAL: I see. Their bowels are just going
through a lot of trauma. DOCTOR CONNOLLY: Some of
it’s familial susceptibility, but a lot of it is that they are
showing a propensity to this. I don’t know if it’s from
environmental exposures or what. SAL: I see. And just to remind myself
on what we’re doing here, so you cut out a
bit of colon– you can kind of view it as
a tube– because there was some cancer there. DOCTOR CONNOLLY: Right. SAL: And then this thing might
be some other polyp that’s sitting in that same
section you cut out. DOCTOR CONNOLLY: Yeah. SAL: And maybe that
second slide we saw with the irritation, that
could be like right there. I see. DOCTOR CONNOLLY:
As matter of fact, it’s important that you
normally wouldn’t see this slide in a patient, because almost
all polyps, the colonoscopist is coming in. And they remove it
through the colonoscope. SAL: I see, because they don’t
know whether it’s cancerous or not. DOCTOR CONNOLLY:
They’ll remove it, but you wouldn’t
see the full wall. So right out here–
I mean, that’s all the way through
the wall and which you’ve got muscle up here. SAL: I see DOCTOR CONNOLLY: That’s the
muscular part of the wall. And so this is, really,
kind of going down to a full piece of the wall. SAL: I see. Wow. DOCTOR CONNOLLY: So
this is a larger piece, and this is in order
to show the polyp in its natural environment. So what we’re going
to do is we’re going to begin looking
at the polyp here. And so we’ll first
start way out here, which is to go back again
to the normal architecture. SAL: Right. DOCTOR CONNOLLY: So we had said
there are supposed to be tubes. Luckily, this one,
it’s cut right down the middle of the tube. So you can see how big the
hole is supposed to be. And so this is normal
architecture there. And then if I just
go out a little bit and I’m just going
to come along, you can see that you
have an area here in which there was
a bit of irritation. So it’s thrown up a little
bit like we saw before, but the real trouble is
this thing sticking out. SAL: Right. DOCTOR CONNOLLY:
And we wonder what is that thing sticking out. And so for the
medical students, we try to tell them to think like
the way the pathologist would be, that you first need to look
at the overall architecture. This is an abnormal
architecture. SAL: Yes. DOCTOR CONNOLLY:
You don’t usually have bumps sticking out. Then the next thing
you’re going to do– SAL: In 3D it would
look like a mushroom? DOCTOR CONNOLLY: Yeah. So it would look
like a mushroom. Actually, they tend to have
foldings on the top of them, so a little more like
cauliflower, because they tend to be cauliflower colored. SAL: I see. DOCTOR CONNOLLY: So then
when you look here– SAL: That color, too? DOCTOR CONNOLLY: Yeah. They don’t have
much color to them. In fact, the colonoscopist,
when they look at a polyp, can kind of tell if
there’s a chance of cancer, because they begin having
weird blood vessel samples. SAL: And just to be clear,
they’re not this purplish color that we’re seeing on this slide. DOCTOR CONNOLLY: No. SAL: This is color added. DOCTOR CONNOLLY:
Thin section and we had to put the– it would
be colorless otherwise, so we had to put a stain on it. SAL: Right, right. Makes sense. DOCTOR CONNOLLY: So now
what I’m going to do is I’m going to
draw the area where I’m going to do a comparison. See this thingamabob here? SAL: Yeah. DOCTOR CONNOLLY:
You’re going too– SAL: Look at that. DOCTOR CONNOLLY: So now– SAL: Miracles of science. DOCTOR CONNOLLY: Yeah. SAL: Technology. DOCTOR CONNOLLY:
So these are cells which are relatively normal. These are cells
which are abnormal. And when we look them, a
pathologist immediately says these look angry. SAL: They do. I would say that, too. DOCTOR CONNOLLY: And
so when you look– so what’s angry about
them is, first of all, they’re not committed
to behaving. Proper behavior over here. Nuclei belong at the bottom. Things that you’re supposed
to do for your job, J-O-B, are at the top. SAL: Yes. DOCTOR CONNOLLY: And so
when you look at these guys, it’s like, where’s your job? And so a few of them
are making mucin, but these ones have nuclei of
different sizes and shapes. SAL: Yeah. And they’re all just– DOCTOR CONNOLLY: They’re
just doing their own thing. SAL: They’re not
even doing mucin. DOCTOR CONNOLLY:
No, some make mucin, but a lot of them all
they’re doing is growing. And so usually there’s
a playoff between that if you’re committed
to your specific job– and we call it differentiation. SAL: Right, right. DOCTOR CONNOLLY: So
if you’re committed to your differentiation,
you tend not to have as much
propensity to grow. And if you tend
to grow a lot, you tend not to do the
differentiation. And so this is
largely that you have this sort of chaos
of nuclei, less commitment to the
normal structures. And you’re not
producing as much. And so what this, this
is now called dysplasia. SAL: Dysplasia. DOCTOR CONNOLLY: D-Y-S. SAL: Right, plasia
in the wrong thing. DOCTOR CONNOLLY: So
it’s the wrong growth. And so that’s what
we’re saying is we don’t like the
looks of these ones, and so these individual cells
look dysplastic and they grow. So then to tell
whether it’s cancer, cancer means in this
organ that you’ve grown across this
line in the sand. SAL: So let me– so
literally if you’ve crossed this boundary
right over here, cancer? DOCTOR CONNOLLY: Right. SAL: So even if I’m
in the polyp up here and I’m controlling
uncontrollably cancer cells and it’s mutated and
it’s not killing itself the way it’s supposed
to, you still would not call it
officially cancer? DOCTOR CONNOLLY: No. So what happens is that there’s
a middle term where it’s a cancer still in
the usual place, and that’s carcinoma in situ. SAL: I see. DOCTOR CONNOLLY: So
carcinoma in situ means it’s not an
invasive cancer. And therefore, most people would
not really call it a cancer. It’s just so wild
looking up here, you know that it
would do that if it was given any chance or time. SAL: I see. So what we’re saying
is if something was out here, carcinoma
in situ, that eventually it probably would make its way. DOCTOR CONNOLLY: Yeah. It just looks so
committed to growth and so aggressive and so
little differentiation that you know if
you gave it time, you’d worry that it would grow. SAL: Makes sense. DOCTOR CONNOLLY: So
with here though, this is dysplasia, where
it’s very upsetting that it’s growing so fast. But what’s important about this
is in hyperplasia, if you took away the stimulus or irritant,
it would go back to normal. This will not. SAL: I see. Like we said, if
there’s some irritant unless we do–
like a week later, we had a couple weeks later
that hyperplasia would go away. Dysplasia is here to stay. DOCTOR CONNOLLY: That’s right. And so the key word
we use is autonomous. SAL: Autonomous. It’s independent. DOCTOR CONNOLLY:
It’s just whatever. So it will grow no matter what. It doesn’t care about clues
from neighboring cells. It doesn’t need
something driving it. So what you have then
is this is growing. And if it’s growing and it’s
all by itself and growing, it’s then called a neoplasia. So that’s our last plasia. SAL: So neoplasia
showing dysplasia– DOCTOR CONNOLLY: Yep. So dysplasia just is
more of when you go in to look at these
guys, these features– SAL: Oh. It’s like a particular feature. DOCTOR CONNOLLY: These
cells aren’t growing right. SAL: So that’s an
example of dysplasia. DOCTOR CONNOLLY: Right. That’s dysplasia. And then overall, this
lump is a new growth. SAL: New growth, neo. DOCTOR CONNOLLY:
It’s a new plasia, and we you reserve it in the
medical field for meaning it’s growing on its own. SAL: And how do
we know it’s new? Because as you said, it sticks
around like the hyperplasia. So how do we know this
wasn’t around for a year? DOCTOR CONNOLLY:
Oh, it probably was. So I think it actually
came from an area here. And the thinking would
be that you probably had irritants or hyperplasia. It would continue to grow. Cells divide. Cells divide too much, and then
one of them made a mistake. And so then it clicked on
something where it would say, you know what, from now on I’m
not listening to any clues. SAL: And then all of its
descendants were crazy, too. DOCTOR CONNOLLY: That’s right. So then it would then
have a real mean streak, and so then they
would grow from here. So this is an area
where you can see– SAL: I see that pattern
in my own family. DOCTOR CONNOLLY: Yeah, exactly. So then here, these
are more normal glands. But even these,
that’s dysplasia. So these are growing,
and they do not have a good pattern of growth. And overall, this
lump is a neoplasia. SAL: I see. So when we say new, it’s kind
of newer than the other tissue. DOCTOR CONNOLLY: Yeah. We don’t really
mean so much the new for– meaning that’s new
as much as its own thing. New kid on the block. SAL: OK. DOCTOR CONNOLLY: So
this is the neoplasia. So this one here is a polyp. It has features of
dysplasia, but we would say we see no cancer. SAL: How would you know that? DOCTOR CONNOLLY: And so– SAL: Right, because it never
crossed a boundary line. DOCTOR CONNOLLY:
And there’s a reason why the boundary is important,
is that if you look here, these are all the surface cells. Down here, these
are the vessels that go to the rest of the body. These are blood vessels. These ones are
called lymphatics, and what lymphatics
are is they just take the clear
fluid around there. SAL: So these right here are
the lymphatics, the clear fluid. Fluid can go back and
forth between blood vessels and the lymph system? DOCTOR CONNOLLY: Yeah. Usually what happens
is that blood comes in an artery like this, goes on
down to these little vessels. And then a little bit
of the clear parts of it will kind of leak out into it. SAL: The red blood cells are
too big, kind of leak out. DOCTOR CONNOLLY: Yeah. So then the lymph is the
clear stuff that comes out. And then this is
how it gets back to the rest of your body are
through these lymphatics, so you can see you do not
want neoplastic cells in the– SAL: Right, because
once they’re in there, they can get to any
part of the body. DOCTOR CONNOLLY: Go anyplace. And then guess what. Set up shop. New kids on the block. They just do what they want. SAL: Mis-mis-stas. I can’t say the word. DOCTOR CONNOLLY: Metastasis. So metastasis would be if
it gets into these things, it can get out of
the colon in a hurry. SAL: Go anywhere
in the body, right. DOCTOR CONNOLLY: So this is
one where it is not cancer, and it has not
invaded these areas where it gets the
rest of the body. SAL: Fascinating.


  1. This is awesome! 😀

    Sal, can you ask if it's significant that the polyp looks like it's about to come off? Also, there were red-looking cells(?) in the polyp – what are those?

  2. I am not a med student, and this may sound stupid 🙁 but after watching this video and the two previous ones, I am wondering what the difference is between neoplasia, carcinoma in situ, and tumor?

  3. @Lemonbebe
    Neoplasia is a general term for increased proliferation of cells in a given area,tumor is roughly synonimous with neoplasia (although it indicates a swelling).Carcinoma in situ is a non-tumorous neoplasia,whereby cells proliferate in one given area without swelling.Sometimes carcinoma in situ is defined as the stage before cancer.

  4. It's interesting how there's a blood vessel in close proxymity to the polyp. It being there is making the polyp more possible by providing nutrition to the growth.

  5. @SuperLLL So basically neoplasia is a very broad term for any rapidly dividing cells, including tumor? And carcinoma in situ has a potential to become malignant? (Likewise, I am not a med student so please understand any ignorance I made…)

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