Good morning, everyone. It's always a pleasure to be part of this series. My name is Sophia Saleria. I am a GI liver and pancreas pathologist. I'm now going to share my screen. So I'm going to discuss for the next few slides, minutes about how a pathologist comes about to make a diagnosis of EOE. And with that context in mind, how we reach that from the differential, which is a whole host of other reasons why you could have eosinophils in the esophagus. What are the distinct microscopic features that we use, the criteria that we use to make this diagnosis. And then also as laboratory professionals, as pathologists, how we correlate with clinical findings, which is endoscopic findings and the patient history to ultimately reach that final diagnosis. So just a little review of what pathologists do. The pathologists are medical doctors that have subspecialized in laboratory medicine, where you're largely divergent into two main groups. Those that review primarily liquids, if you will, blood bankers, clinical chemistries, and all the analysis of CSF and other fluids. And then the other category is those that go into tissue. Amongst those are, of course, people that subspecialize in GI, such as myself. So once the tissue is procured from the patient, whether it's a resection or whether it's a biopsy sample, that tissue is then first and foremost fixed, usually in a formalin formula, where the further degeneration of that tissue is ceased. It then goes through a multitude of processes, mainly embedding the tissue in paraffin wax. And then from that point onward, it is cut into very, very thin microns and placed onto a glass slide. It's not exactly ready for review at that point because that glass slide is colorless and it needs to be stained. But just to go into what this looks like for the actual tissue, I'm always intrigued and surprised when I see this. So what you're seeing in this portion of the slide is actually procurement of biopsies from the esophagus. And you can see they're quite small. They've been fixed in formalin before they reach the lab. And then because they're so tiny, they will fall sometimes to the grates of these blocks that we have, that the paraffin is then embedded into them. So they're wrapped in usually some kind of dissolvable paper that dissolves when the paraffin is embedded, but also keeps them from falling through. But look at how this tissue then translates to the slide. So minuscule little pieces that you can see here. So this is just to show the progression of how small and how much the tissue really does shrink once it's procured from the patient. Now, again, as I said, prior to staining, the tissue is actually, when it's cut from paraffin, it's colorless. And so we require two main stains that are the mainstay of anatomic pathology, regardless of what your subspecialty is. And that is the stain that stains the nuclear features. It's a purplish stain, as you can see here. We call it a hematoxylin. And then the second one, which is a bright pink one, that outlines the cytoplasmic features. And so this is important in kind of producing a reproducible visual pattern for different anatomic sites. And this right here is the tightly bound epithelium, is squamous epithelium. And that's actually what the upper portion of the esophagus is lined by, squamous epithelium, very tight junctions like fish scales. Now, you can see a whole host of different types of inflammatory cells within the esophagus. Of course, the star of the show today is the eosinophil. And we see eosinophils in a whole myriad of conditions, not just in eosinophilic esophagitis, but parasitic infections, allergies of different kinds. And this is actually what it really looks like. So you have a high-power view here of squamous epithelium. Again, the nuclei that are purple, pathologists think in pink and purple, if you will, anatomic pathologists. And the nuclei with the pale pink cytoplasm. And then these very magenta-like cells with the almost binocular-shaped nuclei, if you will, are the eosinophils. They're very distinct. And in the top here, you can see that they have their granules. And depending on the degree of inflammation and how severe it is, they can be seen releasing those granules. And we'll talk more about why that's important. So just a review of basic esophageal anatomy. Very quickly, we start with the mucosa, which is up top, which is, again, where that tightly bound squamous epithelium is. These cells have very tight junctions. They're tight together. They're, of course, protecting the underlying structures from the luminal contents of food that's been coming in. Underneath that, we have the submucosa, where we kind of have the loose lymphatics and some submucosal glands, and then the thick muscular layer in the bottom that is responsible for the propulsion of that food further down the GI tract. For the purposes of EOE histology, we're going to stick to the mucosa because this is what we get from our clinical colleagues to review in terms of esophageal biopsies. And so I'm going to be bringing this image up over and over again, simply to kind of burn into your mind as to what a esophageal biopsy looks like that is A, well-oriented, B, has minimal to zero pathology. So we're going to start again just with some brief review of here is that thick squamous mucosa that you can see here. The proliferative compartment, which is the basal compartment you can see here at the base, this is where all the cells are kind of being produced. They're the most junior cells, if you will, and so the nuclei tend to be a little bit larger. And so it's by virtue of just the fact that this is where the regeneration is happening, it tends to be a little bit bluer, usually about three to four cells thick. And as these cells move towards the lumen, which would be here, they tend to have nuclei that shrink and cytoplasm that tends to be more pinker. And so it gets pinker as you go to the surface and eventually these cells are also sloughed off every so often as they reach maturity. And then right underneath the epithelium, you have the subepithelial tissue, which is not uncommon here to see some slight inflammation, which could be just some lymphocytes, even one or two eosinophils is okay. It's not uncommon. And then you have the submucosal glands here and then some lymphatics. And so you can see here, again, I want to draw your attention that this submucosal tissue is pretty loose. It's light pink. Overall, the biopsy is pinker from the actual epithelium to the actual subepithelial tissue. And again, this will make more sense as I progress through the talk and I talk about what I use as a pathologist to make this diagnosis of EOE. So initial evaluation, when I put the slide under the microscope, I want to look at how thick is the epithelium. Is it atrophic? Is it hyperplastic? Different diseases can cause different kinds of effects on how it affects the epithelium. Is there inflammation? And if there is inflammation, what kind is it? Is it eosinophils? Is it lymphocytes? Is it neutrophils? Is it mixed? Is it focused on one area or is it all over the slide? And then can I see any causative agents? So usually what that means is that if there's been any kind of ingestion of a corrosive, some kind of bugs like fungal organisms or some pill that's stuck, usually we can see fragments of that in a biopsy. And then if present, the lamina propria, which is usually the subepithelial tissue that I keep on referring to, if it's present, what does that look like? Is it, you know, light pink? Is there increased inflammation or is it fibrotic? Now coming back to eosinophils and the esophagus, how many are too many and what is normal? And the truth of the matter is, unlike other parts of the GI tract, like I mentioned in the lamina propria, you can sometimes have a few and that's okay, a couple and that's okay. We don't really have any hard and fast guidelines as to what is a normal variation, especially given seasonal variations that you can see in the colon, for example. Further to that, this chart here just highlights all the other reasons, and it's not in any way comprehensive, but some more commonly occurring, like reflux, and some more rare reasons why you can have eosinophils in your esophagus. And you can see they kind of span the gamut here. You have reflux, which is extremely common. You have more autoimmune diseases. You have infectious diseases. So very many reasons why one could have esophageal eosinophilia. The definition here, and again, I think it's been talked about, but what I like about this definition is that it highlights that the EOE is a chronic immune-mediated disease that has two main clinical and histologic features that help in reaching a diagnosis of esophagitis. Again, it's increasing in incidence and prevalence. We've talked about how it's more common in males, more prevalent in Europe and North America rather than Asia, and then more enriched for rural areas and urban areas. Risk factors include factors associated with the mode of birth, prematurity, and then exposures to certain antibiotics early in life. And then as do other allergic conditions, it kind of tracks with having other atopic conditions such as asthma, eczema, or allergic rhinitis. Genetics play a role. We do see this increased in monozygotic twins rather than dizygotic twins and an increase in dizygotic twins compared to siblings that are born at different time points. But in addition to genetics, we also know about the environmental allergens. So just a brief review here is food or antigens passed through an already somewhat impaired or leaky barrier. Those antigens then are presented to the antigen-presenting cell, and that leads to a whole host of inflammatory reactions which recruit not only eosinophils but also mast cells and basophils, and they in turn launch a whole host of reactions. But TGF-beta-associated activation of fibroblasts and myofibroblasts will then lead to deposition of fibrotic tissue, which is directly related to the eventual fibrostenotic complications that we see in chronic EOE. This is the diagnostic criteria, and I won't go over this in too much detail because I'm going to talk about it later, and I know that other people have talked about it. But as you can see here, it includes both clinical and pathologic criteria. Pathologic criteria, of course, is the magic number of 15 or greater eosinophils or 60 eosinophils per millimeter squared, and that infiltration should be isolated to the esophagus. So given all this that I've talked about, how do I actually make a diagnosis? How do pathologists actually make a diagnosis of eosinophilic esophagitis? And again, you'll notice this slide is up of a mucosal biopsy of an esophagus with minimal to no histopathologic changes. Again, I draw your attention to the proliferative compartment, which is the basal area, not more than two to three cells thick. It's just slightly purple, but there's a maturity where you see the cells going towards the top, lose their nuclei, become very pink, and then the lamina propria, again, is not fibrotic, and it contains all the normal elements like lymphatics and submucosal glands and just minimal inflammation. So let's contrast that to a biopsy of a patient with eosinophilic esophagitis. And so in addition to the magic number of 15, eosinophils can actually be present in an EOE patient in many different manifestations. And so you can see here that you see the presence of these eosinophils kind of clustered at the top. These are mini-microapses, and the reason I'm calling them mini is that we're going to see another more robust picture as the talk progresses. But you can also see them individually, kind of percolating through the mucosa. Now, depending on the severity of the disease, these eosinophils can release their granules, and that's kind of highlighted by the areas with the stars where you can see the magenta flecks, if you will, which are the granules that have been released. These are degranulated eosinophils. And what's important to note is when a pathologist is making the final count for the diagnosis of EOE, we do not incorporate degranulated eosinophils, and the common logic of that is, well, how can you account for how many eosinophils it took to release these granules, right? So it doesn't make sense. And so intact eosinophils are counted when it comes to the final number. Again, you can see here that you can see these granules number. Again, you can see here that eosinophils are clustered or present individually percolating through the mucosa or the epithelium here. Another thing I want to point out here, and again, I'm just going to hop right back up to my normal biopsy and come back here and see, and this is what I show my trainees too, which is why you can usually tell, usually I say not always, when you put down a slide of a patient that has EOE, and that's because it's just so blue, right? And that blueness is imparted by the fact that this proliferative compartment, this basal layer, is now sometimes almost three-fourths the length of the actual epithelium. And so we refer to this, as you can see here, as basal hyperplasia. So these cells are proliferating at a very high rate, and they're imparting it because their nuclei are blue, and that's what that stain is stating. So the overall biopsy will have a very blue color to it, and the reason for that is basal cell hyperplasia. So a very characteristic finding of a patient with robust EOE. In addition to that, you can see these eosinophilic cells clustering towards the superficial surface of the epithelium, and sometimes they're also present in the sloughed-off debris that you see up top here. This is called layering, a superficial layering of the eosinophils. It's more common in patients with EOE than other features or other differentials that I'll talk about. So another finding that's helpful. And you can see the sloughed-off epithelium there, and those cells are enmeshed with the epithelium that's being degenerated and sloughed off. And then another finding that is not specific to EOE, but is a common finding, just letting the pathologist know that there is damage going on in this, or there's active insult going on through inflammation in this esophagus. And that is, if you remember, I kept on talking about how squamous, I believe it's the Greek for almost like a fishnet, a very tight scale, like a fish scale. That's what squamous epithelium means. And so any kind of insult, inflammatory insult, will render these cells to have fluid in between them, if you will, and it pushes their cell borders apart. And so you can almost see a white outline amongst these cells separating them, and this is known as spongiosis. It's not, it is a marker of cell damage or epithelial damage or inflammation, and not specific to EOE, but is oftentimes seen with it. So you can see here, it's limited here almost to the basal portion. So we see basal spongiosis, and that's because you see a whole clustering of eosinophils towards the bottom of this screen. Again, just to highlight here what normal looks like, you can see how tightly arranged this non-inflammed esophageal epithelium is. That dark pink outline is how close these cells are to each other, and so when there's active damage, you can see they kind of are spread apart. So spongiosis is also something that we use to make this diagnosis. And then here, before I referred to a mini microabscess, you can see here this is a microabscess, and this is more specific for EOE, mainly because it correlates nicely with what the endoscopist is seeing, and those are these punctate exudates that you can see endoscopically. Now, another feature which we as pathologists love to have, and that is very important, especially when you are making a diagnosis and you want to convey the chronicity that could be relating to what the patient is experiencing, and that is the presence of that lamina propria, that tissue that is right underneath the epithelium. I had mentioned before in my slides of normal esophagus that it's kind of where the submucosal glands are, very sparse inflammation is okay, but in chronic EOE, this is where we assess the fibrosis. And you can see here in both of these tissues that the area underneath the epithelium is showing, it's more highlighted, it's more pink, and that's because there's fibrosis going on here. So if and when this is present, and I think as I go through my biopsies that I show you guys, you'll see it's not always the case, but when we see that, it's important for us as pathologists to convey to the clinicians that there is subepithelial or lamina propria fibrosis. Well, having said all that, easy peasy, right? There shouldn't be any problem in making this diagnosis. Well, I wish that was the case, but there are diagnostic difficulties. And one of the first ones I want to discuss is the presence of the number 15. Now, this is a great number. It's good to have numeric values because it's highly reproducible. If I make this diagnosis and then my colleague across the country makes that same diagnosis on the same patient's biopsy, we have a reproducible objective number that shows high degree of agreement amongst us. However, there are limitations. And so let's go through all of them. The first one, I know Dr. Goncalves discussed a little bit, and that is that there's essentially symptomatic relief or continuity of symptoms does not always track directly with histologic remission. And so it's not uncommon for there to be some kind of a discrepancy or a mild change. If a patient is feeling totally fine, that the biopsies might still show 12 to 15 to 17 eosinophils per high power field on the biopsy review. And again, that's because there is a slight discordance with the tracking of symptom remission to histologic remission. The second problem, if you will, or limitation, this has largely been corrected now, but many, many years ago when we established the number, the count, microscopes of different makers had different fields of vision. And so if you, depending on where you were working or what was going on, this was not something that was well organized in that sense. But this has now been corrected largely because we have limited the high power field to actually a 40x field, which can be calibrated across different microscopes. And for most part, eyepieces are now made in concordance with this. The other limitation is from a pathologist perspective, what is the threshold to define response or cure or treatment, if you will, is that we know it's less than 15, but is it absolutely zero eosinophils? Is it less than 5? Is it less than 10? That's not really clear. Another limitation is the patchy nature of EOE, even within the same sampling. And these two photomicrographs at the top are from the same patient from the same location from the same sample that was taken. And I think you can now agree that one is sure is looks like an EOE biopsy. It's blue. It's got spongiosis that we can appreciate. It's got clusters of eosinophils. And the other one is markedly less exuberant in the damage. And so you can well imagine that if sampling is limited, that also limits the accuracy of the diagnosis. And then as I mentioned a few slides before, a superficial biopsy of just the epithelium is not always an accurate measure of the disease process because if we do not have subepithelial tissue where the majority of the fibrosis can be easily appreciated, you can see in this biopsy, the subepithelial tissue is very dark pink. And this is in keeping with a very fibrotic lamina propria, very, very typical, very in keeping with chronic EOE. If this is not sampled, which is often the case, it's difficult to make that diagnosis. And then lastly, the limitation or the major differential rather when it comes to making a diagnosis of EOE is the more frequent cause of eosinophils in the esophagus, which is reflux esophagitis. So the never-ending debate is always, is it EOE or is it reflux? And as you can see, there are some clinical parameters that can help differentiate EOE from reflux, the patient's age, the way they present, certain endoscopic findings. However, having said that, a very common EOE associated symptom of heartburn can also be experienced in a majority of EOE patients. And then all of these symptoms of EOE and reflux can overlap a lot in children, or they can be totally different. So we have to keep that in mind. I'm going to talk a little bit about the microscopic features that can be helpful. Again, none of these are absolute. They can be helpful. One of the things you'll notice here is that, yes, a slight majority of adults can have eosinophils. But in addition to eosinophil prominent inflammation, in reflux, you can also see neutrophils and other inflammatory cells. But you'll notice here on the bottom that basal cell hyperplasia and spongiosis are common amongst the two. I will just say that basal cell hyperplasia is more robust in patients with EOE. That's why the biopsy seems slightly bluer. Again, the caveat here is very, very exuberant reflux can look like EOE. It's a difficult diagnosis to differentiate. And here I will show this image of a patient with reflux. Again, it's a nice size biopsy because we're seeing some epithelial tissue and some muscular mycosis down here too. But I want to draw attention to the fact that all of the layers are kind of in even proportion. So you don't see a very dark pink or fibrotic lamina propria. And then the epithelium still is not showing basal cell hyperplasia or any major hyperplastic changes, if you will. So they're all in relatively normal proportions. This is another image of a patient with reflux. These are vascular papillae that you see here in the middle. They're kind of where the vessels are and where the lamina invaginates into the epithelium. And one of the findings that we see is in chronic reflux, these vascular papillae can almost reach the top of the epithelium. So this is the lumen right here, and you can see it all the way reaching to the top. So in addition to having chronic damage by eosinophils, you can also see these increase in vascular papillae. The other thing is you'll notice some of these squamous cells seem to have really pale cytoplasm. It's really pale. And the reason for that is the accumulation of certain plasma proteins within the actual epithelium itself imparts this very pale cytoplasm, more commonly seen in reflux than we see in EOE. And then if you see here at higher power, you can see that there's eosinophils in the epithelium. Certainly, certainly they are more than 15 per high power field. But in addition to that, you can also see other inflammatory cells. And those are usually in the form of these dots that we just call them like pale nuclei that you kind of see there. And these are lymphocytes. So in addition to the eosinophils that are prominent, you can see other neutrophils and eosinophils too. All that to say, you know, this is a case of reflux. If you rely strictly on numbers, you run the risk of over or under diagnosing reflux or EOE. So you want to take into account all the other factors that come into play. And again, another thing I want to point out here is that when you have severe reflux, it's important to note that it can look similar to severe EOE. And so, and I'll talk about this towards the end of the talk, but when something is this severe, it's very difficult for the pathologist to be able to make a diagnosis. This, these two photomicrographs, I think, are from two patients whose tissue read the textbook. So you can see that the EOE diagnosis is easier to make. It's very blue. It's got basal cell hyperplasia, definitely more than 15 eosinophils per high power field. Whereas on the other side, you see reflux, it's a pinker biopsy in general. Again, I want to point out that there's more than 15 eosinophils per high power field here also. But if you take into account all the other features, it's more pinker because the basal layer still kind of maintains that four to six cell layer thick, and it's not going all the way to the top. Spongiosis is less pronounced. And so when, when everything aligns, it's easier to make this diagnosis. And then again, this is a chart kind of highlighting all the things that I've talked about how the features overlap, the histologic features, but they tend to be a little bit more robust in eosinophilic esophagitis and mild to moderate in comparison to mild to moderate reflux. But the distinction is always not always clear because the two are not always mutually exclusive. So in addition to the path findings, we also correlate with clinical findings. And this is, I think, where it's very important to be in communication with your pathologist or to provide that in on the requisition form. Or if you are able to talk to someone, that would be great. And that is to let us know if there is anything else going on with the patient. Have they been on medication? Have they been compliant? Has there been any other form of treatment that's been going on? All that is very important to know. And the reason for that is because we like to correlate with what's happening. So these part of our review and helping and differentiate between reflux and EOE is also what is happening over time. So you have two biopsies here. You can see in January, this patient was showing all the robust features of EOE, but the biopsy was kind of superficial, right? Actually very superficial. And then you come to September when the patient is followed up and a harbinger of what the patient is feeling in terms of their fibrostatic complications is present on this biopsy. It's a deeper biopsy and we can actually see the presence of fibrosis. So that correlates. So it's always helpful for the pathologist to go and review what's been going on in the past if it was sampled. Location is always important. There's some overlap, but for the most part, EOE tends to be more robust. Proximally reflux tends to be more towards the junction, the GE junction. And then correlating with again, all the mucosal findings that the endoscopist has seen while scoping is very, very helpful for us too. So rings and furrows are buzzwords that we also use in making our diagnosis. If there's imaging studies, they can be helpful, especially in outlining the thickness or the proportions of the different portions of the wall of the esophagus. And again, these are both robust examples of patients that have very severe EOE and reflux. And you can tell, unlike the other photomicrographs comparison that I showed, I can't tell what the difference is here. And sometimes what's really needed at that point is to convey in our report, the degree of inflammation, the severity, the ESNF count, and the tincture of time and treatment. And then re-biopsying is really what will help elucidate if this is EOE or reflux. And so I'll end my talk here just with some pearls about numbers are a great part of the criteria, but not the only defining feature of disease. It's important for us to be aware of all the features that are present and absent, clinical or pathological, and correlating with these. And again, because of the patchy nature of the disease, as Dr. Gonsalves talked, the more biopsies you have, the more diagnostic accuracy you can expect from the pathology. And of course, comparing with any kind of prior pathology samples, if you don't have a sample, even being able to review a report would be very helpful. So with that, I'm happy to take any questions. I will stop sharing my screen. I have a question, and thank you so much, Dr. Salaria. That was really insightful. My question is, so in parts of our regions, obviously, we work with a lot of community practices, and I have some surgery centers that are sending specimens to LabCorp, for example, where they're looking at all different types of specimens, not just GI-specific. Do you feel that this could easily go undiagnosed in those situations, or do you think that overall, EOE is not super-difficult to diagnose? That's a great question. And I have to say, that's where the more information on the requisition, the better. Now, if there is robust information, like the examples that I showed, where there's clustering, there's all that other stuff, that's where you're going to have If there is robust information, like the examples that I showed, where there's clustering, there's all that other stuff going on, this is standard of care to be documented and reported in the actual pathology report. The issue, I think, becomes when patients maybe have been treated, or if it's earlier on in the disease, and the pathologist is not aware, and they just see, it's not uncommon to see esophageal biopsy, or esophagus biopsy, and proximal and distal are not listed, and why the biopsy is being done is not listed. I don't think it's a diagnostic difficulty, but I think when information is limited, the pathologist is limited by how they can correlate with the clinical information. Awesome. That's very helpful to know. Thank you. Okay, so that was my question, so whoever it was that asked that, thank you very much. But a second one, maybe this will work with you. In EOE, we know Eos love to live in the furrows, but when a patient has scar tissue, do Eosinophils live in the scar tissue, or do you almost need to take a bite of the scar tissue to get to that deeper layer to see the Eosinophils in that subepithelial layer? So Eosinophils can percolate through the epithelium into the lamina propria, or where the scar tissue happens. It's not limited to the mucosa itself, it's just that that is the most common sample that we would get. Usually, resections are not done for Eosinophilic esophagitis, but if they were, it's not uncommon to see Eosinophils percolating through into the lamina propria, and in fact that's how they can elicit that damage there when it's chronically done. Now, you don't need to have the magic number of 15 in the lamina propria if you're seeing fibrosis. If I am seeing the adequate number of Eosinophils plus all the other features that I talked about up in the surface, and then I have lamina propria or scar tissue, that's enough. I don't need to see Eosinophils in the scar tissue to correlate that to what's happening in the patient. They're all part and parcel of the same pathologic phenomenon. Great, thank you. Dr. Salaria, this is Diana Snyder. I do have one question, and it may also, you know, help the audience to understand since this is used more in clinical trials. Can you talk a little bit about the EOE histologic scoring system, and how, you know, that's something at Mayo we are reporting clinically? It often confuses my patients, though, since we're not really using it clinically. It's more in the trials, but can you talk to us a little bit about that to educate us on what that means when, especially when we see it in studies? Yeah, so I will say first and foremost that, are you seeing it at the Mayo in your routine biopsies? Yeah, our pathologist reported for every EOE patient, but we're not really using it clinically, but more just for research. Right, and so that scoring system goes through a whole host of many of the features that I've already talked about with the eosinophil counts, all the other features that are not necessarily specific to EOE, but are part and parcel of making that diagnosis. So the degree of fibrosis, the number of eosinophils, whether micro abscesses are formed, and all these are clustered to form a part of the diagnosis in that score, I will say it is extremely time consuming for the pathologist and for larger centers where you are seeing, I mean, sometimes hundreds of these biopsies a day with multiple parts. It's not clinically feasible to be doing this on every, sorry, my camera isn't acting up, on every single biopsy. It's more for research purposes. And I, everywhere that I have worked thus far, we have only used, utilized that in the practice of when it's suitable for some kind of clinical trial, or if we're re-reviewing it. But for daily practice, the presence of eosinophils, the number, whether you're seeing micro abscesses and the presence of fibrosis are the standard of care currently. But that score largely, again, it goes through different histologic parameters to, to impart the patient into different categories of severity of EOE, as I mentioned before. But I, our gastroenterologists have not asked for that. And like I said, it's a extremely time consuming practice. Thank you. Any other questions from the audience? So mine is really a clarifying question. When diagnosing EOE, two of the criteria is, it has to be over 15 eosinophils, and it also has to be isolated to the, to the esophagus. How do you know, because we learned how to do biopsies yesterday, how do you know it's isolated to the esophagus when you're only taking it from the esophagus? Oh, I guess that part of that criteria is that, for example, you don't have some kind of a eosinophilic gastroenterocolitis. So there are times when the esophagus is, when someone is doing an upper endoscopy and they biopsy the esophagus, the stomach, the intestine or the colon, and there is a uniformity, an increase in eosinophils. That might be part of a more generalized systemic process. And so if I, you know, if I'm, if usually in patients, unless they're just strictly EOE, it's not uncommon for a pathologist to receive a proximal and distal esophagus, you know, GE junction, stomach fundus, stomach antrum, and then small intestine. And so in that patient part that has four or five biopsies that were done, it should be limited to the esophagus, the esinophil proliferation that you're seeing. Yeah, that makes sense to us from the endoscopic side too. So when I see patients in clinic that have symptoms of EOE, I also ask them about abdominal pain, nausea, vomiting, weight changes, diarrhea, other symptoms to see if there's a clue that there could be other processes like EGIDS going on. The prevalence of those, as you all know, is much less common than EOE. But we do target and biopsy accordingly based on symptoms. Because the other issue with EGIDS is often endoscopically, the stomach or small bowel appear normal. So I biopsy often based on symptoms, because you may not have features like we see with EOE. And Dr. Gonsalves might want to comment on that more because she's the EGIDS expert. Thanks, Dr. Snyder. That was actually a great question. And Dr. Solaria, sorry, I'm not there in person to talk to you, but nice to see you on Zoom. So that's a really important question. And there are studies that have been done, and we've done it at Northwestern, others have done it as well, in terms of looking at the prevalence of gastric eosinophilia in patients with EOE. And there was a period where we were biopsying everyone in their stomach and small intestine, everyone who had EOE and had less than 5% of those patients actually having significant gastric eosinophilia. So I completely agree with Dr. Snyder in that, you know, the only time that you should really be thinking about biopsying that stomach and small intestine is in a patient who has those characteristic symptoms and or has those endoscopic features. That's going to be really important. And so understanding what those endoscopic features are will clue that endoscopist into taking those biopsies. I have one more question, and sorry to be annoying, but, and this is more, I guess, in practice in the endosuite. What techniques are you guys using to ensure you do get the subepithelial layer and not just like a superficial biopsy? Yeah. So, I mean, that's a really good question and something that we try to train all our fellows. And basically they're, you know, as you know, like that esophagus can be very stiff, right? And sometimes, especially if it's a narrow caliber esophagus, it could be hard to kind of get those bites. So there are specific type of techniques where you can open up the forceps, kind of put it in directed towards the wall of the esophagus, kind of suck in that mucosa to kind of decompress that esophagus and then kind of grab that tissue and take that bite. Sometimes if you want to try and get deeper to that lamina propria, you can do what we call bite on bite biopsies. We typically don't use large capacity forceps in the esophagus. I don't think you need that for EOE, but doing the bite by bite can give you deeper tissue and doing that proper biopsy technique. The other thing that we do, and Dr. Solari, you mentioned this about that really good communication with a pathologist, that's critical, is there's also a piece where you have to have really good communication with your technician or your nurse. So every jar that I do, I ask the nurse, like, do we have four good pieces in there for that distal esophagus? If they do, then we move on to that proximal esophagus. If we don't, then we take more tissue. Because there have been studies that have been done, I believe, at Utah that suggest that there is a lot of disconnect between taking biopsies and what actually ends up in the jar. So you might be taking five passes, but you may not get only one piece in the jar. It gets lost in the channel. It gets lost elsewhere. So you really have to have that critical communication. And I harp on that with our fellows to say, make sure the nurse has the tissue. That's the most important thing we do as endoscopists. We have this patient. We're getting the tissue. We need to give good enough tissue to the pathologist. But then in all our EOE patients or EGIT patients, we have a note to the pathologist that says, this is our key diagnosis. Please look for this. Please count the ESNFOs. This is what I'm thinking. And so I think that's critical, especially as you mentioned in some of these other path centers where you may not get that information. Thank you. I think it's also important to note when you're in there, again, I don't scope, but depending on how severe the mucosal changes are, the correlation also, again, why it's important to have a lot more samples is that sometimes you may think, oh, I got a really big, good chunk of something. But it might be a very superficial portion of just like that big ESNFO like micro abscess. And so I have very limited tissue other than the inflammatory component, right? Depending on how exuberant the mucosal changes are. So the more that you are provided as a pathologist, the more you can interpret. I think that's all the questions that we have for now. Thank you so much, Dr. Salaria, for an excellent talk. My pleasure. We appreciate it. Thank you.

Eosinophilic Esophagitis

Gastrointestinal Pathologist

Biopsy

Eosinophil Count

Microscopic Features

Reflux Esophagitis

Histologic Scoring

Clinical Correlation