Welcome to ASG Endo Hangouts for GI Fellows. These webinars feature expert physicians in their field, and I'm very excited for today's presentation. The American Society for Gastrointestinal Endoscopy appreciates your participation in tonight's event, Optical Diagnosis of Colon Polyps and Magnifying Endoscopy. My name is Marilyn Amador, and I will be the facilitator for this presentation. Before we get started, just a few housekeeping items. We want to make the session interactive, so feel free to ask questions at any time by clicking the Q&A feature on the bottom of your screen. Once you click on the feature, you can type in your question and hit Return to submit the message. Please note that this presentation is being recorded and will be posted within two business days on GILeap. You will have ongoing access to the recording in GILeap as part of your registration. Now it is my pleasure to hand over the presentation to our GI Fellow Moderator, Dr. Douglas Wodomura from Queen's University, Kingston, Ontario. Thank you very much, Marilyn. It's my pleasure to be here. As Marilyn said, my name is Douglas. I'm happy to have worked with all of our panelists today and our moderator. I was a GI Fellow at Queen's, and then I did my Advanced Endoscopy Fellowship with Dr. Shahidi and UBC. I'll start by introducing the great team we have today. Dr. Beshara is currently a Staff Gastroenterologist at Queen's University. He did his GI Fellowship at Queen's University and subsequently an Advanced Endoscopy Fellowship at St. Michael's Hospital in Toronto. Following that, he was the first Canadian to complete the one-year fellowship at Shoah University, training under Dr. Haruhiro Inoue, the founder of POEM, and honing his third space skills with ESD and other advanced procedures and optical diagnosis, of course. He then brought these skills back to Kingston, Ontario, where his practice includes POEM, as well as hepatobiliary disease, still doing ERCPs, amongst many other things. It was a pleasure to learn under Rob. Our second panelist here is Dr. Eric Lam, who is a Staff Gastroenterologist at St. Paul's Hospital in Vancouver, BC, Canada. Dr. Lam also has a hepatobiliary practice and a very interesting training course. After finishing his gastroenterology fellowship at the University of Alberta in Canada, he subsequently did a transplant hepatology fellowship and then decided to do more training with hepatobiliary things with the U.S. at the University of Montreal, and then here and there further training, a bit of third space training in Japan as well, and a great resource. His current practice includes hepatobiliary. I was honoured to learn EUS and ERCP from him, as well as a good amount of third space ESDs, POEMs, and luminal endoscopy as well, so just an all-around practice. And finally, Dr. Shahidi is, again, a Staff Gastroenterologist at St. Paul's Hospital at Vancouver, BC. After finishing his fellowship at the University of British Columbia, he then did a two-year fellowship at the University of Sydney, training under the esteemed Dr. Michael Bourke, with focus, of course, on tissue resection, EMRs, of course, but also third space endoscopy, ESDs, POEMs as well. Brought those skills back to Vancouver and is currently a clinician researcher with a strong focus on luminal endoscopy, and it was also a pleasure to be involved with your cases, Neil, and to mess up your polyps when I had the chance. So, yeah, I'm honoured to be here amongst the greats, and I hope we will have a great session. And so the focus of today's talk is Endoscopic Examination of Clonic Polyps Optical Evaluation. I'm just going to grab control of the presentation here. Excellent. And so these are some disclosures from some of our presenters. And we'll go over the objectives very quickly. Basically, the main objective of the talk is to appreciate the gross and the microscopic exam of some of these clonic polyps, and we're going to be going through a lot of different cases, a lot of pictures, a lot of videos, and I think it's going to be a worthwhile experience. We're going to look for high-risk features of these clonic polyps, and we're going to go over some of the criteria classifications that you might already know, but specifically the NICE and the JNET, and we'll talk a little bit about KUDO as well. And so I do have a...we're going to use a lot of polls here and a lot of, yeah, polls everywhere for interactivity. I'm just going to see if I can put something into the chat for a link to the poll everywhere. So while you do that, Doug, I'll just...before I forget, I just want to mention to everyone, again, in terms of who's interested in optical diagnosis and polyp management, there's a project headed by Catherine Walsh that I've been kind of lucky enough to participate in. It's the Polyp Recognition Improvement Module for Endoscopists, and it's a cognitive simulation platform that we're developing, and it should be launching this fall through the ASGE. The fellows will have an opportunity to use it, and it really will help develop their lesion recognition and management decision skills for polyp and optical diagnosis, so look out for it this fall. The other thing I wanted to mention as well, just before we get started, is that so Douglas did his training, as he mentioned, with me and General GI in Kingston, then did therapeutics in Vancouver, and he's going to be going to do ESD and optical diagnosis with Dr. Toyonaga and Kobe, really one of the greats in endoscopic diagnosis and ESD in the world, and Doug will very soon be teaching us all, and I'm really looking forward to learning from him when he comes back to Canada, and I think everyone will hear about him soon. Very kind of you. Thanks, Rob. So I'm not able to send out the link in the chat, but once we get to the first slide, the link for the polls will be up first, so we'll just have to leave that one up for a little bit, but basically what we're going to do is we're going to run through a bunch of cases, going through the macroscopic assessment, talking about these classifications, and then looking at the microscopic assessment as well. Nice, and Janet, it'll be hopefully very interactive, feel free to ask questions throughout, and I'll try to get them to the moderators. So we're going to start with just some housekeeping stuff, some polls to get us warmed up, as well as to figure out the knowledge of the group here, and so we'll start with the Paris classification, and we're just going to set up a poll here. It's everywhere. So the link there is at the top, PollUV slash Pacific Sky 466, and the question is, how familiar are you with the Paris classification? Very, somewhat, minimally, or not at all, and it will be the same link throughout the presentation, so please sign in to that link now, and you can keep it open, and the questions should change as we go along as well. Wait till we get some answers here, so everyone can log in. Okay, great. Looks like we're getting some trickling in here. That's good. So it looks like there's a pretty reasonable spread between people who are pretty confident with it and those who have some experience, so there's a good spread, so that'll be good in terms of when we go into chatting about it. Excellent, yeah. So it seems like everyone's at least heard of it, so that's good. We're going to move on to the next one here. Now it's the LST, same answers, but the LST classification, lateral spreading tumor classification. This is something else we'll go over. So maybe a bit less known than the Paris. I think it'll be an interesting thing to go over on the slides. Good. Okay, good. That's really good. Okay, and Eric also put the link in the chat. I just saw it there, to everyone. So if you want to just click through that, it's easier than typing in the link on your computer or your phone. Okay. We'll go to the third poll here. Nice classification. How familiar are you with the nice classification, the narrowband imaging classification? I think I answered this earlier. All right, yeah, so some familiar with it. Yeah, opticals, optics already, so that's good. It's a real kind of diverse knowledge base, so that will be good to hopefully kind of bring everyone up to the similar level of kind of the classification, so that's great. I'm interested with this one. I think, so our last kind of warm-up poll here is about the JNET classification, another MBI classification. Same thing, very somewhat minimally or not at all. So maybe a little bit less familiarity with the JNET classification as compared to nice, which makes sense, I think. So that's good. We will be going over that. Okay, excellent. Rob, I'm going to move over to the videos, if that's all right here. Great. Okay, we'll start with a few intro cases just to kind of get warmed up here. So hopefully the videos are not too choppy. We're starting to look at a polyp here. I think this was in the descending colon, kind of a Paris 1S polyp, fairly small, probably a subcentimeter. You can see that this is Dr. Bechere's video, so he has an optical mode on, the BLI, blue light imaging, on the Fuji scopes, and he has a magnification scope as well, so he can really see the surface architecture, the vasculature, and the cryptepithelium. Okay, I think that's it there. And so we'll get to some still images in a second here. And just kind of off the top, the question will be, what histology do you think this is? And we have three categories there, and the poll will start here. So low-grade dysplasia, i.e. an adenoma, high-grade to SM1, we kind of combine those categories, or deeply invasive. And we will be coming back to these cases and kind of explaining why the answers and why they are what they are. So most people think it's a low-grade adenoma. Okay, so that's a good start. I think I'll move on from that one because it's a pretty majority there. Okay, second case, a bit of a different-appearing lesion here. And so we're in the rectum now. Dr. Becher was using a gastroscope there, so you can see this lesion is probably about two to three centimeters or so. Kind of a different morphology, probably a 1S with a depressed kind of center, so maybe a 2C lesion, and it looks a bit different. Again, using the optical modes on the Fujiscopes. And he'll be looking at it very carefully. I think you were telling me, Rob, that you actually used a cap for this, right? It's just you can't see it on the edges. Is that correct? Yeah, that's right. It's a soft, reprocessible black cap, so it's less traumatic for the tissue and made specifically for magnification. Right, and that helps you get kind of close and stabilized, right, when you're magnified. Yeah, that's right. Yeah, and you'll see a bit of that in a second, but you'll see how friable this thing is. And we will also explain, again, during the talk, in terms of the optical modes, so NBI, BLI, kind of what exactly they are and what they do, so we will go into that. This is just to kind of give you a bit of some things to think about as we're going through the cases and talk. Absolutely. Yeah, you can see it's pretty friable, right? So I'm probably just going to pause it there and get to the poll. Okay, same thing. What do you think the histology of this one is? I'll open up the poll right here. Okay. That's a pretty reasonable split. Pretty reasonable split, but definitely people think it's a bit more of an advanced lesion than the previous. Wow, nearly a 50-50 split there. That's interesting. Okay. And then there'll be one more case here. Another polyp in the rectum. This one has kind of that lateral spreading morphology, which we'll be talking about in a little bit, kind of a granular mixed morphology. Maybe a dominant module there. Again, using different optical modes to better look at things. It is an interesting lesion. Many, many areas to investigate carefully here. Dr. Becher is going to look closely at this middle center area. There we go. Yeah. Just kind of look at the, yeah, just looking at kind of the different appearances, as Doug mentioned, there's kind of a lot of different morphologies too. So just trying to kind of appreciate the differences between one area versus the other. Yeah. I can really see the surface architecture here. All right. So I'm going to pause it there. I think. Okay. I'm going to flip it to the next slide. Again, many, many different areas. Same thing. Good. All right. I'll flip it to the poll. What do we think this lesion is here? Okay. Very interesting. And again, people think it's more of an advanced, an advanced lesion as well. Okay. So that's great. So we will revisit these cases after Rob's section. So that'll be interesting. All right. So now we'll move on to the Paris classification. So this came out of a meeting, obviously in Paris in about 2002. And it was an international group of endoscopists, surgeons, gastroenterologists, oncologists, and is really a meeting to explore the applicability of the Japanese classification of superficial GI neoplasia, which has been around for a number of years prior to that. But this basically kind of brought it to the world stage. And that's kind of where the Paris classification came from amongst other things from this meeting. So the Paris classification is kind of one of the things that was introduced at that meeting. And it's basically just a gross way of describing polyps in terms of macroscopically. And they kind of had three very basic categories. And I think most people were familiar with this in the polls. So I won't spend too much time on it, but you had the protruding type, the flat type and excavated. And for colonic lesions, generally for excavated, you don't have any superficial neoplasia. If you have an excavated lesion in the colon, it's generally invasive by that time. So you really don't have excavated superficial GI neoplasia that's excavated in the colon. You may have that in the esophagus or the stomach. So in terms of the protruding, the two main types are the 1S and the 1P. And in terms of 1S is anything greater than 2.5 millimeters. You can estimate it based on a closed biopsy forcep. You can also have compound lesions here. So 1SP, so a pseudopedunculated lesion as well. Then the flat type, you have kind of three main subtypes. Your 2A, so slightly elevated. So anything 2.5 millimeters or less. So less than a biopsy forcep that's closed. A 2B, completely flat lesion. 2C, slightly depressed lesion, about 0.5 millimeters or less. So those are kind of the main types in terms of the Paris classification. And you can obviously have compound lesions. So a lesion that's a 2A plus 1S or a 2B plus 2A, 2A plus 2C. So you can have compound lesions and it kind of reflects the pathology that's quite heterogeneous. You can do your best to try to somewhat objectively describe it using the Paris classification. And it kind of lets you, you know, it describes what we already know. So for example, depressed lesions, so 2C lesions, even if they're small, so slightly depressed lesions, there's a significant chance of having submucosal carcinoma in them. So even lesions that are less than a centimeter, you can see about a 40% chance of submucosal cancer. It doesn't tell you the depth of the submucosal cancer, but it tells you the likelihood. And this was based from data from Japan of about 20,000 lesions. So depressed lesion, even small ones, significant chance of carcinoma. In terms of the protruding type, as lesions get larger, higher chance of submucosally invasive carcinoma. So again, just kind of trying to make somewhat objective what you know intuitively already. Then we'll move on to the LST classification, which I don't think as many people were familiar with. So you have four main categories. So you have your LST-G, so laterally spreading tumor, granular, homogenous, and they look like this. So again, nice, lumpy, bumpy, homogenous appearance. Then you have your granular mix. So they have a component that looks like this, but then there's at least one of these dominant nodules. And then you have your LST non-granular flat, so completely smooth surface without depression, and then smooth surface with a depression. It's called a pseudodepression, and it's just a nomenclature. It's an actual depression. So your LST-NG pseudodepressed. And from this, again, gross morphologic classification, there's a fair bit of information you can get. The risk of submucosal carcinoma is quite low in these granular homogenous lesions. Intermediate in the granular mix, about 15%. The non-granular flat, roughly 10%. The pseudodepressed, about 40%. And as the lesions get bigger, the risk also generally goes up. And not only the risk of submucosal carcinoma, but you can also get an estimate of procedural difficulty if you're going to remove it. So fibrosis tends to be quite low for the granular type. So even when they're large lesions, they tend to be removed fairly easily and quickly, and they lift very well. The granular mix, kind of low to intermediate risk of fibrosis. The non-granular flat, again, low to intermediate. The pseudodepressed generally don't lift very well, and they have a fair bit of fibrosis and can be quite challenging to remove. So the resection difficulty, it's not necessarily described in the literature, but it's based on my opinion and extrapolation. The other thing that you should know is the non-granular lesions tend to have a higher density of vasculature. So contrary to what you may think, these flat, smooth lesions, they tend to have a higher density of vessels in them as well. So something to take into consideration when you're removing them. So why is it important in terms of submucosal carcinoma? We keep talking about SM1 carcinoma or mucosal carcinoma. So in the GI tract, all the lesions or the neoplasia in the GI tract that's superficial, you can kind of break down in this way. So M1, M2, M3, et cetera. So this means carcinoma in the epithelium, M2 carcinoma that goes down to the lamina propria, M3 carcinoma that goes to the muscularis mucosa, then SM1, SM2, SM3. And that basically is in terms of the thirds of the submucosa. This cutoff here, 1000 micrometers, is different for all the different parts of the GI tract in terms of esophageal squamous, esophageal Barrett's carcinoma, gastric carcinoma, et cetera. So there's different numbers in terms of cutoffs of what's SM1, SM2, SM3. And this is why we care about the depth, because it can predict the risk of lymph node metastasis. And when you get to higher risk of lymph node metastasis, then you start thinking about formal oncologic resection with lymph node dissection. And traditionally, this is what has been taught and what's been in the literature. So for colonic lesions, things that are down to SM1 carcinoma, so just in the first third of the submucosa, have a very low risk of lymph node metastasis if they don't have any other high risk features, such as a lymphovascular invasion, tumor budding, poor differentiation. And then SM2 has an intermediate risk, and SM3 has a much higher risk. And generally, SM2, SM3 are managed surgically because of the lymph node metastasis risk. However, in recent years, more and more data has come out that even with deep submucosal invasion, if there are no other high risk features, the risk of lymph node metastasis is not as high as previously thought. So not much higher than SM1, which you can see here. And more recently, Evelyn Dekker's group performed a systematic review and meta-analysis. And kind of the bottom line that came out of it was that deep submucosal invasion, as a solitary risk factor for lymph node metastasis, is not that strong. And the absolute risk for deep submucosal invasion was about 2% to 3%, so not much higher than SM1. And perhaps that lesions that have deep submucosal invasion as the only risk factor potentially can be managed with local excision curatively. So I suspect in the coming years, the guidelines will likely change in terms of what can be deemed a curative resection in terms of local excision. So look out for that in the next couple of years in terms of things changing. So we'll move on to a practice lesion. This will be the first one. If you guys had to choose in terms of which one it would be, this is a lesion in the sigmoid colon. We think it's a LSTG homogenous, mixed type, LST-NG flat, or pseudodepressed. And this is with indigo carmine, and this is just with white light. And we're really just interested in the gross description in terms of the LST classification. So it looks like everyone already knows it's an LSTG mix, and I can stop talking. You guys already know what to do with these. That's good. So almost everyone picked LSTG mixed type, which is correct. There's at least one dominant nodule here. You can see the lateral margin has that granular homogenous appearance, and there's this big nodule, and there's another little nodule here at the back. And this ended up being a SM1 carcinoma that, because of the endoscopic findings, we decided to remove it with ESD. And thankfully, it was a curative resection. As I mentioned, it was SM1 without lymphovascular invasion and without any high-risk features. And this is the area of the superficial carcinoma here. So thankfully, it was a curative resection. So we'll move on to another lesion, and this is in the CECM. So if you had to choose between the four categories, which one would it be? That one's a little bit of a trickier lesion, a bit more subtle in terms of the findings in it. So I think we'll see a bit more, maybe see a bit more spread in this one as compared to the last one. So as expected, there's a bit more of a discrepancy between the subtypes. But overall, most people appear to think it's a LST-NG with pseudodepression, and you are correct. It's an LST-NG with pseudodepression. The pseudodepression is kind of just right in the center there. If you look just in this area on the left, hopefully you guys can see my cursor, yes? Yeah, we can see it. So this is the depressed area. And you can see it a bit here as well. Not so much in this image, but it was a pseudodepressed. So based on those features, we decided to remove it again via ESD, so we can remove it in one piece. And this is the area of carcinoma, a very subtle area. So this little boot that's basically going into the muscularis mucosa is the area of superficial carcinoma. And thankfully, no other high-risk features, and again, a curative resection. So saving them a potentially surgical resection. So in terms of some of the other high-risk gross morphologic features, so overall, so far, we just talked about gross morphology. So all this information you can get just from a gross examination without magnification, without looking very closely. So these other high-risk features that we'll briefly go over are fold convergence, which is here. So you see the folds coming together and fusing, a demarcated depressed area, which I'll show you, a stock or base swelling of the lesion, spontaneous bleeding, and chicken skin mucosa or white spots. So this is an example of fold convergence. So this was a lesion in the descending colon on the left. You can see one, two, at least three folds converging. And this was a massively, sub-mucosally massively invasive SM3, surgically resected without any lymph node metastasis and no other high-risk features. So potentially down the line, that might be something, depending on the guidelines, how they change, that could be curatively resected endoscopically. On the right is another lesion. This was in the sigmoid colon. You see three folds converging here, and it was also a depressed lesion. So this actually ended up being a T3 carcinoma with a positive lymph node and areas of poor differentiation. Here's another example of a demarcated depressed. These are two separate lesions, but you can see there's a slight depression, and within the depressed area, there's a clear demarcation inside it. So that's another high-risk feature. This lesion ended up being a, again, SM massive lesion with lymphovascular in the rectum. And this is that same lesion that I showed you on the last slide that ended up being a T3N1. You could see, again, a depression with a clear demarcation in that depressed area. So stalk or base swelling. So some of these lesions, this is kind of a pseudo-pedunculated lesion, but look at the kind of swollen or engorged stalk. So that's a risk factor for a more advanced lesion. This is from this publication here that describes stalk or base swelling. This is a lesion here seen on a patient that had a FIT testing and had this kind of swollen base of the small lesion, maybe about a centimeter or so. So it was removed via EMR in one piece and actually had SN3 adenocarcinoma in it, and they went to surgery. It didn't have any remaining carcinoma or lymph node metastasis, and it was moderately differentiated. And here is spontaneous bleeding, again, self-explanatory. This was a lesion in the rectum. Again, before I kind of even did anything, it was spontaneously bleeding, and you can see with the washing, again, it just kind of continues to ooze. So this was a mucinous adenocarcinoma with deep subucosal invasion and lymphovascular invasion, and it was removed surgically after kind of humming and hawing about it for quite some time during the examination. So chicken skin appearance. So that's basically these lipid-filled macrophages in the lamina propria, and you tend to see it in more advanced lesions. You can see here lipid-filled macrophages. And this is a lesion here in the rectum that we saw, and it ended up being a tubular adenoma with high-grade dysplasia and no carcinoma, and it ended up being that dominant nodule there. But you can see quite nicely here that chicken skin mucosa there at the periphery. So just some caution on gross morphology. There's a systematic review that included over 30,000 lesions and looked at using just gross morphology solely to predict subucosally-invasive carcinoma, and they compared it to optical diagnosis with NBI or magnification with chromoendoscopy. And they found that NBI and magnification was much more accurate, and the gross morphologic features was not as accurate as the image enhancement with NBI or magnification. So this basically tells you that if you see a lesion when you're doing your gross examination and it has some of these high-risk features, you really need to look at it very, very carefully with image-enhanced endoscopy and magnification if you have it available. So that's the discussion on gross morphology in terms of your macroscopic examination. So now we'll move on to microscopic assessment, and maybe I'll just pause for a minute and see if anyone has any questions or comments specifically about the macroscopic or gross morphologic examination of colonic lesions. I'm not sure, Doug, if there's anything in the chat yet or know about those. No, chat is pretty dead right now. Okay. All right. So we'll move on to the microscopic assessment. So briefly about PIT pattern, NICE classification, and JNET. So PIT pattern, I won't spend too much detail on it, but I really want everyone to kind of know what it is because it's often used and described somewhat inaccurately in day-to-day practice. But this is Dr. Kudo, who came up with the classification, and this is just columnar mucosa, and we'll say this is kind of normal columnar mucosa of the colon, and I just want to describe what PIT pattern is when you actually examine it, and we'll kind of put everything together in a few slides. But when you examine something for PIT pattern, you use indigo carmine or crystal violet generally. So indigo carmine isn't absorbed and doesn't stain. It actually just goes and pools in the PITs. So when you look at it with indigo carmine, the area that's blue ends up being the actual PIT, and that's what you're seeing, and that's what the PIT pattern is based on. If you use crystal violet, crystal violet stains the epithelium that's around the PIT and leaves the PIT essentially unstained. So that ends up being, you see the PIT as a lighter area, and this is what it looks like with crystal violet. So normal colonic mucosa, you see the tiny dot in the middle, that's the PIT that's unstained and stays pink, and then the epithelium, which is here, is stained with the crystal violet, and this is kind of what it looks like in a schematic form. So the PIT pattern classification, so you have about five main types, type 1 and type 2. Type 1 I just showed you in the last slide, and that's for normal mucosa. Type 2, there's a few subclassifications of it, but generally you have this kind of stellate shape, so a little bit bigger than the type 1, and also has a bit of a star shape, and that's generally seen with hyperplastic or serrated lesions. Type 3L and type 4 generally correspond to an adenoma, so type 3L generally corresponds to adenoma, type 4 corresponds generally to a tubulovilous adenoma. So you can see here with crystal violet, these long-appearing PITs, 3L, long, and type 4 generally almost looks like a brain, or kind of a gyrus-type appearance, and corresponds to a tubulovilous adenoma. 3S, so short or small, that generally corresponds to high-grade or superficial carcinoma, and you can see these tiny, tiny PITs here, so different from type 1 in that they're much smaller and denser. And 5I is irregular, and there's subclassifications in 5I as well that I won't go into, but you can see there, there are PITs, but there's no regular repeating appearance or pattern to them. And 5N is deeply invasive adenocarcinoma, so completely non-structural, so basically you don't really see any PITs at all. And the accuracy of this is probably the most accurate optical diagnosis classification we have in terms of predicting neoplastic versus non-neoplastic, about 98%, and superficial, or the presence of submucosal invasion based on the presence of the 5N, so massive submucosal invasion is quite accurate as well, about 95% accuracy. So now we're going to talk about what NBI is, and all the platforms now, whether it's Pentax, Fuji, Olympus, have similar technologies and similar lights that are used, and they all highlight the same thing. But the reason why I'm going to talk about NBI, because it was really the first one that was released that had this technology and highlighted what I'm about to show you. So they use the wavelengths 415 and 540, so basically a filter goes in front of the light source, filters everything out except the wavelengths 415 and 540, the reason they chose those is because those are most readily absorbed by hemoglobin, and as a result, most readily absorbed by the vessels of the GI tract, and highlight things much, much, much better. So 415 is a shorter wavelength, it's blue light, it basically gets absorbed by the superficial capillaries, and they end up appearing very dark, so very dark when you use that wavelength. The venules, which are a bit deeper, and the veins, which are deeper, don't get highlighted at all. And in terms of the reflection, the epithelium ends up reflecting the light, so it will appear white, which I'll show you in a minute. The other wavelength is 540, so a green light, higher energy, it goes a bit deeper, so you get some absorption by the venules, and they end up appearing very dark, whereas the capillaries, you don't get too much absorption, so they're a bit lighter in appearance, and you don't really get deep vein absorption by 540. So this is the palette, this is the soft palette of a patient. So here, 415, you can see the capillaries appear very dark, 540, you can see that you don't really see the capillaries particularly well, but you see the venules. And here, just for, again, for illustrative purposes, 600, which is a red light, which is a much higher wavelength, goes deeply and actually highlights the deeper veins. So that's why they use 415 and 540, because it highlights the superficial vasculature of the GI tract. And why do they call it narrow band imaging? It's because they also further filter the light in terms of the wavelengths, because they're generally distributed normally like this, but they filter out the superfluous wavelengths, so it's much more narrow, and that filtering and making it truly a narrow band improves the contrast that you see. So this is both 415 kind of wavelengths, but this has a bunch of extra wavelengths kind of at the margins, if you like, at the light, and here it doesn't, so you can see the contrast is much higher. So that's why it's called narrow band imaging with Olympus. So when NBI was released, then there were a whole bunch of NBI classifications that came out in terms of describing the vasculature and the surface of the GI, GI neoplasia. So there's the Sano classification, GK, Hiroshima, Showa. So a lot of classifications that came out, which again, they're all great in their own right, but became very confusing for endoscopists in terms of what to use and what they mean, especially for Western endoscopists, which taken us a fair bit of time to adopt optimal diagnosis. So as a result of that, and the result of the confusion, particularly for Western endoscopists, they came up with the nice classification to try to simplify things and make it a lot more practical for endoscopists. So you have type one, type two, and type three, and overall, pretty good accuracy in the studies that have been done. I'll talk a little bit about that in a second. So we're just going to go over them. So type one, you kind of look at it grossly, and generally it's the same color as the background or even lighter than the background mucosa. In terms of the vessels, you may not see any vessels at all, or you may see some lacy vessels going through the lesion, the surface pattern. So you may just see little dark spots or white spots, and I'll kind of go over what those are shortly. But this basically tells you it's a hyperplastic or serrated lesion. So it doesn't distinguish between serrated or hyperplastic. Dr. Lam's going to talk about that in a little bit. Type two is your typical adenoma. So it tends to be darker than the background mucosa because it's hypervascular. You can see those brownish vessels, which are highlighted by the 415, 540 wavelengths, and they're regular and repeating in their pattern. They have a regular caliber and distribution. And the surface, which is the white part, which is the epithelium lining those pits, again, has a regular surface caliber, distribution, and this corresponds to an adenoma. Type three, it can be darker in some areas, lighter in some areas, which are avascular. In terms of the vessel pattern, it's completely disrupted. You may have avascular areas. You may have large neoplastic vessels. The caliber is going to be all over the place in terms of the individual vessels and the distribution of the vessels. And the surface pattern will be completely absent in the area of cancer. So a good example here of a deeply invasive, although small, but deeply invasive carcinoma. So on that note, we'll go to a practice lesion. So this is a small lesion in the sigmoid colon here with white light and here with NBI. So if you had to choose the nice classification for this, I think most people were familiar with it prior. So hopefully now it's very familiar and everyone's has it solidified in their mind. I think everyone recognizes this as a regular tubular adenoma. You see the vessels are regular and repeating. The caliber is the same. You may have some slightly varying patterns, but the caliber and distribution of the vessels is the same throughout. The white part, which is the epithelium, again, you have regular width and distribution of it. So type two, a nice tubular adenoma. We'll move on to the next one. So nice two. Sorry about the little bit of a lag. So here's another lesion. This is also in the sigmoid colon, white light on the left and optical enhancement mode one on the right. And that's the equivalent of NBI in the Pentax platform. It uses similar wavelengths as the NBI 415 and 540. So if you had to choose there, so there you see again in this particular lesion, you don't really see lacy vessels. You don't really see vessels at all from this view. You see these little tiny dark spots. And that's just the area of the pit that you can just kind of barely make out. So this is a hyperplastic polyp. And in terms of distinguishing that versus serrated, Dr. Lam will talk about that in a bit. And then we'll move on to our final practice lesion here. So that was a hyperplastic polyp, as I mentioned. So how about this lesion? This is a small lesion that was in the rectum. And you can see here, white light here, NBI kind of close up. So if you had to choose nice one, nice two, or nice three. So I think most people think it's nice three and you would be correct. So you can see in terms of grossly when you look at it, there's some areas that are lighter than the background mucosa, some areas that are darker or hypervascular. If you look at the vessels, look here, there's a very large neoplastic vessel here, small vessel here. And the actual caliber of the vessels themselves is quite variable. The distribution, again, this area is quite densely vascularized. This is almost completely avascular. The surface, so the white part, the epithelium, you actually don't see it at all here. It's completely amorphous. You can see that as well here. So this is a deeply invasive carcinoma, which everyone got. So hopefully this helps explain to you why, you know, like you look at it, you know, it's a carcinoma, but now you kind of know why you intuitively know that. So hopefully kind of moving things to kind of a more conscious competence of knowing why you intuitively know what some of these lesions are. So the NICE classification is great, but it's not perfect. And some of the limitations are the studies that included polyps greater than a centimeter and having high grade or SM1 lesions, the accuracy is not great, 75 to 80%. And the level of high diagnostic confidence, again, not as high as we would like 50 to 75%, depending on the study you read. The NICE classification, again, we have three distinct categories and we know pathology is a lot more variable than three distinct categories. So you can't distinguish between low grade and high grade SM1 on NICE classification. You can't distinguish between hyperplastic and SSL. So there are some shortcomings of it. It is useful in many ways, but not perfect. So as a result of that, the JNET classification was developed and they tried to stratify the type 2 category to make it a bit more representative of what you encounter clinically. So you have type 2 is then broken up into 2A and 2B. I won't go into the, there's another subcategory to 2B and in terms of 2B high, 2B low, but it's not as widely used. So we'll stick to the 2A and 2B, but that stratifies things in terms of a low grade adenoma and 2B, which would be kind of high grade SM1 lesion. So trying to represent clinically what you see a bit better than the NICE classification. And this is what it is here. So 2A is basically kind of what you'd expect, kind of the NICE 2 lesion. So regular repeating pattern in terms of the caliber distribution of the vessels and same with the microsurface, the white part. So you kind of have regular repeating microsurface, whether it's tubular, branched or papillary, these different kinds of patterns, but the caliber and the distribution is normal. Whereas 2B, you start seeing some variability in it. So in terms of the caliber, there's some variability in the vessels. There's some irregular distribution. Some areas are a bit denser than others in terms of the groups of vessels. The surface pattern, you may have some small areas where you have an obscure pattern or again, some variability in terms of the microsurface. So some areas here, for example, the microsurface is quite irregular, but nonetheless present. And some areas where maybe you even lose it a little bit. And again, very contrasting that to a deeply invasive lesion, which we saw previously. So I'm going to jump in with my question here before. Yeah, sure. Of course. There's a question from the audience here about whether optical enhancement modes, how they compare to chromoendoscopy or they say specifically dye. Yeah. And if so, you know, when should you be using chromo or spraying dye to look at? So they look at different things, right? So image enhanced endoscopy, particularly with NBI or BLI or optical enhancement, basically will highlight the surface and the vasculature. It will not highlight the pit pattern. So it depends on the classification that's being used. One of the issues with chromo is that it's not as widely available. It's a bit more tedious to use, but so far overall, the most accurate optical diagnosis in terms of that in the literature is the pit pattern. But again, it's not as practical. So generally most endoscopies now will use image enhanced endoscopy with NBI, BLI or optical enhancement mode. And they'll use one of those classifications, whether it's NICE or JNET, if you have magnification. So it depends on the availability of chromoendoscopy, which again is not widely available in North America as it is in Japan in particular. And it's not as practical in terms of the time that's required, particularly if you use crystal violet. That takes a bit more time to use as compared to indigo, where you just spray and look. Crystal violet takes a bit of time. You have to wait for it to stain, then wash off the excess. So generally most people use image enhanced endoscopy in the Western hemisphere. Indigo carmine in some places is readily available, fairly easy to use, and may help you in terms of your optical diagnosis. But to do accurate pit pattern, particularly of the more advanced lesions, so the 5i and higher, you do need crystal violet. So yeah. So a follow-up on that question then, you know, indigo carmine is not readily available here in the West. And I just wonder what your thoughts were with regards to the more often used methylene blue. So it will stain the cytoplasm of the lesion. So in terms of pit pattern diagnosis, it's not really, it's never been really used for pit pattern diagnosis because it's not like crystal violet where, for example, stain the epithelium and leave the pits open, or indigo carmine will pool in the pits. And I'll show some images of that shortly. So methylene blue is not particularly helpful for pit pattern diagnosis of the colon for adenomatous lesions. So I guess it's in the setting of IBD, it's methylene blue is used mostly to detect actually a change, right? Like surface change as opposed to... To characterization, yeah. So it's for IBD, and again, I think the literature is coming out more that chromo is not superior to kind of high definition examination, but it's used more for a macroscopic examination in terms of methylene blue, for example, for IBD, whereas crystal violet indigo is used more for the microscopic examination of colorectal lesions. And a follow-up question from the audience there, I think kind of getting the same thing, but the question was, does MBI actually help with pit patterns? And you can correct me if I'm wrong there, Rob, but it's more, MBI is more looking at highlighting the vasculature and the surface epithelium, and really it's tough to comment on pits without using chroma. Correct. So NBI, and I'll show a slide on that in a minute, NBI is generally not used for pit pattern diagnosis. You can see the epithelium, which is the white part, and for some of the lower caliber or lower pit patterns, such as type 3L or type 4, you can extrapolate from the NBI, but you're not really looking at the pits. So NBI is not for pit pattern diagnosis or not for pit pattern examination. NBI is for surface and vasculature, and indigo, crystal violet is for pit pattern. So NBI, not for pit pattern. Nice. And questions are rolling in now. There's one more asking about in your reports, and I think Eric and Neil should answer this as well, but how do you guys describe your polyps? Do you put in NICE? Do you put in PARIS? I think the answer is probably yes to both, generally from what I've seen. You guys generally put in all the classifications you can. Correct me if I'm wrong there. Yeah, I use PARIS and JNET when I have magnification. If I don't have magnification, I'll use PARIS and NICE. Yeah, you ideally want to give as much information as you can, right? Location of lesion, size of lesion, as Rob mentioned, granularity or the LSTG classification, or LST classification, and then the optical classification that you've described. I think those are all pretty standard components now of like a large polyp or a complex polyp resection report. Yep, same here, right? Mostly PARIS and JNET, right? So, we'll kind of quickly get through the last few slides. So, this is a adenoma here in the descending colon, and you can see now with magnification, it will show you what the JNET2B is as compared to the JNET2A. So, you can kind of distinguish between the JNET2B and the JNET2A. So, there's the JNET2B. So, you see a bit of variability in terms of the vasculature and the surface as compared to the 2A. So, a nice lesion that demonstrates the difference between the two. The advantages of JNET are overall in the studies, their improved confidence rate, and that's probably because of the ability to use magnification because JNET requires magnification and because there's more categories. So, it's more likely to reflect the pathology, and that pathology is continuous, and we're the ones who are creating these categories to put them in. The drawbacks, again, whether or not you have the availability of magnification, the accuracy of JNET2B in predicting high-grade SM1 is also, again, not perfect. So, the recommendations are if you have a JNET2B, if available, you use crystal violet and pit pattern analysis to improve the accuracy. And that's generally what's done in Japan, may not be done in the West because we generally don't have the availability of crystal violet. So, this hopefully will tie things in in terms of what the microscopic exam is. So, this is a lesion here with indigo carmine. So, here is indigo carmine pooling in the pit. So, if you look at here, this is where the indigo is, and that's what you're seeing here. And that's where you would see crystal violet, and I don't have an image here with crystal violet, but if you remember before, it will look more kind of like a gyrus pattern, and it will stain this here and leave the pits unstained. NBI, so NBI shows you the vasculature here in the area where the epithelium is very thin. So, this is where the vessels are. So, you can see here in this area where this red vessel is, that's what NBI is going to highlight. And you can see that here, all the areas that are dark, that's these areas, that's what you're looking at. And the white parts that are surrounding the vessels are these areas that are lining the pits. So, hopefully that kind of try to kind of solidify this in your mind, and then you'll really know why NBI is not good for pit pattern analysis, and why indigo carmine, again, you can see the pits quite nicely, and crystal violet as well, and what the different classifications are based on, and what the image enhanced endoscopy shows. So, NBI, BLI shows the vessels that are here, and shows you the surface, does not highlight the pits. Indigo carmine pools here, shows you the pits very well. So, hopefully that kind of answers things. And this is something called the intervening parts, kind of the unit, you can think about it. So, that's the intervening part here, kind of one, almost think of it as like almost like one villus, kind of as a unit, and you can see that here at the bottom as well. And again, notice that you can't see the pits really at all with NBI, but you can extrapolate based on the white, potentially what the pits are. So, this is I think the last case, and then we'll move on. But white light, this is an ascending colon lesion. If you look at it with white light, and then we'll go close and look with BLI and magnification, and we'll see the surface, which is the white part, so the epithelium lining the pit, and then the dark part, the vessels, which are just underneath the thin part of the epithelium. So, you can see that there quite nicely. But again, see if you can appreciate the pits here. You can't really see them particularly well. You can kind of get a hint of them in between the epithelium, but very difficult to see the pits. Whereas here with indigo carmine, they're pooling, the indigo carmine is pooling in the pits, and you can see them very, very easily and accurately say which type of pit it is. And notice in the middle there, you can kind of see the vessels as well, little reddish areas. And that's, if we used NBI, what you'd see highlighted very well. So, if you had to guess in terms of the pit pattern, so I kind of gave it away a little bit earlier, is this a type 2 pit pattern, 3L, long, type 4, or type 5I? Just while we're doing this poll, we're up to just a question from the chat there. The question was about using JNET for just NBI or can use it for BLI. Generally, I think when you're saying NBI or BLI, you're considering them equivalent optical modes or only one, right? It's just different manufacturers' versions. Yeah. So, there's very subtle differences in terms of the wavelengths, but they basically highlight the same. They generally use similar wavelengths anywhere probably between 405 to like 415 in terms of the blue light, and then 530, 550 in terms of the green light, but they all use the same, generally same principles and highlight the same structures in terms of the surface and the vasculature. So they are interchangeable. Different manufacturers will tell you different ones are better, et cetera, but they highlight the same structures. So we have a bit of a split here. So some say 3L and some say type 4. So you can see, I see where the 3L is coming from. There's some areas where there's these long appearances, but if you look at it overall, it's kind of a gyrus type appearance. It looks like a brain. So this is actually a type 4 and it would be a tubulovilous adenoma. But if you looked at this one isolated tiny straight one here, you could say, yeah, that's 3L. But if you look at all of them together, it's kind of a gyrus type pattern and it would be type 4. All right. So we'll skip through. And for time's sake, we'll just quickly go through this poll. But I kind of gave you the answer. So because it's type 4, it's actually a tubulovilous adenoma. There was no irregular microsurface or microvascular pattern. So if you look here on the bottom right hand corner, it was actually a JNet2A. The vessels and the surface are pretty regular. There's no variable caliber. So this ended up being just a tubulovilous adenoma without high-grade dysplasia. So again, a bit of a split between these two. This is not unreasonable and I think most endoscopists, there may be a bit of discussion about it, but looking at it here, I think it's pretty consistent with the TVA and that's ended up what it was. So just sorry about the lag here. So why do we care about optical diagnosis? This was just a study from screening colonoscopies and in terms of 3,600 colonoscopies, about 92 T1 cancers were diagnosed. So just showing you that about 39% were recognized as cancer. Of those, 11% went on to require surgical resection. The ones that ended up going for surgical resection, the ones that weren't recognized as cancer, a lot more of them went to surgery and that's usually because they had a piecemeal resection. So this study basically just says that we care about optical diagnosis because when we recognize superficial cancers, we're more likely to give them the appropriate treatment and avoid unnecessary surgery. And that's essentially what it's saying. And also saying that we're not great at detecting superficial cancers and there's room for improvement. So back to the cases in the beginning. So this lesion, so again, for time's sake, I'll just go over it with everyone. Tubular adenoma, so low-grade dysplasia because of the regular surface and vasculature in terms of the distribution caliber of both of them. So low-grade adenoma. And this lesion, this ended up being a massively invasive carcinoma with lymphovascular invasion and a couple of areas of poor differentiation. And the patient wasn't a candidate for any further treatment, but it was removed locally via ESD for reasons of multiple comorbidities and inability to have a surgical resection. But you can see that there's a completely obliterated surface and vascular structure here, avascular, amorphous area in terms of the surface. And then again, the vessels quite irregular in some areas where you can't actually see the vessels at all, but the surface is definitely amorphous and irregular. So deeply invasive carcinoma, JNET3, NICE3. Let's skip that. And the last one, that was the other rectal lesion. So this was a LSTG mixed type, so granular appearance and at least one dominant nodule. It also had this slightly depressed area here, so a 2C component. If you look at the areas around it, it looks pretty benign. This looks JNET2A, JNET2A, JNET2A in terms of the appearance. So based on that, and you just looked at those areas, you may think this is a low grade adenoma. However, if you then focus on that one depressed area and look at it closely, you'll see that the microsurface is quite irregular and in some areas a little bit amorphous. And I actually thought when I examined it, that it was a carcinoma. So this area here, the depressed area. So you can see some areas actually that were amorphous. And I thought this was a deeply invasive carcinoma as well, but in discussion with the patient and at multidisciplinary rounds, we decided to initially chart the local excision and depending on the pathology, he is still a candidate for further treatment. This ended up being high grade dysplasia. But if you look at it in terms of the high risk features, it was an LSTG mixed type with a dominant nodule, so roughly 15% chance of subucosal carcinoma. Then if you looked at it with your magnification, you can argue at least a JNET2B, if not a JNET3. So there's some debate on that in terms of based on the surface and the vasculature here and here as well. But definitely a high risk lesion, if it's going to be attempted, should be in one piece, should there be carcinoma that it's accurately assessed. But this ended up being surprisingly only high grade dysplasia and completely resected. So, sorry, when you're describing lesions in LST, there's a question of whether you apply the Paris classifications as well, for example, would you say that's a 2C component of that LST? Yeah, so in terms of that lesion, so the way I would describe it, it's an LSTG mixed type, if you want to use the Paris part of it. So if you look at the periphery, there's slight elevation, but most of it was a 1S lesion. So you'll generally pick the most predominant feature first. So it'd be a 1S plus 2A plus 2C lesion, if you want to describe it that way. And again, there's going to be debate about in terms of, well, is it a 1S plus 2A plus 2C, or is it a 1S plus 2C plus 2A, which really doesn't make a difference clinically. You're really just trying to capture the different morphologies in your description. But generally, I'll use those in conjunction. So in the reports, again, I'll use it as much as I can in terms of the information of the macroscopic exam, as well as the microscopic exam. So if someone reads it, they can try to, if we don't have good photo documentation, depending on where you are in terms of whether it's digital or print, to try to get as much information as possible, particularly the high-risk features. All right. Okay. Well, thanks, Rob, for inviting me, and thanks for the introduction, Doug. We too are expecting great things from you. And welcome to the fellows, the ASG fellows. So what we're going to talk about in my section is really that of the SES-ulcerated lesion. And I'll show the first video here, courtesy of Rob. And so you can see here that there's something that's different than compared to the adjacent mucosa. We'll just get an appreciation of where the borders might be. Just sort of think about where the borders might be. Using image enhancements maybe to see this. And then a little bit more detailed look at the center of this lesion. I think there's a poll for this, Doug. Yes. Okay. Great. Sorry. So as far as the poll is concerned, we have this lesion here. Looks a little bit different than the ones that we've seen so far. So we have A, low-grade dysplasia, B, high-grade dysplasia SM1, or deeply invasive carcinoma. So we'll have the poll up here. I think on the actual poll, we have a no dysplasia category. Oh, okay. Yeah. No cytological dysplasia, unsuspected dysplasia, and deeply invasive carcinoma. Good. Right now, 50-50. All right. And there. Great. That's good. And then we'll go to the next one. So we're talking about CES-ulcerated lesions. These lesions have been described more recently in the last several decades as something different than the usual adenomas that we see. And they have been shown to result in colorectal cancer through a different pathway, a serrated neoplasia pathway, which involves a BRAF mutation as opposed to the standard APC mutation that we see with traditional adenomas. And it accounts for a fair number of colorectal cancers, approximately 15 to about 30% actually, and mostly are seen in the proximal location, ascending colon in the cecum. And why are these lesions warrant a closer look? Mainly because there's a significant proportion of interval colon cancers in between colonoscopies that we detect these colon cancers, these types of colon cancers from the serrated neoplasia pathway. And it's hypothesized to be due to inadequate detection or inadequate resection. So if you take a look at the documentation of CES-ulcerated lesions, these lesions have been described probably for the last 20 years. And they've gone through multiple different ways of describing them. And we always know about these innocent demeanor polyps in the rectum. But these CES-ul lesions were quite a bit different. If they're found on the right side, they tend to be larger. But histologically, pathologists used to describe them as hyperplastic polyps. And that unfortunately came into the mindset that these lesions are actually benign as the left-sided demeanor polyps. The problem with these CES-ul serrated lesions are also that we can only describe them morphologically through the current schemes that we have. And that is Paris classifications. We can use the Paris classification to describe the morphology. But as you saw in Rob's talk, that there is an association with invasive cancer to a certain morphology. That doesn't apply to these lesions. Similarly, J-net classification, we're looking at J-net 1, which lumps hyperplastic polyps with CES-ul lesions, CES-ul serrated lesions. And so you really can't make that distinction on that basis. And of course, the KUDO classifications, the pit pattern, typically a type 2 pit pattern or the stellate morphology of the pits, also very close to many of the hyperplastic polyps. So it doesn't really suggest that these lesions can in fact have a benign morphology. They are, they have, they're in a category unto itself. And unfortunately, these CES-ul serrated lesions have also undergone a confusing nomenclature over the years. So decades ago, they were called hyperplastic polyps. And, you know, we'd see these large hyperplastic polyps on the right colon and the pathologists reported as hyperplastic polyps. But it really doesn't adequately describe these lesions. And because we know that they progress onto cancer, the next iteration of the nomenclature is that they were CES-ul serrated adenomas. However, that's also not adequately descriptive as well, because not all CES-ul serrated lesions harbor dysplasia. And finally, they're also called CES-ul serrated polyps. And because polyps, of course, you know, end up in cancer in many cases, but many of these lesions are actually not protruding out very much. And in fact, many of them are flat. So the proper term really now is CES-ul serrated lesions. And just need to be aware that some of the older pathology reports sometimes will have these other types of nomenclature there and just to be aware of that. Where it is especially important is the serrated polyposis syndrome, where the World Health Organization updated it in 2019 to describe a syndrome where patients have these CES-ul serrated lesions and progress rapidly onto cancer. And the two criteria is that if you have more than at least five serrated polyps, proximal to the sigmoid colon, and at least two of these lesions are greater than 10 millimeters in size, right, and this is over time as well. So if you have a patient who has one of these lesions, that's 10 millimeters, then you need to continue to follow patients and they could still meet the criteria. The second criteria is that if you have more than 20 serrated polyps of any size, distributed throughout the colon, and that's the diagnostic criteria for serrated polyposis syndrome. If we were to see how common these CES-ul lesions are in the general population, in the screening population, screening colonoscopy population, about one percent of patients in our province, we have a FIT-based colon cancer screening program, and those patients who have colonoscopies have been found, about 14 percent will have CES-ul serrated lesions. Okay, so here we will take a look at a video here. Here we have a polyp and we can see that there's, it's slightly elevated above the rest of the surrounding mucosa. It is a same color or slightly paler than the surrounding mucosa. The border in this particular one is quite distinct, however they can be quite subtle and therefore will take a lot of time in order to identify it. This, with some acetic acid spraying, really accentuates the pit opening of this serrated polyp. What's more, what's also important to note where these polyps are is really the location of, within the colon, the size and the border. Surface features, many of them will have a mucus cap on top of it. Okay, and pit pattern once again is shown here with this picture here. And NBI features, the lesions themselves, the CES-ul serrated lesions, tend to be quite avascular and so on NBI you'll feel, you'll see some wispy type of vessels as opposed to the vessels that you would see more in adenomas. Okay, so why is it, once again, why is it important to detect and distinguish these lesions, these CES-ul serrated lesions? Mainly because they are quite subtle. They contribute to a high number of colon cancer and missed colon cancers, and the management is subtly different than traditional adenomas. And to just give you an idea, these CES-ul serrated lesions that have no cytologic dysplasia can be removed with a piecemeal cold snare, with or without subucosal injection, which there's emerging data for adenomas, but I guess Neil will talk about that later. So a different beast entirely is the CES-ul serrated lesion with dysplasia, and really what you're looking for here is changes in the homogeneous appearance of the CES-ul serrated lesion. Another thing to keep in mind is that dysplasia increases once the polyp gets larger, greater than 20 millimeters. If in your CES-ul serrated lesion you have different morphological features, such as a 1S component or nodules, right, these are also ones that you need to look out for dysplasia. And if you look closely, look for vascular irregularity and mixed J-net classifications within the SSL itself. So if we're to see here, here's several slides of SSLs with dysplasia, and you can see here the edges of the CES-ul serrated lesion. However, on the inside you see a bit of a nodule here, and if you get closer, somewhat excavated or depressed in this area here, right. Similarly, in this we have a CES-ul lesion, but generally different morphological features going on, right. The final picture here, we see some larger vessels, which are likely tumor vessels in this CES-ul serrated lesion. Okay, so if we take a look at this case, and we'll put your diagnostic, optical diagnostic charts to the test here. I'll just run that video. So the poll is, is this a SES-ulcerated lesion with no cytologic dysplasia, suspected dysplasia, or deeply invasive carcinoma? So let's see the poll. Okay, not bad, not bad. So we'll advance to the next slide here. Most people do say that it's no cytologic dysplasia. It is a larger lesion, that's for sure, right? But yes, this location is in the cecum. It's 30 millimeters in size, slightly raised, so it's a 2A morphology, not applicable in terms of granularity because that applies to adenomatous polyps and not to SES-ul lesions. And the optics are typical for a SES-ulcerated lesion without dysplasia. And just sort of want to show you a case that I was referred to remove a large SES-ulcerated lesion, and just want you to give you a sense as to what these look like. You can see here, there's the difference between the normal mucosa here, and this cloudy, wispy vessels throughout this SES-ulcerated lesion. And as we come down towards this area here, this polyp was in the ascending colon, it was roughly 40 millimeters in size. And we see here that the SES-ulcerated lesion does go up higher along this fold, and there's a 1S component to it, perhaps even a bit of a depression at the base there. So a slightly different pole, it would be, sorry, slightly different pole, is really to write down what are some of the concerning features that you see in this polyp. Size, yes, so it's a 40 millimeter polyp, it's quite a large size, so there's a higher chance of it being a dysplastic SES-ulcerated lesion. Depressed area, right, yep. Nodule, oh, okay, this is like a word collage. Okay, the mucous cap, yes, there's a mucous cap, that's a feature of SES-ulcerated lesions themselves, right, it does not necessarily result in a higher risk of dysplasia, right. The nodular area, yes, very good. Depressed, yes, yes, right. Okay, size and depressed, it seems like those are the two main things, very good. So it turns out that this patient had a biopsy of the nodular area and of the slightly depressed area, and it turned out to be a malignancy, had no carcinoma, and when the patient went for surgery, it was actually a T3 lesion. So even something that looks like this was actually a deep invasive malignancy, which was surprising, but can happen in these lesions. And Eric, when you're describing these lesions, there's a question from the chat, do you use the LST classification? Usually not, right, my understanding is that's for adenomous lesions. Yeah, that's for adenomous lesions, because morphologically they do not present in that way, right. And once again, the ways that we describe them through Paris classification is really based on morphology only. So if we say Paris classification 2A lesion, it's because it is raised no more than 2.5 millimeters above the baseline mucosa, but it has nothing to do with the subsequent chance of them having dysplasia or cancer. Okay, and so I think that that wraps up my segment there, and on to Neil. Um, so yeah, so thanks, Rob, for inviting me. Me and Eric give talks all the time together, and then it's great to see Doug again, who just left us. So, you know, I think that you guys had a great opportunity to, you know, sort of embrace optics in different ways. This is very much a westernized approach to endoscopy or optical evaluation. You know, one of the, it'd be interesting to know what Rob and Eric do, and Doug, but for me personally, obviously location, size, all that sort of stuff, a big stratification that I commonly do is whether or not a lesion is flat versus nodular. That makes a big difference to me with respect to how I approach optical evaluation, and as Rob has highlighted, it also has an implicit effect on the risk of cancer within the lesion, and so this was a study that we published back in 2021 showing that in flat lesions is where we find that optical evaluation actually has very good performance, and the chances of you missing a cancer is actually quite low, and that, again, speaks to Rob's point that, you know, the LSDG homogeneous or homogenous lesions have an intrinsically low risk of cancer, so one, the chance you're going to find a cancer in that group is low, and two, likely because it's flat, if there is an irregularity on the surface, you're going to have a much higher chance of spotting that irregularity or demarcated area, which is sort of a unifying feature of all of these classifications that you've heard, whether it be NICE or JNAC, KUDO, GKACE, you know, SHOIA, SANO, Hiroshima, they all sort of unify around that concept, whereas, you know, where we run into trouble is nodular lesions, and this sort of speaks to that meta-analysis that Yara Bakso, I don't know, Rob, if she's still a fellow in the Netherlands, but she might be, she might be a very senior fellow now, but she's done a ton of studies, she did optical, she did that meta-analysis, she's done a ton of great work when she did her PhD, but again, it's just the fact that it's these nodular lesions that really give us trouble, and this is an older study, the next one, this was done before I got to Australia, and I tried to click over, maybe I'll try again here. I can, I'll do it if it's, if it's not working. Yeah, so this is this concept of like invisible or covert cancer, so this was a study, give or take, of around 2200 lesions, a little bit more than that, and, you know, what they had done was they said, okay, well, we're going to take away all of those, you know, classical high-risk features, either, you know, advanced pit pattern or alternatively depressed components, and then subsequently stratify lesions based off of location with proximal dystopia based off of rectosigmoid versus higher than that, and then also on the pairs classification, the concept of granularity, and again, what they found was is that there are intrinsically high-risk lesions, so, you know, this is maybe a study that I think probably would be nice to potentially redo as we now have more availability of classical magnifying endoscopy throughout North America, but what they found was is that it's really these sort of non-granular or smooth lesions that have nodules that it's where you really get into trouble, and it doesn't matter where in the colon that is, those are concerning lesions that, you know, we'd really advocate to do an on-block resection. Now, obviously, every endoscopist has different approaches with respect to what's going to be their threshold for on-block, but definitely these are lesions you should definitely consider for on-block resection, and then the other lesion are these, you know, as Rob mentioned, these LSDG mixed-type lesions or lesions that have granular morphology but have both like a flat and nodular component, and that's a classic morphology that we see or a classic grouping of lesions that we see in the rectum. So, this is pretty hot off the press. This is at CGH now, and this is just an extrapolation of what I just mentioned to you. So, you know, when you start using, you know, sort of demarcated areas, which are suggestive of advanced pathology, and alternatively, if you start applying that sort of covert risk strategy, and this is specific to the rectum, whereby lesions that have that sort of 2A plus 1S granular morphology, if you select those patients for an on-block resection ESD, and then otherwise, the remainder of lesions can undergo EMR. This is actually a very effective approach for trying to avoid missed cancers, and so this is a study of approximately 480 lesions, and in the prospective, a completely prospective study, but in the era of the selective resection algorithm where ESD and EMR was being used, we actually only missed one cancer. So, that sort of gives you a little bit of a different lens on different approaches for optics. Now, you know, in a lot of areas, like, for instance, you know, in Vancouver now, I don't want to speak for Eric, but a lot of times we're doing a lot of ESD in the rectum, and that's just the culture that we have. We have a very prominent colorectal surgery group, and so I'll be honest, I just want to avoid any piecemeal resection of cancers in the rectum, to be honest. So, let's see if I can do this here. So, you know, this is a lesion in the rectum. Did it stop, or can you, is it moving for you guys? It's not moving for me. I'll let you do it. Yeah, so this is a lesion in the rectum, and, you know, I guess I don't want to sort of, because I think there's a survey after this, but, you know, this is sort of a classic approach to optical evaluation in the West, you know, overview of the lesion, you know, interrogation under white light. This is an HQ 190 scope, and so it has near focus or dual focus. So, the optics are this, this video should be coming to an end pretty close here, but based off of that video, what does everyone think? Is this, I think no dysplasia is referring to, is this a sessile serrated lesion? You know, is this a low risk lesion, like an adenoma with dysplasia? You know, is this something that's higher risk? Is this something that you should, you know, be thinking about on block resection techniques, or is this something that you sort of want to back off and say, well, maybe I need to call the surgeons in, because this is a high risk lesion that I probably can't help this patient. Okay, everyone thinks low grade dysplasia. Eric, Rob, you agree? Doug, you agree? And then, you know, we're going to, yeah, you know, we're going to sort of avoid, you know, resection modalities, but yes, could you piecemeal resect this? I don't think it's unreasonable. It depends on sort of what's available to you locally, but I think would anyone, you know, slap your wrist if you wanted to do an ESD? No, I don't think so. How low was that down to the anal verge there? Yeah, so that's right to the dentate. So yeah, I said rectum, 35 millimeter, and that's a rough estimate by the size of a snare. That's a lot of what studies will do is you'll, even if you're doing an ESD, you can open a snare to give you a rough estimate, pre-injection, morphology, 0-2A or LGE, granular homogeneous type, granular morphology, NICE and JNET for research purposes, I commonly do both. And then, you know, this would be classified as a low risk lesion based off of covert risk criteria. So yeah, benign adenoma. And so here's another lesion. Rob, do you want to try to play? Sure. So if anyone in the chat wants to have a go and guess at what I think that what they think this is, feel free to put it in the chat. Don't feel obligated though. You know, to give you a little bit of a prelude, even amongst the three of us, we can have discordance amongst what we see. But interestingly enough, at the end of this, we all sort of agree on what we think should be done for this lesion. So this is in the rectum. Is that right, Neil? Yeah. This is also in the rectum. So next slide. Sure. I think the next slide issue I don't have, but well, maybe I do. I don't know. Perfect. Okay. So people are sort of putting things out there, but again, is this a Sessile serrated lesion? Is this a benign adenoma? Is this a high grade or a higher risk lesion? Or is this a lesion that you say, no, no, I don't want to touch it. Yeah. And so I agree. I think so. So I think Eric touched on this. The easy thing, like I find the no brainer solution for stratifying serrated lesions versus adenomatous lesions is if you see all these big nodules, you know, it's an adenomous lesion. You know, you don't have to really worry about sessile-sorted lesions, unless you think it's a sessile-sorted lesion with dysplasia. Okay. So let's see what I wrote down. I think we modified this as we went through our slides. So yeah, so rectum, large lesion, 2A plus 1S, granular, you know, nice 2. And again, this encompasses both chain and 2A versus 2B. And even if you say that it's not a 2B lesion, the important thing is it's just based off of the morphology of the lesion, this would definitely be a candidate for ESD because of the fact that you're classifying as high risk for covert cancer, right? You know, and multiple studies have now shown this, like Al Iropechi has done a study on this that I think is published in CGH. Obviously, Michael Burke has done a ton of stuff on this as well, and some of those recent studies that I showed you. Okay. So I think I'll return it back to Doug. I think Doug's gonna bring it home. I will do it, if that's okay. So just in summary, kind of the approach to your colonic polyp assessment, first do your macroscopic assessment of the lesion, kind of look at the size, pairs, classification, the LST subtype, if applicable, then looking for high risk morphologic features, which we talked about, like fold convergence, spontaneous bleeding, some of the chicken skin mucosa, demarcated depressed area, then you do your microscopic exam based on what's available to you, NICE, JANET, and PIT pattern if you have a chromo available. So basically take it like your history and physical of a patient. You may have a spot diagnosis as soon as you kind of see the patient, but you're gonna do your history, your physical, your laboratory investigations, radiology, take all that information so you can kind of make the most accurate diagnosis and not miss some of the more rare things. And that's the kind of same approach you take with colonic polyp assessment. And the polyp assessment will improve characterization so you can tailor your therapy better to the pathology. And if you're gonna biopsy something, which we generally recommend not, but you're gonna take a targeted biopsy of something you think is an invasive, a deeply invasive carcinoma, if you're gonna biopsy, if you're gonna EMR, you're gonna ensure to remove the most invasive area on block, depending on the availability of ESD or not having the availability, knowing when to refer for ESD, depending on, again, what you see and when to refer for surgery, and also will help predict difficulty in terms of lesions. So for example, an LSTG homogenous lesion that's three or four centimeters may come off very quickly and easily versus say a non-granular flat or an LSTG mixed type, depending, is gonna come off generally a bit more difficulty, generally more difficult than say a granular homogenous. So you do your macroscopic assessment, microscopic assessment, and those are some of the things we chatted about, and always follow up your pathology and compare it to your endoscopic diagnosis, see where you were right, see where you were wrong, and when you're wrong, go back and figure out did you miss something optically and try to constantly improve your optical diagnosis. Thanks everyone, and thanks to the group and to the ASGE for allowing us to do this talk and chat with you guys. So now we'll move on if there's any kind of questions or stuff for discussion. I know we're running late, but there is one question I held from the chat there. We didn't talk a lot about KUDO that much, but there's a question about PIT pattern five being listed under the ESD, like the AGA ESD guidelines as an indication for ESD. And the question was, should it be excluded as an indication as it can predict deep semi-coastal invasion? Well, so that's the whole thing in terms of N, so 5N, and that's very accurate in terms of deeply invasive. 5I, there's gonna be a proportion of them that are gonna be deeply invasive, right? So 5I, there's also stratification of 5I high and 5I low, which also, again, kind of makes it a bit more accurate. But generally, the reason it's an indication is because you're gonna avoid surgery in a fair number of patients that have superficial carcinoma. If there ends up being high-risk features, you don't burn any bridges. The patient can still go on to have an oncologic resection. So I think it's important to, these high-risk lesions in terms of planning for should they be invasive. If there's a lesion that has multiple high-risk features and you're uncertain in terms of if there's gonna be deeply invasive or other high-risk features, stage it appropriately and get it done in a timely manner such that should they require oncologic resection, you don't cause significant delays. But definitely, I think 5I is an indication. And yeah, I agree with that kind of recommendation. I had a question maybe for Eric and Neil since I've just started doing this locum here, specifically about SSLs. I've noticed that the pathologists here seem to call a lot of hyperplastic polyps when I'm taking them off, even in the right colon, transverse colon. And so I'm wondering if you get that path report, are you counting those SSLs? Like, are you doing surveillance based on that or do you believe in hyperplastic in the right colon? Yeah, I mean, the hyperplastic polyps that we usually see that are benign are the ones that are diminutive on the left side, right? And those have always been universally known to be that, to be benign. However, in the right colon, it's quite a bit different, right? And so even, like, I would say, if you removed a right-sided SSL, right, and it's reported as hyperplastic, it's not a diminutive polyp, right? Like, I mean, the one that you removed, it's probably a bit bigger than that, right? And just the location itself is more concerning, right? So I would call it an SSL. Yeah, I agree. It depends on what you're taking off. And sometimes it's not gonna have implications on your surveillance. It's not gonna have implications on serrated pliposis syndrome because it's serrated class lesions for that diagnostic criteria. And so, yeah, I think anytime you have, oh, for sure, like if it's a large hyperplastic lesion on the right side, I probably will chalk it up to a SESS ulcerative lesion. But normally I'm just touching base with my histopathologist and, you know, potentially even touching base with a GI pathologist in those scenarios to refine that diagnosis. Right, I guess a follow-up question on that is this serrated polyposis syndrome, Rob, Doug, and Neil, how many times do you make that diagnosis on the index colonoscopy as opposed to following somebody and then once they meet criteria, then they have this SPS? Do you mean like a patient referred for a large polyp and like how often will I subsequently make the diagnosis? Yeah, yeah. I think it depends on your approach. A lot of times, depending on who's referred to colonoscopy, I focus my index colonoscopy on the endoscopic resection and then I commonly use my surveillance endoscopy for subsequent diagnosis. Now, as the frequency of how often I identify SPS in patients who've had a large polyp, I couldn't quantify that for you, but it's definitely not uncommon. Roughly, I'd probably say at least 10% of patients I probably meet the diagnosis of SPS. So definitely be on your guard. If someone has a large serrated lesion, you should definitely be on the lookout for others. Yeah, I'd say it's definitely not uncommon in a lot of people who you get referred a right-sided polyp and then you end up finding a whole bunch of other serrated lesions. So I'd say it's a lot more common than I would like in terms of that they don't have a diagnosis of serrated polyposis, but they had a surveillance colonoscopy a few years ago, had a polyp, and now they have this big one that was found and they get referred to, and they definitely meet criteria and you end up just taking them as your patients afterwards anyway, but yeah. Yeah, I think once, like I've been in practice for quite some time that keeping track of these patients with CES-ulcerated lesions to then say, okay, now you're SPS, right? As opposed to, especially with the old reporting of it being hyperplastic polyp or CES-ulcerated adenoma, and then it just takes sometimes a couple of years to then formally make that diagnosis. Okay. Thank you. I have a question for you, Rob, if no one else has got questions. So going back to that original question, when would you recommend at an absolute minimum to do chromoendoscopy, or alternatively, like when are you applying chromoendoscopy? Do you use it universally because you find it's effective in all lesions? Are you sort of really reserving it for those lesions where you're concerned about an area or to stratify it? What's your approach? So right now, in terms of, I'll use it for my large lesions. And to be honest, does it make a difference in terms of my optical diagnosis the vast majority of the time? Because I only have the ability of indigo. Probably doesn't, because again, indigo is not great for 5i plus. It's good for everything up to type 4 pit pattern. And then 5i, you really need crystal violet to do it most accurately. And those are the recommendations as well in Japan. Basically, if you have a five subset pit pattern, you need crystal violet to assess it accurately. I really, in terms of what I'll do, it helps in delineation. I find a deletion, like it makes it maybe a little bit more clear in terms of delineation. And it will just kind of consolidate what I already think. But have I changed my optical diagnosis with indigo? Probably very rarely, but it sometimes highlights things a little bit better, particularly some of these very, very subtle, like 2B lesions, like pure 2B lesions. Definitely, it actually helps with the delineation of them, which they're not particularly common, the pure 2B or pure 2C lesions. But if I had crystal violet, I would definitely use it for these superficial cancers. And I think it's useful in that regard. But I think in terms of indigo, in terms of for superficial carcinomas, does it make a difference in terms of the accuracy? Probably very, very unlikely, to be honest. Okay, and then I feel bad because every single time that Rob and I do talks, I always ask him a bunch of questions. But here's another one. So Rob, what's your, I really struggle with this. There's been this description of the valley sign for diminutive adenomas. How do you distinguish the valley sign for diminutive adenomas versus the concerning area? Like nice, or nice, Janet, 2B, whatever. So the valley sign in the description in the paper from Doug Rex, it was all diminutive polyps for one, right? And in terms of their description was, it was again, a relatively like, I guess it's one, it's not really well demarcated in terms of like how well demarcated is that kind of slight depression. And it's not as a, the way they described to as a true depression, like a true 2C depression in a lesion is gonna be relatively more acute in terms of the drop, if you like. Whereas the valley is kind of a bit more subtle in terms of like, it's a slower kind of sloping depression as compared to a 2C depression. And that's the way they described it. But there was one of the other cases that I had where it was a small lesion, maybe about a centimeter, centimeter and a half, I didn't have time to show it, but where I had a true 2C component. And it's a much more, I guess, relatively steep is the way I describe it in terms of a steep depression compared to the valley sign in these kind of diminutive less than a centimeter polyps. And they described it more as a way to distinguish hyperplastic from adenomatous diminutive polyps. They found the valley sign was more common in adenomatous polyps. So, and I think at that time too, there was less in terms of high definition endoscopy, in terms of near focus magnification, in terms of being able to look at those areas a bit more clearly. But the answer is, I guess, in terms of the acuity of the slope, at least in the description of the papers and they're all less than a centimeter lesions. Right, yeah. I find it's just with these diminutive adenomas, you're also just heading your bets, right? The chances of these things being a cancer are like what, 0.04% now, based on some studies and some. I find it gets trickier when they get into, as you said, into that 10, 15 millimeter range, but normally you can distinguish them a lot better in that regard. Great. All right. Okay. Okay. So, I guess that will wrap it up. I think Marilyn has a few closing words. So thanks everyone for your patience. Thank you again to all our moderators and panelists for tonight's presentation. Before we close out, I just want to let you know to check out our upcoming ASG educational events. Registrations are now open and programs are available complimentary to our training members. The next ASG Endo Hangout session will take place on Thursday, September 1st, Complications of Endoscopy. At the conclusion of this webinar, you will receive a short survey and we would appreciate your feedback. As a final reminder, ASG membership is only $25 per year. If you haven't joined, please sign up. In closing, thank you again to our panelists and moderators for this excellent presentation. And thank you to our audience for making this session interactive. We hope this information has been useful to you. And with that, I will conclude our presentation. Have a good night, everyone. Thank you.

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