This is Lab Medicine Rounds, a curated podcast for physicians, laboratory professionals, and students. I'm your host, Justin Kreuter, a transfusion medicine pathologist, assistant professor of laboratory medicine pathology at Mayo Clinic. Today, we're rounding with doctor Aaron Downs, professor of laboratory medicine pathology and anatomic pathology at Mayo Clinic in Arizona to guide us through the world of benign mimics of malignant breast pathology. Thanks for joining us today, doctor Downs.
Thanks so much for the invitation to be here.
So I wanna maybe kick off our conversation with why is it important to appreciate mimics in breast pathology?
Sure. You know, a lot of times we're making a diagnosis based on a core needle biopsy, and this is oftentimes the patients lead off into how they are going to be treated in the future. So if we're talking about something that's benign, this may mean that their follow-up may just be watchful waiting or additional imaging. If it's something that's malignant, it may mean they're going to go to the Operating Room and have a procedure. They may need chemotherapy or even radiation.
So we really want to make sure that we are appropriately classifying these lesions so that future treatment can really be appropriate.
Right. So it sounds like there are a lot of different directions that things can go, and I'm impressed to think about these. You were saying, you know, it's a needle biopsy, so it's really kind of a minimal tissue that you're getting to evaluate the pathology in a needle.
Correct. It is. So I think it's important to remember that, you know, we're dealing with a small sample of a larger lesion. A lot of times, though, these are fairly representative of what is going on. So there are times when we are I would say the majority of the time, we are actually able to render a diagnosis and then, you know, treatment goes forward.
There are times, though, when it's probably best serving the patient to leave a diagnosis as somewhat ambiguous, and admit that some of these lesions, we just need to look at more tissue. So we try really hard to get to a diagnosis, but I think there's also some uncertainty, and uncertainty is something that you have to, I think, get comfortable with pathology.
I think that's something I'd like to highlight for our student listeners because sometimes we have people apply for residency in pathology, and sometimes it's with the perception that things are black and white in pathology. And I think you're highlighting that, hey, this is clinical medicine too. There are challenges. So can you share a couple of examples of where you can have mimics maybe in either direction in breast pathology?
Sure. So there are a couple of lesions that I kind of hold in my mind to be aware of. Something like organizing fat necrosis, totally benign process that we see frequently in the breast, happen after an injury, can happen after prior surgery or prior biopsy. So we see organizing fat necrosis, right? That's benign lesion.
The mimic of that that is malignant is something called an invasive carcinoma with histiocytoid features. Vatnacurus has a lot of histiocytes, as the name implies. Invasive carcinoma with histiocytoid features looks like histiocytes, and they can be really bland and really tricky. So something I learned during residency was kind of this whole concept of a triple test in breast pathology, where the imaging has to match the clinical, and it also has to match the pathology. So if one of those is not adding up, beware.
And really think about, Gee, is this really fat necrosis, and does this patient have a reason to have fat necrosis? Or maybe should I put a cytokeratin stain on this and make sure I'm not missing something? That's
sneaky For our listeners that may not be familiar and have experienced breast sign out pathology, can you elaborate about that, that idea of this triple test about how does that conversation happen between what the imaging looks like, what the pathology is showing, what the clinical how is that navigated in clinical medicine as an example?
So I can think of examples when maybe the imaging says, I've got these really worrisome microcalcifications and you are cutting into a tissue block and you see, you know, well, there's a couple microcalcifications there, but I don't have any real epithelial changes associated with these microcalcifications. It's really important to go and look and correspond with the specimen image. So when the radiologist takes this biopsy for microcalcifications, they actually image those cores that they take, and you get an idea of how many microcalcifications are there. And then when you look under the scope, you need to make sure that what you're seeing matches what was there. So if you're not seeing many microcalcifications in comparison to the specimen image, it would really behoove you to go deeper into that block, that tissue block, look at more levels and really make sure you've accounted for that.
So that's an example of using data that's in Epic that we know about the imaging to guide what we're doing. You know, sometimes it's a conversation with the radiologist, too, that says, you know, How concerned are you about this lesion? Did this lesion maybe dissipate after you took a core needle of it? Maybe that's a cyst. That information would be good to know before we really level into a block and chase something that maybe isn't there.
Versus them saying, you know, I'm really worried about this, and we cut levels and we're just not seeing what can account for that mans lesion. And I think, you know, then they reconcile that, and maybe our biopsy really didn't sample what we wanted it to.
I see. So it's a nice way to verify that we got this needle. Is this representative of the lesion that we're going for? Or maybe we missed it or we need to take a different approach to it.
see. How do you navigate that in terms of training, like thinking back to your own training in this and doing this comparison and understanding what can account for we have the lesion. I guess what I'm getting at is, what's the experience of learning how to approach and navigate these challenging waters of mimics?
You know, unfortunately, sometimes it's just life. It's time at the microscope. I can remember when I was a resident, I had and it was almost near the end of my residency, and I was going to do a breast fellowship. I had an attending tell me, you know, you're a pretty good resident, but just so you know, you're not going be really good until you're about five years out. And I was like, Oh, well, that's really disappointing to hear.
I look back now and I understand what he was getting at, that it is time in the saddle and it is time dealing with different situations that arise. And the longer you do this, the more you are cognizant of the different things that you're going to run across. So in training, you hear a lot about them, and then I think it's maybe not until you are actually faced with working one of these lesions up that it everything starts to fall into place, and and you begin to learn to work through these a bit more.
I've heard people sometimes talk about we don't learn from experience, but the idea we learn from reflecting on experience. And so I'm curious, what's your approach of capturing the learning when you come across one of these mimics? And and after you navigate it, are there certain ways you're reflecting and thinking about the case? For example, maybe appreciating, was there some nuanced piece of this that made this one different than others? How do you go about that?
So I'm always appreciative of having clinical history. I think clinical history and knowing what has gone on with the patient is really important, and that can really save you from potentially going down the wrong road. You know, in breast pathology, sometimes we deal with metastatic lesions to the breast, and if you don't know that this patient had a history of an ovarian serous carcinoma, then you may misinterpret something that looks like micropapillary carcinoma as a breast primary. So, knowing clinical history and having a heightened sense for this looks micropapillary, maybe I don't have any information on the patient, Maybe I should do a couple of immunostains and just make sure that what I'm really dealing with this is a breast primary. Another thing is use your colleagues.
A lot of times, I may be going down a road on something and and think I'm I'm headed in the right direction, and it's always good to phone a friend and and show a case around and make sure that, you know, these different sets of eyes and this different knowledge base that's that's there is thinking, yeah, you're on the right page or, man, we you gotta do you really need to do some other things with this case.
I I think for the clinicians that are listening to this podcast, to highlight your your point out about knowing the clinical history is really important. I think sometimes people feel like, well, we shouldn't tell the pathologist what's going on or what we're suspicious of because we want to have, like, an unbiased read. Right? But what would you say to them just to kind of underline and highlight your point on the clinical information is helpful?
Yeah. You know, pathology is not practiced in a vacuum. That information is so important to know the history. And do you run a risk that it biases you? Sure, you do. But you also owe it to the patient and to yourself to incorporate that information, not let it bias you, and then prove to yourself what's happening and what's going on, and using the medical history to help you, not bias you, but to bolster your diagnosis.
Along those lines, I wonder, thinking about another segment of our audience, maybe the young professionals, you know, in those first five years out in practice. You mentioned showing the case to colleagues. And what are some best practices on how you go about showing a case to a colleague? What's a way that you can do that that kind of respects their time, highlights what issue that you see or question that you have? What does that look like when you ask a colleague for help?
Sure. I'm lucky. I have wonderful colleagues that their doors are always open, I can just walk in their office and say, hey. Can you look at this case? Not everybody's gonna be in that same situation, and I think it's important to also know that, you know, a lot of people are busy.
So if it's reaching out and saying, Hey, I have a case I'm struggling with. Can we make a time to sit down together and look at this? You know, being respectful of someone's time, being prepared with, here are the pertinent slides. Don't follow-up with the two trays of slides and say, please help me find the microinvasion in this. Anyone with 50 trays of ductal carcinoma and say to, you know, have a good idea going in what your questions are and to show them the the pertinent information or the pertinent slides, but also come with the pertinent information and and the history that's relevant to the case too.
Oh, it's wonderful, wise words for the audience. Maybe as a final question, I'm curious on these as diagnostic challenges. Is this a situation where these mimics are kind of a static thing and we just need to kind of train to them and they're gonna persist in being a diagnostic challenge? Or do you see future, I don't know if it's immunostains or if it's AI technologies that may change what we see as a mimic?
Sure. I think, just looking back since I've started, I can think of examples of cases that I would have signed out very descriptively at one point, like low grade spindle cell neoplasm, right, and listed what the differential was. Could be a fibromatosis. The immunostains don't really support it, but maybe it's a low grade fibromatosis like metaplastic carcinoma. Big difference in those two diagnoses.
Just with that as a specific example, the thinking about that has changed, and you can actually look for typical molecular alteration in fibromatosis and use that to help you make that diagnosis. And then you are much more specific in what you are calling this low grade stem cell neoplasm. And I think you are doing a much better service to the clinicians and frankly to the patient as well. Because certainly the treatment of that lesion in particular has changed over time. So much like our diagnoses in that realm have changed somewhat over time because we, you know, we have molecular data, so so has the the treatment of them.
So I think molecular plays a big role. Certainly, immunohistochemistry, as as new stains come on board, plays a big role. And I would imagine you mentioned AI. I would imagine in the future, sure, I think AI will probably play a role as well. I think we're a ways from it, but I think it's I think we're not getting away from it.
A wonderful world in pathology. We've been routing with doctor Downs talking about benign mimics, malignant breast pathology. I really appreciate you taking the time to talk with us today, doctor Downs.
Thank you so much for letting me be here.
To all of our listeners, thank you for joining us today. We invite you to share your thoughts and suggestions by email to m c l education at mayo dot e d u. If you've enjoyed this podcast, please subscribe. And until our next rounds together, we encourage you to connect lab medicine and the clinical practice through educational conversations.