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S: This is Sal here at Stanford Medical School with Dr. Andy Connely, a pathologist,

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this is the 2nd video in our series looking at these slides.

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Dr: We left off last time looking at this piece here, normal colon,

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we had said this is an example of something you'd see at the edge of a specimen for colon cancer.

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Now I'm going to the next one which is a slightly more worrisome area if

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you're a pathologist looking through the colon. I'm going to zoom in just a little bit

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S: That's very worrisome, compared to the last one.

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Dr: What we don't like about it, we saw before this is what a normal gland looks like,

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It's a test-tube shape, going down, and it has these cells which are normal.

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Now, all of a sudden it is a little thicker here, and what catches our eye is these are

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not straight test-tubes anymore, they divide, go in and out like that.

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S: They still are test-tubes, they just look like circles because of the cross-section?

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Dr: That's right, but when you come from the surface here and go down--

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they normally should never branch.

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So these ones are branching, and that's always bad, and in a cross-section

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there's normally a little hole in the middle, where the mucin...

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you can see it spilling out, coming right out.

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This one here looks different, it's piled up, it's bigger around, cells are piled up,

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and they branch.

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So we look a little more closely at this, and we say,

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"Hmm, I wonder if that's cancer? Could it be pre-cancer? Or just an area of irritation?"

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A common response of the body to irritation is to change.

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And like we said before, the epithelium is the top layer, facing the outside world.

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If it's irritated, it will change, and in this case it's changing by undergoing more growth.

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S: Even if it's not cancer, is there a higher chance of it becoming cancer in the future?

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Dr: A lot of cancers that appear in the body come from parts of the body that are

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either irritated or have some sort of environmental challenges that are constantly at them,

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and part of that is because there is a lot of cell division, if you keep dividing a cell,

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you might have errors in DNA.

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S: I see, so that's why skin cells, bowel cells...

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Dr: That's right, and even things like liver, if you keep damaging your liver,

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you might have higher chance for liver cancer.

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So when a pathologist looks at this area and says,

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"Well, it's a dividing gland...

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It's kind of thrown up in these areas..."

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But largely they're still making mucin, or they're this type here, which looks like it's tall

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and probably absorbing water.

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S: So even in these test-tube-like vessels, there are these absorptive cells as well?

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Dr: Right. So here, we would sign this off as 'hyperplasia'.

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S: Hyperplasia. Hyper-, too much of something. And -plasia?

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Dr: Growth. Plasia just means growth. So hyperplasia means too much growth.

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But the important thing, if you took away the irritant, it wouldn't do this.

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So if you took away whatever the irritant is, for the hyperplasia,

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it would go back to being normal.

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S: So there was some stimulus that was causing these cells to do this--some chemical, etc.

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Dr: Right. We're rarely sure because so many things just float on through.

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It's really hard to know. But this is probably too much growth due to some irritant.

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S: Is it possible that it was just when this section of the colon was taken out,

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if this was done a day later, [hyperplasia] might not have been there?

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Dr: Probably take longer that, a couple of weeks.

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Because what happens is the cells come from the bottom, and they work their way to the top,

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and eventually the top...

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S: So it works sort of like the skin, these cells are being constantly used up

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because things keep scraping by them.

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Dr: They do. There is a lot known now about stem cells, the stem cells for the intestines are these guys.

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S: How do you differentiate those from the others?

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Dr: At the very bottom, the bottom hemisphere, there are going to be cells that do not have

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the open chromatin, and kinda elongated. There maybe ones that are endocrine cells,

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meaning they release hormones. And so they may have hormone releasing cells,

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but in this bottom hemisphere, turns out to be where the intestine keeps [stem cells].

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S: Stem cells are cells that haven't picked their jobs yet?

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Dr: They haven't. There are all kinds of stem cells: the stem cells that can make a whole body/being,

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there is also the kind that can make the rest of the colon.

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So, this probably one that can make the rest of the epithelium,

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with these two different cell types. So they're down here at the bottom, where you'd want them.

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So this is a hyperplasia. I'd like to show you next, the next step which is a pre-cancer region.

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S: NEXT VIDEO!! =D