What’s the Scoop? Tips for Better Biopsies

When should you scoop? When should you shave? How large a sample do you need? And where do you sample from? When it comes to biopsies, you may have questions. And double board certified dermatologist and dermatopathologist Michelle Hure, MD, has answers in this episode of the Dermalorian™ Podcast. Plus, Lisa Swanson, MD gives the straight scoop on skin care for kids and Geroge Keough, MD addresses the issue of clinical mimics.

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Transcript

Please note that the transcript has not been reviewed or edited for accuracy. It is provided as a courtesy only. 

Welcome to The Dermalorian Podcast from the Dermatology Education Foundation. Are you prepared to spot common mimics in your office? Are you ready to give skincare advice to kids? Believe it or not, they're asking. We'll get to those issues in this episode.

But first, Dermatologist and Dermatopathologist Dr. Michelle Hure, founder of OC Skin Lab in California, has tips for selecting the right type and site for a biopsy. She says that, "The dermatopathologist can't always offer a definitive diagnosis, but with the right clinical clues and specimens, they can often come close."

Our goals are going to be to give, "Well, what is the most likely diagnosis?" That is really coming down to identifying the changes that we see in the epidermis, the dermis, the fat. What type of cells? The distribution of the inflammation. These are all clues that are going to give us more of an idea of the diagnosis, but it may not be definitive. We'll go over that, because I know it's very frustrating for clinicians to not have a definitive diagnosis. But in the end, we all have the same goal of helping the patient and doing what's best for them.

Let's really break apart what you should be putting on your pathology requisition forms. This is a sample path requisition form that I have in my office. Whatever you can do, take the time to really either review what your MA has written, or fill it out yourself. Because I promise you, if you just leave it up to your MA, you may not get all of that pertinent information that the dermatopathologist needs. If you just put neoplasm of uncertain behavior, or just hair loss, you may not be getting the best diagnosis back because we need to know all of the information.

If you're worried about a malignancy, I need to know the location, how long it's been there. Has it had a prior treatment? Has it had cryosurgery? I need to know all of these things. If it's a dermatitis, has it been partially treated in the past? I need to know everything because that is the only way that I can give the best diagnosis. That clinical pathologic correlation is vital in dermatopathology because the same lesion, if you look at a lesion under the microscope, could look exactly the same in, say a four-year-old or an 80-year-old, on different parts of the body. Even though it looks exactly the same under the microscope, they will be totally different diagnoses. It all depends on the clinical history.

Make sure you are doing everything to fill out these requisitions appropriately. I know a lot of people say, "Oh, I don't want to bias that pathologist." I promise you, you cannot bias us. It's okay. We got our big girl pants on. You will not get bias. But we do need to have all of the information to make the best diagnosis for you.

Let's talk about some of the biopsy techniques. Everybody knows punch biopsy. The punch biopsy is you're actually taking a full thickness, basically sample of the skin. It's a column, a column of tissue. If you're only taking, say a millimeter down, you take a four-millimeter punch biopsy but you're just doing a little bit on the top, you don't want to go too deep, that is basically a shave biopsy. You're wasting that punch biopsy. You need to get that full thickness to look at the upper part of the dermis, the lower part of the dermis, the fat. This is very important.

Now this is pretty much the necessary or preferred thing to do for inflammatory lesions. But I promise you, and I'm going to go over this over and over in this talk, it is not recommended for pigmented lesions. I know you're going against that in your head, but it's not. Unless you can remove the entire lesion. I promise you, and we'll go over this over and over in this talk, and you will be a convert to this.

Now, what other techniques? Superficial shave biopsies should only be done with things you know are benign, they're probably cosmetic removals. Maybe a pedunculated mole or a skin tag. You're basically cutting it back to the surface of the skin. These are not really what we're going to be talking about when we talk about shaves during this talk.

What we're talking about mostly is saucerization, or a scoop shave. This is a great way to completely sample your lesion and give enough in that depth to look under the microscope. If we have, say a melanoma, and we need to see a little bit of a depth of invasion, this is enough. This is really important to hammer home tonight, is that when we do a saucerization or scoop shave, we are absolutely getting enough depth and enough breadth to make the best diagnosis. Because what this is, is basically we're getting all of the epidermis, and part of the upper dermis. I promise you, that will be enough for a biopsy and for a report that is adequate for melanoma.

The thing that you want to really punch is that person that told you you should be punching all pigmented lesions. It's not going to help you unless you absolutely can get the entirety of the lesion out with your punch. If this is a four-millimeter biopsy, that's great. Take it all out, I'm fine with that. Although, you could just shave it. If you're still questioning this, you really need to have breadth over depth.

They've actually looked at this in studies. If you do a partial biopsy of a larger lesion, less than half of the lesion, 50% or less is actually looked at, so biopsy. Upstaging occurs in a pretty big percentage of these cases when they go to excision. This was either a punch or a partial shave of these lesions. If you are only taking a little snippet of a pigmented lesion, there's a great chance that it's not going to be the right diagnosis. Or it's going to be not the best diagnosis. Don't fear that scoop shave. I promise you, you will give at least a millimeter of depth with that biopsy.

Why is a millimeter so important? We're talking about staging. If you do have the melanoma, and the most important thing is making that diagnosis of melanoma. And am I going to get a [inaudible 00:07:14] lymph node? That is going to be determined by the stage. If you have a melanoma that is invading down to about a millimeter, you're going to get a lymph node. Sometimes even less than that, like .85, sometimes .75. It depends on the other features. As long as you're getting a millimeter, you are fine. You're going to be okay. If these are way more invasive, you'll find that on the re-excision. But don't worry about this. This is where, most likely, your melanomas are going to be anyway.

What about inflammatory? Shaver patch. What do we do? Okay. Unfortunately, it's complicated. It's not always the same. Everything is always the same, you always have to punch the inflammatory. But more or less, the rule of thumb is you shave the neoplastic and you punch the inflammatory. We have exceptions.

This patient was added on to my clinic at the very end of the day, I had about 15 minutes to see him. This was a dermatitis that had been going on for a long time. It was itchy. They'd gone to primary care and was given a couple of different steroids. It wasn't really helping, maybe a little bit. I thought, "Oh my gosh, I don't have time to punch this." But I looked at it, I felt it, it was not indurated. It's probably not a dermal process. It was a little scaly, so it's most likely going to be on the superficial aspect. It's probably an epidermal lesion. I went ahead and I shaved it, instead of punching, and it ended up being a tinea incognito. Cool. I was all right not punching it.

Okay. Then this patient comes in from another office, and had been treated multiple times with cryosurgery for a scaly spot thought to an actinic keratosis. It just wouldn't go away, and it keeps getting this little indentation. Maybe that's from repetitive treatment with liquid nitrogen and scarring. But here's the problem. I know, because this patient has been treated previously, that the top is going to have a scar. We need to see underneath, make sure there's no other process going on underneath. It would be very, very easy just to shave this, but I decided to do a punch. I know it's a weird location. But the punch did show a deep infiltrated basal cell carcinoma, which did lead to a pretty significant mohs surgery. Had I just shaved it, I would have missed it and only seen the scar from prior surgery.

There's always exceptions to the rule. Use your clinical judgement. Of course, 99% of the time, you're going to be fine with the punching inflammatories and shaving neoplastics.

Knowing when to punch is just one part of the equation. Knowing where to punch is just as important. We'll get to that in just a moment.

But first, here's this episode's Dermalorian Derm Decoder. September is Skincare Awareness Month. Increasingly, the skincare industry is marketing products to tweens and teens. Pediatric Dermatologist Dr. Lisa Swanson shares her tips for talking to patients about skincare.

When I'm talking to patients and their families about the importance of good skincare, I lay out a couple important lessons.

Number one, simple is better. Keep it simple. Sometimes when people are using all sorts of stuff that they've purchased on Amazon, they're exposing themselves to potential contact allergens. The simple stuff is great. It's often cheaper than the fancier stuff. You don't have to spend a lot of money to get good quality skincare for patients and their families. I recommend keep it simple.

I also tend to give them my list of favorite things. I have a list called Dr. Swanson's Favorite Things. It includes a sensitive skincare section, a face care product section, a sunscreen section. It helps me so much in any given day, to have all those recommendations written down. I often tend to write notes for patients on the flip side of it. I give them something that has the notes from their visit that day, and also a list of products that I recommend. It has made my life so much easier to have that list because I found myself writing down the names of the same products over, and over, and over. Finally, I was like, "I should just make a list." It has saved me oodles of time over the past few years.

When it comes to skincare and kids, I think there's two categories of the pediatric patient population. There's the young child, and then there's the pre-pubertal and pubertal teenager. For the young child, we want to use sensitive skincare. Especially for those who have eczema, but really all young child's skin is more inherently sensitive as it develops into itself and matures over time. Utilizing sensitive skincare products is never wrong for the younger patient population.

For patients as they approach puberty and enter puberty, you want to talk about the importance of basic good skincare. Wash your face. It was funny, because when I started in practice, I would ask teenage boys questions like, "What do you use to wash your face? How many times a day do you wash your face?" I learned over time that I needed to start lower than that. I needed to start with, "Do you wash your face?" And then build from there, based on the answers. The importance of washing your face twice a day with a basic gentle skin cleanser. Using a face lotion with sunscreen in the morning, and a face lotion without sunscreen at nighttime if your skin needs that. Keep it simple. That's the most important part.

Let's get back to Dr. Hure and her tips on choosing the best biopsy sample.

Okay. Where do we punch? That's a common question. If this patient comes into your office, this is a big area. Where are we going to punch? Do we just close our eyes, and point, and just pick a spot? No, no, no. We have to think about this.

You want the lesional skin, this is very important. We always ask, "Is it perilesional, lesional?" You definitely want lesional skin. But what part of the lesion? You want to have the leading edge, the newest spot. Ask your patient, "What is the newest spot that you have?" And a spot that hasn't been treated.

So often, these patients come in and they say, "I had some steroids that someone gave me in the past, and I just threw it on there. It didn't help." Show me the spot that's new that you haven't treated. That's what I want to biopsy. Always, always, always. Because if you biopsy in an area that's older, it's burned out, you're going to have very bad diagnosis in that you're not going to provide the pathologist with enough clues to point us in the right direction because it's burned out.

The same thing goes for, say an alopecia, a scarring alopecia. If you take a biopsy in the scarred part, guess what you're going to see on the slide? You're going to see a scar. These patients are already traumatized, they're alopecia patients. There's a lot of emotion around it. None of them want to get biopsied. Then you biopsy a spot that's not helpful. Then you're going to have to go back and do another biopsy. Where do we still have some follicles, maybe a little bit of erythema? Probably more of an active site, instead of burned out.

Then if you do have any bullous, blistering disorders where you're trying to do a punch for a DIF, that's where you want to get the perilesional skin. If you punch the lesion, if you actually punch the blister for a DIF, then you will most likely get a false negative. You're going to want to get the perilesional skin. That is super critical.

Okay. I am going to hammer this home because it's so important. Inadequate sampling. So partial biopsy of a larger lesion. If you have a big spot, and only one little area is malignant and you don't get that area in your biopsy, then that's the problem. It's really important to give that breadth. That's the most important thing.

I also see, a lot of the times, some biopsies are very superficial. This is really important when we're talking about ruling out things like a vasculitis or panniculitis. For vasculitis, we want to see the vessels. We need to see the vessels on the superficial plexus as well as the deep plexus. You do need to get that full thickness. If I had $1 for every case where it was rule out panniculitis, that's the fat inflammation, that actually had no fat on the biopsy, I would probably be able to afford a Starbucks. But it would be a lot. It would be a lot. It's really important to get that full thickness and get the area of interest.

I see this most commonly when patients are biopsied for squamous cell carcinoma on acral surfaces, so if you're on your hands and feet. Because the skin is so much thicker in that area, the stratum point of the dead skin layer on top, it is thicker. You think you're doing a nice, big scoop shave, but you're still midway through the epidermis. You're going to get a transected squamous proliferation, and you're not going to get an adequate diagnosis. What's going to come back is the dreaded atypical squamous proliferation, can't rule out underlying squamous cell carcinoma because it's transected. Then you're going to go, "Ugh!" This is why, it's not deep enough.

Again, not enough tissue for appropriate diagnosis comes in with alopecia. You already have, again, that traumatized patient who has hair loss and we have to biopsy. We need to make sure that we're giving an adequate biopsy to the dermatopathologist because we have to look at particular things for alopecia. Not only do we have to look at each hair follicle going from the top of the skin down to where it inserts in the mid-dermis at the bulb, we need to see that full thickness follicle. We also need to see all of the cross-sections of the follicle. We need to see them all at once. Which means these have to be cut differently. If I only get one small biopsy, I will not be able to thoroughly examine both the vertical as well as the horizontal cross sections. You're going to get an inferior, or even an inadequate for a diagnosis biopsy.

Also, for cases where you're really worried maybe about a lymphoma, or maybe a metastatic lesion, those cases are going to probably need a lot of workup, which means a lot of stains, maybe molecular studies. The tissue is going to be exhausted, meaning you're going to run out of tissue at some point. You may have to do another biopsy. Get a big chunk and make sure you send it to the lab with that.

You can get more from Dr. Hure on The Dermalorian Webinars page at dermnppa.org.

Now, for this episode's Dermalorian Clinical Clip. Why is it important to be on the lookout for mimickers in dermatology? Dermatologist Dr. George Keogh explains.

You have a middle-aged man with an erosive tumor in a sun-exposed area in the face. You would think at first sight, "Aha! This is basal cell carcinoma." However, you notice upon talking to the man that he has very poor dentition. Then you look into his mouth and you see a lot of poor dentition, and you happen to notice inflammation in the same locale as the skin lesion. Indeed, this is not basal cell carcinoma, this is a dental sinus that can look very much like a basal cell carcinoma. This patient does not need a mohs surgeon, this patient needs to see a dentist. That's mimicry. You have the dental sinus mimicking a basal cell carcinoma.

Another one is pityriasis rosea. We see this in children, we see this in adults. We see a very simple rash on the body and we think, "Aha! Pityriasis rosea, we see this all the time." However, secondary syphilis is almost indistinguishable from it. That mimicry can be very dangerous. You don't want to tell a patient, "You'll be better in a couple of weeks." Sure enough, their secondary syphilis lesions go away, and later down the road they have many problems in the tertiary form.

You want to do a little bit more. You have to sometimes ask the difficult questions. You sometimes have to do blood work. You have to use your experience in order to make the correct diagnosis and avoid being fooled by a mimic.

Thank you for joining us for The Dermalorian Podcast from the Dermatology Education Foundation. If you're new to our series, welcome. Check out our past episodes wherever you listen to pods. Share The Dermalorian Podcast with a colleague. We'll see you next time.