Hello everybody, and welcome to today's webinar with the webinar vet. My name's Catherine Bell and I'm delighted to be your chair for this session, which has very kindly been sponsored by Nationwide Laboratories. Before we begin, just a couple of quick housekeeping notes please.
So we are really pleased, that today's presentation with Sandra is being delivered live, which means you'll have the chance to put your questions directly to her in the Q&A session at the end. So if anything comes to mind as you're listening, please just pop your question into the Q&A box, and I will do my best to put it to her later. As always, for those of you who might be wondering, your certificates will be available once this session has been uploaded to the webinar vets platform, which we aim to do within 48 hours.
OK, so back to our session today. So as you can see, I am very pleased to be joined by Sandra Dawson. So for those of you who may not know Sandra, I'll tell you a little bit about her and then I will pass over to her for her presentation.
So Sandra graduated from Aberdeen and Glasgow Universities, earning her degree in veterinary medicine after completing a Bachelor's of Science in agriculture with honours in Animal Science. She began her career in mixed practise before moving into veterinary pathology, undertaking a residency at the University of Edinburgh, where she later lectured in reproductive pathology. After several years in industry, during which she gained her fellowship of the Royal College of Pathologists, Sandra joined Nationwide Laboratories in 2006.
She was appointed to the Royal College's Board of Examiners in 2011, specialising in small domestic animals. Sandra is passionate about teaching and mentoring and is also an active STEM ambassador. Her work today focuses on surgical biopsies and fine needle aspirates, and she provides expert advice on all aspects of histopathology across a wide range of species.
So welcome Sandra, thank you so much for joining us live today. A big thank you again to Nationwide Laboratories for very kindly sponsoring this session, and I will pass over to you now. Thank you very much.
Thank you, Catherine. Thank you for that lovely introduction. Good afternoon everybody.
My name is Sandra Dawson and as Catherine says, I am an anatomical pathologist working for Nationwide Laboratories. If you've been quite astute in listening to that introduction, you will realise I've been working for Nationwide now for nearly 20 years. My main focus is on surgical biopsies and looking at histopathology, but in recent years I've also been reporting cytology, and I've become very curious about how we correlate histology and cytology specimens.
And those of you in practise who perhaps look at your own histology, or maybe you look at some of our pathology reports and despair over not being able to correlate between histocyto, join the club, I've been quite curious about looking at our histology reports. And looking at my biopsy reports and making sure that, we're, we're all along the right lines. And sometimes you may have seen some of these cytology reports which say, inadequate sample or non-specific findings or not enough, .
It maybe doesn't correlate, and you think to yourself, well, was, was that a waste of time? Was there anything worthwhile in that? And even in some of those reports, we can perhaps draw out some clues as to what might be going on, particularly once we have a look at the histology.
So I hope to have a look at that this afternoon. We're going to start by seeing how histology and cytology fit into the, the reporting procedure and what those reports can give to you. We'll try and navigate around our reports a little bit.
We'll then look at the, the importance of being able to correlate and what happens when we get a discordance. In our results, and during that time, I'm going to have a bit of audience participation, so if you have a scrap of paper and a writing implement next to you, bring that to you now and we'll use those later, you'll see why. Once we've had a look at why we might get some discordances, I've then got some interesting cases to show you to hopefully highlight that.
And then we'll finish up by having a look at what we can maybe do to use this correlation as a quality control measure, both for when you're looking at your own diagnostic laboratory that you send to, and also within practise if you're taking and reading your own cytology specimens, how do they correlate? With the histology reports that you get back, and how can we record that to give ourselves more confidence that we're doing the right thing. So that should take us through till about 1:30, I hope it does.
And I'm available to answer any questions at the end. So let's get started. As you can see here, this is where cytology fits into a sort of linear diagram.
Our cytology is reported by both clinical and anatomic pathologists. And if you wondered what the dividing line was between us, our wonderful clinical pathologists are very, very good at sample analysis and looking at the figures of that, of haematology and fluids and things like that, which we anatomical pathologists don't look at. The anatomic pathologists tend to look at the structure of tissues.
But we're both trained to read cytology, and we both input into the, the, the production of the cytology report. The cytology report is an interpretation, in my mind it is anyway. There are a few cytology reports that will come out with a definitive diagnosis, but mostly it's an interpretation.
What are we going to do from here? What will we do next? At the same time as our interpretation, we're correlating it with the clinical history, and yes, we do look at clinical history, and it is important.
We will correlate that with clinical history and any other tests that you might be doing around the same time. So we're keen to see imaging, culture and sensitivity, all of that kind of thing, and that feeds back into our interpretation. So if we have that little triangle there and we have all this information.
That can make our interpretation much more accurate and wide ranging than we might otherwise have. Once we have this interpretive report, we could. Advise repeat cytology.
Or some special stains, immunocytochemistry or para analysis, that might be a way forward, or we may suggest that we go to surgical biopsy with histological evaluation, and that's important for particularly grading of tumours, looking at margins, looking at extent of infiltration, and we may from there suggest further tests. And I'm sure you're all aware of this, this, this slide here, what the benefits and limitations of cytology are. We know it's rapid.
It can be done fairly quickly, usually without any anaesthetic, so it can be done without booking the animal perhaps back in to see us again. It's quite cost effective, because there's not all the the anaesthesia and paraphernalia of surgery around it. And it can give us a very quick guide if we're planning to take this lesion or mass off just for our future surgery.
So, how, how big are we gonna have to make this wound, or can we just, shell this lesion out and, and it'll be OK? It's also important for our elderly patients and patients with comorbidities that we might be having a second thought about doing an anaesthetic. So if we have an elderly animal that comes in with a fatty lump that we're confident is going to be a lipoma, we just want to take some cells off of it and confirm that.
That tells us we've got a lipoma and we don't need to worry, we can monitor that, that lesion rather than worrying about going in and doing surgery. It's not just the fine needle aspirates for cytology, we can also take some quick impression smears from the surface of ulcerated lesions and things like that. So it's quite a ubiquitous and and flexible way of gaining more information about a lesion.
I'm sure we're all aware of the limitations. We've got an extremely small sample size. We can't see tissue architecture and so we're not sure if what we've got is representative of the lesion.
There may be underlying lesions that we're not aware of, and it's very rare that we could grade any neoplastic lesions just by looking at cytology alone, and I'll come back to that. So for those of you who do your own cytology in practise, you may be familiar with this sort of cytology. This was taken from a microscope.
This isn't a digital image, and I like this image because we can see some lipid here and we can see these really big foamy adipocytes that we've aspirated from a lipoma. And this is quite satisfying. We've got a discrete nodular mass in an animal.
We can see these adipocytes in this lipid. We're fairly confident we've got a lipoma, and this means we've got time to monitor this lesion, and it, and we can plan our surgery for other lesions. So for example, if this gets so big or it becomes traumatised, obviously it'll need surgery, but it's not something we need to rush into right away.
And if you want to see a digital image, you don't get the lipid on the digital image, but you get these lovely big balloon shaped aggregated cells that tells you that you've aspirated fatty tissue. At the other end of the spectrum, if we aspirate these, granular cells with a lot of this granular activity in the background, that tells us that we're, aspirating a, a mast cell tumour. And, and so that means we're gonna have to do a bit more planning for surgery.
We're thinking about grading this mast cell tumour. We might want to know how infiltrative it is. We might want to know if it's quite superficial or deep down.
So we're going to be planning other things for this lesion. So these are very quick, cheap and cheerful ways of giving us much more information about a lesion, than we might otherwise expect. Unfortunately, not all of our cytology looks like that.
Quite a lot of our cytology looks like this. These are hypercellular and acellular samples where we have very little cellular activity to go on. We've got some fluid, we've got some debris in the background, but there's very little in these samples to tell us what we've got.
If we're, if we think we might have a cystic lesion, then perhaps we think we've aspirated some central cystic fluid. But we don't know whether that lesion's lined by epithelium or whether it's a seroma or, or what we might be dealing with. And sadly, a lot of our samples do look a bit like this, which is why you finish up with a non-diagnostic report.
So how does the report fit into the, the procedure and how do we navigate round our report? So, I've popped on here on the left-hand side, a cytopathology report from one of my clinical, colleagues. And, I've got some information at the top there.
This is what our report will look like. So we know that this sample is from a 1 year 8 month female miniature. Schnauzer and the first part of the cytology report identifies, our, our patient so that when you look at your report, you're happy that you have got that patient.
The next part of the report talks about the samples we've received, how many slides we've received. Now you might have sent fluid or you might have sent other things. So it's important to look at that report and be comfortable that that's what you have sent us and we've received.
And we always have a bit of description about where, the location of this sample, we might have a bit of additional information about its rough size, we might have some information about how it feels, what its texture is. Then our cytopathologist will tell us a description of what they see when they look at this sample, and we know here that one smear didn't have any cells on it at all, but two other smears did have some cells, they had, some fat vacuoles, they had some macrophages, and these were arranged around the fat vacuoles, and that they were moderately activated with foamy cytoplasm, and we had some multinucleate cells there. So that's quite important, and in the body of this report, the cytopathologist may also tell you whether they saw any debris in the background, any infectious organisms, and whether any of these cells looked atypical that might suggest we've got a neoplastic lesion going on.
In this case, it didn't. And they were comfortable that this was an inflammatory lesion, and in conjunction with the lipid that they saw, they wondered whether this might be a paniculitis or steatitis. And then the final part of this report is always a comment, and maybe explaining why they've come to the decision that they've come to.
And they may suggest some possible causes, and they should suggest something about what to do next. And they've said please correlate with the clinical history of the mass. And the reason for that is if, if this is what it is, it might be something that the clinician doesn't want to remove.
They might just want to monitor it, but if they felt that this was something that needed to be looked at surgically, then they'd say that in the report. So a week or so later, I did receive a, a sample from this animal, and this is an example of my histology report, and you'll see that the wording is slightly different from the histopathologist. So, I talk about the macroscopic, findings that we had.
So, clinically this animal did have, multiple subcutaneous masses, and I do acknowledge that we have a, a, a cytology. I always look back on our cytology reports so I can correlate them. And I describe what we received in the laboratory, and that's always very useful to look at to reassure yourself that what you've sent is what we've received.
Then the microscopic is a bit like the description, and I will describe what I see down the microscope, and I will then add into this architecture to this lesion. So I will see her skin overlying and I can locate where this lesion is. It's in the subcutis, extends into deeper muscle.
We've got inflammation, we've got fibroplasia, we've got macrophages that we noted in the, in the cytology report. There was some necrosis and a bit of haemorrhage at the middle of the adipose tissue, and then I described how far, how the lesion extends, it doesn't go into the haired skin, and it does go to the lateral margins of each section. As a histopathologist, I tend to come out with a diagnosis rather than an interpretation, and I do this whenever at all possible, and it is consistent with a fibrosing paniculitis, just as our clinical pathologist said.
I will make a comment as to how this might have arisen, how I would expect it to behave, pathologically, and whether I think that surgical excision is enough for excision or whether that, that you, you might need to do something else. So that would be how to very briefly navigate round your your pathology reports. Moving on to actual correlation and what we can do with this correlation, is there any evidence out there in scientific publications regarding correlations?
This is a very good report. It's quite an old report now. It's from 2008, and it's come from Italy, but it talks about the correlation between fine needle aspirate cytology and histopathology, and it looked at the evaluation of cutaneous and subcutaneous masses from dogs and cats.
Now I have to say this afternoon, I'm largely going to, to concentrate on this, it's a huge topic, but a lot of the principles that we talk about today could be applied to all species, all locations, fine needle, ultrasound guided fine needle aspirates, aspirates from surgical specimens and things like that, will all be quite similar. But I'm gonna concentrate today mainly on the really common cutaneous and subcutaneous lesions that we see. This paper looked at nearly 300 cases.
It looked, overall, the cytological diagnosis was in agreement with histological diagnosis, about 90% of cases, which is pretty good. And specifically for neoplasia, just below 90% of cases. What I would say is that from this paper, 49 cases were excluded from the study due to poor cellularity of the specimen.
And that interested me because in a first opinion pathology practise like I am in, we see quite a lot of these poor cellularity cases, so that would skew my results. The other thing I noted was that they didn't include mammary masses in this study. Now we look at quite a lot of cytology from mammary masses, and it is really difficult to correlate.
There are several reasons for this. I've got a mammary case later on, so we'll talk about it then, but they were excluded from this study. So again, if you did your own percentages and you included all the poor cellularity specimens and all the mammary masses, you might find that your accuracy was considerably lower than 90%.
This is a more up to-date paper from Vets Science, and it talked about, correlating cytology with histology from neoplastic and non-neoplastic oral cavity lesions in dogs and cats, and again, it looked at over 100 cases. It's a retrospective study of over 12 years, and it, it was both neoplastic and non-neoplastic, and it, it came up with an accuracy of about 87%. Specifically for neoplastic lesions where cytology positively correlated with histology, it was very, very good indeed, about 96%.
It's sensitivity, so that's negatively saying that something's not there correlating, it was a bit lower. And again, you'll note that about 25% of samples were excluded from the, the trial because of scarce or absent cellularity, blood contamination. And other things like exposure to formalin fumes.
And again, I would say that in, in a first opinion pathology practise like ours, we will see a lot of cases like that, and we will have to do a report on them. And finally, with the papers, I was interested to look at this. This is a human paper on gynaecological cytology, but also with correlating histology.
And this has come out of the states, and in the states, they try to have, quality assurance methods of correlating the histo and, and, and, cyto . Cases, you'll notice that in human, pathology, they tend to split into groups, usually regarding body systems. There's not an overarching thing, and this was from the, the gynaecological people.
And the reason I've included this study is because our next slide, they've come up with a, a very good list of the causes of historic cyto discordant in cases, and they correlate very well with what we find at nationwide laboratories. Overwhelmingly, the biggest problem is sampling issues. So we don't have, as I said before, enough tissue, the sample scan, it's not representative.
Secondly, there is the old chestnut of an inadequate or inappropriate history. From the cytologist and histologist's point of view, our errors can involve slide screening, and that is where we just simply don't see the diagnostic cells on the, on the, the, the slide. Or secondly, we see them, but we don't interpret them as being significant.
And again I'll show you an example of that. We may have some processing or preparation artefacts in our samples that hinder interpretation. And from a histology point of view, we don't get off lightly, even though we can see more tissue, we may require additional levels of processing or reorientation of the specimen to actually find the lesion that the needle picked up.
So all of these are important. So why is this the case? Well, if we look at this pictorial representation, this is my daughter's Disney princess, a jigsaw puzzle.
My daughter is now 15 and doing GCSEs, so she will not be impressed that I've got this, but never mind. If we look at the whole picture of these Disney princesses, we can see what that image means, we can imitate it, we can interpret it, it causes, . Relationships in the back of our head that we know what it is and what it refers to.
And if you imagine that that is your lesion that you're looking at on your animal, it might be a neoplasm, it might be an abscess or something like that, but you have the whole picture of that lesion in your mind. You can see the size of it. You can see whether it's been excised.
You can see what cells are in it. If we look at the graphics on the right of the screen. And we've got these few pieces of jigsaw puzzle.
We can see here that at the bottom, we may only have a couple of cells on our slide as these two pieces of jigsaw puzzle, and they, we really can't correlate them back to the main lesion. They don't tell us anything very much at all. If we're lucky and we get a well exfoliated sample such as this one here, we might see a face here of a princess, we might have a little bit of a frock or something.
Then we can start to get an idea of what's going on and that might give us some clue as to our interpretation. The two graphics here, these represent a punch biopsy or a needle core biopsy for histology. And again, if you look at this sample on the right, you can see what we've got here is the very edge of the lesion.
And it doesn't tell us a huge huge amount. We've got a bit of structure, but we don't really know what's going on. If we're fortunate to get a core biopsy right through the centre of the lesion, then we've got a pretty good picture of what, what might be going on and, and, and at this stage, the histology becomes a real advantage to the cytology.
At the top here, this is why most anatomic pathologists will tell you we like a nice big wedge biopsy of a lesion, and you can see here why we need that. We've got pretty much the full idea of what's going on, and the only difference between this incisional biopsy and the full lesion is we can't see the borders. That's the only difference.
So if we change that to an actual specimen like we have here, this is a benign mixed mammary tumour. It's a histological preparation of a benign mixed mammary tumour, which is really common in the bitch. If we imagine inserting our needle into this side of the lesion here, we will get some cells that exfoliate quite well for cytology.
These branching tubules and clefts here are bordered by neoplastic epithelial cells, and we will see these quite clearly on our specimen. If we're lucky, we may exfoliate some of these paler areas here, which contain spindle and steella myoepithelial cells. These are the epithelial cells that normally border the basement membrane, and when they contract, they squeeze the ducts into the into the bigger ducts and, and to help to produce the, the milk out.
So, but these are proliferating haphazardly here, so we may get some of these cells. I hope you can see that if you exfoliate from this area here, where we, quite commonly will see bone or cartilage in mixed mammary tumours, this structure here does not exfoliate well at all for cytology. We may get an acellular sample if we, take an aspirate from here.
And equally from the centre here where there's a lot of collagen, collagen is quite acellular. It doesn't exfoliate well for cytology, and we may get. A poor sample from this lesion.
And as an example here, I have a case of, an 11 year old entire female shih-tzu called Mia, and we received an aspirate from her mammary mass. And, if you look at the, the smear on, on the, the left here, you can see these tight clusters of sort of angular or cuboidal epithelial cells. You can also perhaps see these more elongated nuclei with more fibrillar cytoplasm on the outside here.
You've Got a background of fluid with some blood and some lipid facules, which is quite understandable because mammy tissue always sits in the fatty connective tissue of the subcutis, and we've also got some matrix here which I see quite commonly with the spindle cells. So in this we've had some epithelial cells, we have some spindle cells, and just as an aside, as we moved around this lesion, we also saw some clusters of quite atypical cells that might suggest to you that this neoplasm might be malignant. And, these are way different from these cells.
They're different in size and shape, they're bloated, they've got big nuclei. So you start to be concerned that there might be some, aggressive behaviour here. We've still got our spindle cells.
We've also picked up some macrophages. And just to add, complication to the whole picture, we've got a cluster of sebaceous cells down here. So why might we have that, that sort of picture?
Well, if you look at the histology that was sent to us, you can indeed see this is what a mammary tumour looks like. We have some inactive mammary ducts here, and I'll just say at this point, it is really helpful for the pathologist to know the estrus, stage if you've got an. Entire female, it's really helpful to know because then we can, that can also correlate into what we see.
I find, bits, that are any stress at the time you take a cytology, the cells can look a little bit more aggressive than you would otherwise think. So we have this well, well demarcated but irregular tumour. It's got some necrosis in the centre, and if we concentrate on this red squared area here and we look at the infographic here, this is magnified to about 400 times.
You can see why we picked up our clusters of epithelial cells. We've got these tubules lined by these cells here. You can see why we've picked up a cluster of quite atypical cells because they've exfoliated off into the centre of the tubule and then they've expanded.
They're not actually truly malignant, but they do appear malignant on a cytology specimen. These are our myoepithelial cells, our spindle cells loosely aggregated within the stroma, and then in one dilated duct, we've picked up some macrophages. Here, they've come in to try and clear up any debris that, that is in this tumour.
And if you think about taking an aspirate through this tumour here, if you were to continue suction. As you withdrew this aspirate, you could very well pick up some follicular adnexal tissue as well as you come up through this lesion. Just another, quick thing to say about sampling issues, .
Down here on the bottom left, we've got a nice aspirate from a lymph node with a mixed population of small lymphocytes, some debris in the background, some large immature cells, and that fits really nicely with a very happy lymph node here on the right. If you take an aspirate from a submandibular mass expecting lymphoid tissue and you see this, which is clusters of epithelial cells, quite foamy epithelial cells in the streaming stroma, even the, even the red blood cells are forming rows here, you know you've gone to the wrong place, you know you've sampled salivary gland, which is what we can see on the right here. And that does happen, fairly commonly.
So what about our sampling issues? In this infographic here we have quite a poor cell yield, and these cells are very squashed and disrupted. They're not easy to see.
We've got this very granular background and we've got an impression that these cells have got granules with them. Already we're suspicious we've got a mast cell tumour, but it's not classic. We did get a a a a piece of tissue.
We got an incisional biopsy from this lesion. Unfortunately it was quite compressed and very hemorrhagic, and that's quite common following cytology. Cause a bit of haemorrhage in that tissue and you start to cause the mast cells to degranulate.
And if we look on the high power again. We can see these sort of relatively uniform cells in this haemorrhage, but they're not, it's not easy to see the granules, and a lot of these cells are actually hemosiderophages, but I'm just a bit suspicious as to what some of these other cells are. So what I would do here is add a mast cell stain onto this, which, in this case it's toy in blue.
This stains up the mast cells very dark purple colour, and I, and because they're clustered. This adds to my evidence that we're dealing with a mast cell tumour here, so there are some things we can do with sampling issues to try and get more information. Just briefly on here, this is just to show you that there are various techniques of, taking your cytology specimens to try and help with that good quality smear.
We can take, scrapes or impression smears. Mostly we take fine needle aspirates, particularly if you've got a solid mass, and we can do that with suction. Or without suction, and without suction, that just means inserting the needle, allowing capillary action to pull the cells into the needle hub, removing the needle, then adding the syringe, and then you gently squeeze a bit of air in through the needle to push the, the material onto the slide.
We can also use touch preparations, and that's quite useful if you're doing surgery and you have an internal mass which you've removed. If you slice that mass and do a few touch preparations before you put the mass in to fix it, you can get a fairly rapid picture of what's going on. I would suggest you take multiple aspirates from different areas of the lesion or different lesions, and you can reorientate your needle within the lesion to try and get as as wide .
A group of cells as you can. And on the left there we have the spread technique like you would for a haematology smear, or if you've got very thick tissue on the side, it's quite useful to do a gentle squash preparation where you lay the slide over the top and move the two slides apart. So an inadequate or inappropriate clinical history, and here's the point where I'd like you to get your piece of paper and a pen.
Very quickly, I'm gonna ask you to draw a circle. And then I'm going to ask you to draw another circle. Outside your small first circle.
Once you've done that, I want you to draw an arch or a curve over the top of your outer circle. Following on from that, if you draw another. Upside down arch or curve under your, under your circle, under your outer circle, so that the two lines meet.
And then finally, I want you to draw 6 radiating straight lines from your upper arch. Now if you think that's a bit complicated and you've heard it over it only once, don't worry, give it a try and have a look at the diagram you've done and we'll have a chat about this in a minute. So inadequate or inappropriate clinical history.
As you can see here, we've got a diagram here just with a cross in the middle, and sometimes that's the only history we have. I don't know whether that cross means a skin lesion, subcutaneous mass, or possibly sampling from the abdomen or thorax. I've no idea.
But that's something that we see quite a lot. Sometimes we get more than one cross and a very brief clinical history, find needles for inconclusive possible lymphoma. Now there's a little bit of a red flag in this history, for this histology, in that I don't quite correlate these locations with lymph nodes, so I'm immediately suspicious.
When I do look at the histology. I find actually, the clinician's not worried about lymphoma, they're worried about lipomas. And that's a whole different ballgame and report to write.
So that's just a, a little bit of, of an alert to make sure you provide a good clinical history and that you're aware of all your terms, your anatomical terms and your, your pathological terms so that you're communicating that history correctly to the pathologist. At the very least, what I'm interested in is what made that patient walk through your door today. Why did that patient come to you?
Can you see that lesion as soon as the animal walks through the door, or is it hidden? Or was that lesion only found because the animal came for a checkup? Moving back to the diagram that I showed that I'd asked you to describe, I wonder how many of you knew that what I was asking you to draw was an eye.
I'd be very interested to know. The whole point of that is to show you that communication can sometimes be quite confusing, and what I know in my head I want you to draw may not come out the same way as what you receive from me. If I told you to draw an eye, it might have been so much easier.
Moving on now to another problem with the cytohito correlates, and that is where diagnostic cells are not detected. And for this I want to introduce you to Bella, who's a Maine Coon cat, and she was presented for a mass in her left axilla. We had a look at some cytology specimens from a fine needle aspirate from this, and our cytologist reported out that they could see a lot of debris in the background, but also some quite prominent eosinophils and a lot of lymphocytes.
And knowing from our history that this mass is in the left axilla, she spoke about eosinophilic inflammation, but she also wondered if we had an eosinophilic lymphadenitis in this case, and that was her interpretation. And indeed if we look at the histology, this is a bisected specimen from this animal, we can in fact see lymph node here with a very reactive connective tissue extending into the muscle round the outside. And indeed on high power we can see lots of eosinophils in this tissue.
And also some lymphocytes. We do in fact have an eosinophilic lymphadenitis, just as the cytologist thought. However, me being the histopathologist, I was curious in this reactive tissue around the outside.
So moving away from the lymph node, I looked at this tissue around the outside and thought this is really unusual, and this is not normal reactive connective tissue. And indeed on high power it's not. This is a neoplasm.
This is a lymphangiosarcoma, and these are endothelial cells lining vascular spaces. There are very few erythrocytes in here, so it's not quite a hemangiosarcoma, but it is a vascular neoplasm. And this is a feline, lymphangiosarcoma.
It might also be known as a, a ventral abdominal wall sarcoma. You might see it recorded as this. These cells do not exfoliate well for cytology, so I'm not surprised we didn't pick this up on cytology.
I have 2 cases here where the Specific cells are on the smears, but I just didn't interpret them correctly. So I have a case of a 2 year old golden retriever with an aspirate from a mass on her abdomen. And I hope you can see in this specimen here that we have some very big, very unusual spindle cells for this dog.
And I would interpret these as a proliferative mesenchymal lesion. I'm concerned that she may have a mesenchymal neoplasm, but I couldn't rule out that these are immature reactive spindle cells. Interestingly, at the same time, I received a very similar cytology from a 13 year old golden retriever from a mass on her neck, and again, what I saw were really big, plump, unusual looking spindle cells.
And this dog got a very similar report. I was suspicious that there might be a spindle cell neoplasm, but I couldn't rule out an immature reactive tissue. The histology from the younger dog showed a well demarcated fatty nodule with lots of fibrous connective tissue through it, and on high power this turned out to be a reactive fibrosing paniculitis, such as you get with a localised blunt blunt trauma.
Unfortunately for the older dog, she showed a much different lesion. She showed a very infiltrative, highly cellular, pleomorphic spindle cell neoplasm, soft tissue sarcoma, and in this here, you can even see mitotic figures. So for that, and these two cases, although they showed similar cytology, the histology was very different.
For those who are interested, there is a paper from, the University of Cambridge which tried to correlate grades of soft tissue sarcomas in dogs. They did a pilot study where they looked at psychological features and then looked at the histology. They only saw a very weakly positive correlation with the number of mitotic figures and high-grade tumours.
So it, it wasn't a very specific or sensitive correlation, and you do still need histology to work these, these tumours out. Moving on to processing artefacts, here we can see the effect of formalin fumes on the right here, so these cells, have been exposed to formalin fumes in transit. Formalin fumes fix the outside of the cell, so that means that the stain can't penetrate to the nucleus and you can't see the fine detail of these cells.
So this makes the, the sample useless for analysis. The difference with this specimen is this specimen was fixed, but the, the, this specimen, sorry, was stained, with a benchtop stain. It wasn't very well stained, so what we did in the lab, these cells are not fixed, so we were able to decolorize and re-stain to get a much better differentiation of these cells.
Just to make you aware, some tumours, you can, get one tumour underneath another tumour, and if you only take, a superficial fining glass bit or even a superficial surgical section, you will only get one tumour, so you will only see this benign vascular tumour and not know that there's a mast cell tumour underneath. Equally, you may get a mast cell tumour on top with a lipoma underneath, and if you send that needle straight through that mast cell tumour and you do a really good aspirate, and you don't aspirate on the way out, you may not see that there are mast cells on top. These cystic structures are a cystic apocrine glands.
They're also really common in mast cell tumours. So to finish off, I just thought I'd quickly show you a few cases where the cytology has correlated with the histology or not. And the first case I love, this is an 8 month old male German shepherd with a mass on his foot, and even the history should give you the diagnosis.
In this case, this is a diagnosis that was made without any cells at all on the smear. What you can see here is some mineralized granular debris on this smear, and if this was under a microscope, you might even see it's refractile if you focus in and out. And this mineralized debris tells me that what we've got is a calcinosis circumscriptor.
You've got these really big lakes of mineral, squashing the connective tissue in between. And, even if you aspirated the connective tissue, it's almost always full of collagen. There are very few nucleated cells.
They're usually macrophages, fibroblasts, multinucleate giant cells, and even the artefact on this slide tells you you've got mineralized material scraping across. So that's quite a classic diagnosis and a good correlation. This year we've got an 8 year old Labrador with a mass on her shoulder, and I just wanted to talk to you about pigmented lesions and melano melanized lesions, because obviously when we see a pigmented lesion, our immediate thought is, is this a melanoma?
So in this smear here we can see a lot of blood and we can see this greenish black pigment, which is what melanin looks like using the cytology stain. And in this case, most of these cells I suspect are macrophages, but you may be concerned that you've got melanocytes there. However, another field of this stain shows you these clusters of epithelial cells with pigment in them, and the cytologist noted that this could represent a pigmented epithelial neoplasm, like a basal cell tumour.
And in fact, The histology shows just that we have this cystic structure with this proliferative neoplastic lesion in the centre, and when we look on high power, we have these pigmented epithelial cells and these heavily pigmented macrophages on the outside, which shows that this is a pigmented upper con ductile tumour, a benign tumour, and has a much better prognosis than than a melanotic tumour. Just to use this, lesion here, this was a 2 centimetre mass on the left forelimb. Maybe you'll get a histology, a cytology, report back that tells you there was nothing but blood.
We could only find blood. It could be iatrogenic. It could be due to sampling, so the, the cytology is non-diagnostic, and indeed that's what this smear looks like.
Very occasionally, you might see these little loose spindle cells here, but they're, they're not very helpful because they could just simply represent sampling of connective tissue. We don't know. It may be reactive, it may be the edge of a hematoma, we just don't know.
It's not till we get the histology from this case. That we see this well demarcated hemorrhagic mass full of blood-filled spaces which are quite uniform and quite discreet, and this is a benign cutaneous hemangioma. Just finally a word on lymph nodes, I'm just gonna be very quick on this, you can do a whole lecture on this.
If you look at histology specimen here and you see wall to wall uniform lymphocytes, you start to get concerned about lymphoma. If you zoom out of this case, you actually see that I've only zoomed in on a very small part of what is a perfectly normal lymph node in this dog. Cytology specimens can be quite unrewarding from big lymph nodes.
When dogs have lymphoma, the lymphocytes are really fragile and they disrupt very easily, and you might finish up with this image on the left. Alternatively, you can get very, very thick smears from lymph nodes that don't take up the stain very well, and you can't make out the cellular detail to make a definitive interpretation. This is a really nice picture of wall to wall large atypical lymphocytes in a dog which correlates quite nicely with sheets of large lymphoid cells.
We've even got some mitotic figures here that tell you you've got a large cell lymphoma, and that's absolutely classic and easy to do. However, this mixed population from a single large lymph node in an elderly cat is more challenging, and it's not till you see the histology that this is an example of a Hodgkin's-like lymphoma in a single lymph node in an elderly cat. This case here was quite challenging for us.
We had a peripheral lymph lymphadenopathy in a relatively young dog. Our first fine need last, but it showed us nothing, just completely disrupted cells. Our second finding last bit showed us quite a mixed population, but with a predominance of quite large immature cells, here.
So our cytologist did wonder whether we might be getting a very early stage lymphoma or whether this was just a florid reactive hyperplasia. It was very difficult to tell, and we even had a mitotic figure here, which was a bit worrying. However, our cytology showed us a completely normal lymph node.
Now, this cyto this histology, sorry, came a couple of weeks later and it's quite possible that this dog had responded well to anti-inflammatories. I guess if you look at a high powered image just of this area here, if you were to sample this area here, you might see quite a lot of large, lymphoid cells. But just to be aware that lymphoid and correlations are quite tricky.
There are a couple of papers, the one on the left is a, is a human paper looking at subtle changes and then pitfalls of, of looking at hyperplastic lymph nodes, and Patty Ewing from the state has done a really nice summary document with lovely correlating pictures of hyperplastic lymph nodes and early lymphoma which look very, very similar. So if you want to look at them. So how do we look at quality assurance?
Usually if we go back to the gynaecological paper, their first. Vision of this is, is to review all discordant correlations. So this falls with the histologist.
As soon as the histologist gets the histology sample, the, the discordant usually lands on our door, which is probably why I have an interest in it. And it is important for us to know that cytology has been taken and to go back and review that and, and try to explain why they may have been discordant. That, does wonders for improving confidence.
But I would also suggest that you keep a record of. All the cytology that you've done in practise, all the cytology reports that you get back from the pathology lab, and correlate them with the histology that you send in. Review them.
How are we getting on? Are they correlating well? Is there a discordance?
Why is there a discordance? At Nationwide we have weekly histocyto rounds on a Thursday lunchtime. It's a bit of a lunch and learn.
And we look at all of our cases, where we've done interesting ones, ones that haven't correlated, ones that have correlated really well. And lastly, I would say to you, be curious, celebrate the positive correlations as well as learning from the discordant ones, and don't be afraid of them, and don't be afraid of cytology reports that say that it's non-diagnostic. Have a read at the description, see if there are any clues in there as to why it might be a non-diagnostic.
If you've not been bored by this already today, may I suggest and direct you to the British Society of Veterinary Pathology BSVP rounds at the end of October. We're having a histocyto correlation, and if you'd like to join in with that, it is open to non-members that, that evening meeting. Please log on to the BSVP website and you'll get the email address for the secretariat who will send you the link.
I do have a list of references if you're interested, and finally I'd just like to say thank you very much for listening today. It's been a huge task to put this together, so I hope I've summarised it as well as possible for you and if we have any questions, I'd be glad to take them. Thank you very much Sandra, that was er fantastic, such a thorough presentation there, so a big, big thank you.
We have had a couple of questions that have come in so far, so are you happy to stay on for a little bit and take some of those? Yeah. Yeah.
OK, brilliant, so while people are just popping some more questions in, I just wanted to quickly mention, we do have Nationwide's hub which. Is available for people to go and access completely free of charge on the webinar vets platform. So Beck is gonna very kindly pop the link to that into the chat box now, so please do go and check it out, it has so much great content in there, not only webinars, but there's podcasts and I think I even spotted the chance for you to be able to win a webinar vet membership, so definitely go and have a little nosy at that.
OK, so first question that we've had in, how can I use cytology, histology, correlation as a quality control measure in practise? I think it's important, I think, to keep a record, so I would certainly encourage you to look at cytology in practise because I think the more you learn for yourself in practise, the more you will be able to interpret the clinical pathology and anatomic pathology cytology report. So I would suggest you keep a record.
Mhm. And then I would suggest you keep a record of the histology report when that comes back and see if the two correlate yourself. If you can't make head nor tail of them and they can't correlate, we're always very happy to chat about it, and you can record that too.
So I think it's really important that you have confidence in yourself when you're doing cytology and confidence in your laboratory when you're doing cytology. So I think to to start off doing that and not to be afraid if you're getting a lot of non-diagnostic reports, it's important to look into that and find out why. Brilliant, that's great, thank you.
And is there a benefit of sending pre-stained smears for cytology evaluation? I think there is a benefit of sending pre-stained smears. I know I showed you the pre-stained smear that was sent in that we, we decolorized and re-stained ourselves, but I think there is a benefit, and, and the benefit of that is that if you pre-stain, if you send in, for example, 6 smears and you stain 1 or 2 of them before you send them in and you have a quick look, first of all, it'll give you confidence that you've got material on, on the smear and that you are going to get a report.
Back that is, is positive for cells. It helps, your education and your understanding of what those cells look like. So when the, the, the pathologist sends you a report back and they say we saw round cells or we saw big cells or small cells, you can think, yeah, that's exactly what I saw as well.
Or if you see something that you don't understand, and then you read the pathologist's report, you can say, oh, is that what they were? So, I think it is really beneficial to, to send a couple of pristine smears and, yeah. Fantastic, thank you.
Can lipomas be highly cellular and have lots of naked nucleii? No criteria of maligny. So can they be highly cellular and do they have any criteria of malignancy?
I think if you see criteria of malignancy, if you see odd cells in otherwise fatty tissue, then you have to look further. You have to do further investigation. So a lipoma shouldn't have any criteria of malignancy about it.
It very rarely is highly cellular, and the one way I, I would say it would have more cells in it than you would expect is if that lipoma's been traumatised in any way. And we all know the ones that kind of stick out the side of a shoulder or the side of the ribs or something like that, and they're quite used to getting banged and cluttered as dogs are going through doors or or under tables or chairs or things like that, and they can finish up the foci of inflammation in them, and they do look more cellular than you would expect for a lipoma. So it's possible to see more cellular lipomas, but I would be very suspicious if you see what you think are criteria of malignancy, that there's something else going on.
OK that's great, thank you very much, Is it the myoepithelia, I hope I've said that right, cells that differentiate into cartilage and bony tissues in mammary tumours. I think the answer to that is, I don't know, we're not sure. It's tempting to think that it is.
We do think there are some undifferentiated cells, in mammary lesions, and you'll see them in other glandular lesions as well. So you'll also see these in things like apocrine gland tumours in the skin. So whether it's the myoepithelial cells, I'm not sure.
I think we may have to go back a step and look at more undifferentiated cells in these lesions, and I think in mammary glands there are more undifferentiated cells there because of that cyclical nature. There are undifferentiated cells hanging around there that come into play when the bitch comes into season or when she gets pregnant and is lactating, those cells then differentiate. So I think there are maybe more undifferentiated cells in that tissue, and it might be them that are differentiating, but the bottom line is I'm not 100% sure.
But they're really interesting and fun tumours to look at, and they've, they're always crazy and they've got lots of different tissue in them. Fantastic, and then one final, we've had a comment from Selda who has said thank you so much for this great presentation, and then we've had another comment which has just come in which says thank you for the wonderful presentation. In your experience, what is one case you see more often failing to correlate?
For example, low grade sarcoma with granulation tissue. I think you've hit the nail on the head with that one. Our biggest, issue is probably correlating low-grade sarcoma with granulation tissue.
And the truth is, even on histology, we have difficulty with that, particularly if your lesion's inflamed. That can cause a lot of problems. We don't have a specific immunohistochemical marker that will flag up a neoplastic mesenchymal cell from a reactive one.
We have particular trouble with bone lesions. So if we've got any orthopaedic surgeons on here, we really do have a lot of trouble with bone lesions. Reactive bone lesions can look horrific, on his cytology and histology.
So if anyone knows of a marker for, neoplastic mesenchymal cells, I think you'd be a millionaire. OK fantastic, thanks Sandra, that's brilliant, we are out of time, so apologies if there was any questions there that we didn't manage to get to, but just before we close, I just wanted to say a big thank you again to Nationwide Laboratories for kindly supporting this session so that we've been able to bring it to you today. Just a quick reminder that the recording of the session and your CPD certificates will be available on the webinar vets platform within 48 hours, and we will email you once you are ready.
And as always, they will automatically be added to your CPD records. Thanks very much everybody for joining us live and for the excellent questions. We hope you found today's session really valuable and that we will see you on another webinar very soon.
Big thank you again, Sandra. Really appreciate it. Thank you.
Thanks everyone. Bye, bye.
