This is an adenoma, and just to review the main features, first of all, it has some brown color compared to the surrounding mucosa, and you want to try to feel confident that the brown color is the result of blood vessels, as opposed to just inflammation, because redness in a polyp, like an inflammatory polyp, will also appear brown when you look at it in NBI. The other thing is that the pits are somewhat variable in shape. You can see pits that are tubular, oval in shape, and so this is a typical adenoma. Here's another one. The vessels in an adenoma are also characteristically thicker. So the brown lines here tend to be thicker than the vessels that we'll see in hyperplastic polyps. You can see that the pits are variable in shape. That's a key component of high-confidence adenomas. Overall, I think that about 80% of colorectal polyps are high-confidence, either adenomas or hyperplastic polyps, and this is another one, at least on the top part of it, quite brown vessels, variable-shaped, white structures. Those are presumably the pits. Here's just an extremely high-confidence adenoma. Now we see pits that are quite long and tubular. Some of them are branching, sort of like KUDO4. I will say, in general, that NICE2 kind of correlates well with KUDO3 and 4. NICE1 correlates with KUDO1 and 2. The KUDO classification really was developed for dichromoendoscopy in combination with high-magnification scopes, and the NICE classification was developed for just high-definition scopes, so they don't necessarily correlate perfectly, but in clinical practice, a lot of people sort of use them interchangeably and apply the KUDO classification when you're just using high-definition scopes, so this would probably be KUDO3L and 4. NICE2, extremely high-confidence adenoma. And here is another just classic one, lots of brown. The brown is all from vessels, these thick vessels. The pits are quite variable in shape. This one is just overwhelmingly classic, KUDO3L and 4. NICE2, lots of brown. All the brown is from vessels. You look down in the lower right, you can see how thick the vessels can be in adenomas. Here's a very small lesion. So this lesion is also an adenoma. It's got brown. You can see that the pits are tubular on it, and the vessels are surrounding these pits. Now this lesion, I would say, is probably about three millimeters in size, somewhere between two and three millimeters. If you can imagine the tip of the snare sheath approaching this lesion, the tip of the snare sheath is 2.4 millimeters in diameter, so it's a good way to judge if you push it right up against one of these polyps. Now we find, and I'll come back to this, that about 15% of the adenomas that we see endoscopically and verify by the NICE classification are reported by our pathologists as normal. And that is primarily because we send the polyp as a much larger piece of tissue. When we cold snare, often we have a piece of tissue that is five to 10 times or more bigger than the actual size of the polyp. The pathologists don't see the polyp grossly when they cut it. So we actually, in clinical practice, if we have good photography of polyps, we will still call them adenomas, treat them like adenomas, even if they're not verified as such. So one use that I put this to right now in practice is, like say I have six lesions that all look to be high-confidence adenomas, and only four of them are verified by the pathologist, I would still treat the patient from a surveillance standpoint, like they had six adenomas. They would come back in three years as opposed to five years. We can now, according to our guidelines, bring people back with three or four adenomas in three to five years. And if they're all diminutive, I usually choose five years. But if I know there's six, I probably will still choose three years. So my point is that I don't necessarily rely on what the pathologists say when we're dealing with definite diminutive adenomas. I think another factor that contributes to this is fragmentation. The specimens can fragment and on the way back into the trap. So that's another use. Here's another tiny adenoma. Has a little bit of a brown spot in it that I would call the valley sign. And I'll come back to that in a minute. So again, we're looking primarily at type 2 lesions. These are adenomas. I usually refer to them as conventional adenomas. Here is another one, brown color, tubular white structures. These are both adenomas. And the one on the right I like because you can see how thick those brown lines are. This is something that you want to get used to looking at is asking yourself how thick the vessels are. The same thing is true really over on the left. You've got some vessels there that are just really thick. You won't see vessels that thick in general on type 1 lesions. It's just something that you don't see. If you look at the left lesion, you can also see this brown furrow that runs across it. There's two of them. One sort of on the right side and one running across the left side. That is the valley sign. And the valley sign is very specific for adenomas. If you look at that close up, you'll see that there are a lot of very small vessels in there that give it its brown color. And that's not really a depression. I would not even call that a pseudodepression. And so it's been named the valley sign. And it's not that sensitive for adenomas. It's seen in about 40% to 50% of adenomas, but it's highly specific for adenomas. It's something that's kind of like NICE 3. Not much sensitivity, but very high specificity. Now this is a lesion that I show you that if you initially, if you ask yourself, what is this, you probably would say this is an adenoma. But it's an example of the criteria don't work perfectly. And this is a hyperplastic polyp. And a couple of hints are the vessels are not very thick. Sometimes you see the vessels, there's actually a tiny vessel and a hyperplastic polyp basically surrounding every pit. The other thing I think is in the central portion of it, a lot of the pits are relatively uniform in size. But I just point this out to say that there isn't any system that's foolproof. And this is an example of where there might be a hint, but you could easily make a mistake. I will say that in general, the variability in pit size is something to pay attention to. If you have what you think are prominent vessels and brown color, but you don't see hardly any variation in pit size, I tend to call it, make that a low confidence adenoma most of the time. Yeah, a low confidence lesion.

adenomas

colorectal polyps

NICE classification

KUDO classification

valley sign