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HOST (Mark Houston): Hello again, everybody, and welcome to Doc Talk with Monument Health. I’m Mark Houston, and joining me again is Dr. Gasbarre, a dermatologist with Monument Health in Spearfish.
Welcome back, doctor. I appreciate you taking the time to come all the way over.
Dr. Gasbarre, D.O.: No problem. Thanks for having me.
HOST: Last time we talked, we covered the basics of skin and skin cancer—what to look out for and when to be concerned. Today, I want to focus on a procedure you specialize in. You even completed a fellowship in it.
It’s called Mohs surgery, correct?
Dr. Gasbarre: Correct.
What Is Mohs Surgery?
HOST: Walk us through how this works.
Dr. Gasbarre: Mohs micrographic surgery was developed by Dr. Frederic Mohs. He first described the procedure in the late 1940s and early 1950s. It has evolved significantly since then, with modern techniques really taking shape in the late 1970s and early 1980s.
What makes Mohs surgery unique is how we remove and examine the tissue.
We remove a piece of skin that contains the cancer, along with a very narrow margin around it. Then we process that tissue in an on-site lab so we can examine 100% of the surgical margins.
Think of it like peeling the outer layer of an onion and laying it flat. We’re looking specifically at the outer edges—the circumferential margins—to see if any cancer cells remain.
How Mohs Surgery Differs from Traditional Methods
Dr. Gasbarre: Traditionally, when a pathologist examines a biopsy, they slice the tissue like a loaf of bread. That helps identify what the tissue is.
In Mohs surgery, we already know what the cancer is. What we care about is whether we’ve completely removed it.
Skin cancers grow outward in a continuous pattern. They don’t typically “skip” areas. So if the outer edges are clear—both the sides and the deeper margin—we know we’ve removed the entire tumor.
Because of that, we don’t need to take large amounts of surrounding healthy tissue.
HOST: Is that how it used to be done?
Dr. Gasbarre: Yes, and it still is in some cases. That approach is called a wide local excision, where we remove a larger margin of tissue based on established guidelines.
With Mohs surgery, we can start with a margin as small as one to two millimeters and only take more if needed.
Cure Rates and Benefits
Dr. Gasbarre: Mohs surgery offers two major advantages:
High cure rate – about 98–99%, which is the highest of any skin cancer treatment
Tissue preservation – we remove as little healthy skin as possible
This is especially important in areas like the nose, where even a few millimeters can significantly impact reconstruction.
Scarring and Cosmetic Outcomes
HOST: That leads into one of the biggest concerns people have—scarring, especially on visible areas.
Dr. Gasbarre: Any surgery will create a scar, but Mohs surgery minimizes it by preserving as much normal tissue as possible.
Because of that, we typically reserve Mohs surgery for:
Cosmetically sensitive areas (face, nose, eyelids)
Functionally sensitive areas
Areas with higher risk of recurrence
For example, a small skin cancer on the back would not usually require Mohs surgery. Other treatments would be more appropriate.
High-Risk Areas for Skin Cancer
HOST: Where are the highest-risk areas?
Dr. Gasbarre: We refer to the “H-zone” of the face, which includes: Eyes, nose, lips, ears, temples
Other high-risk areas include: hands, feet, genitals
Many people assume skin cancer only occurs where the sun hits, but that’s not always the case.
For example, squamous cell carcinoma can be associated with human papillomavirus (HPV), especially in the genital region.
HPV and Skin Cancer
HOST: That’s the same HPV we hear about with vaccines, right?
Dr. Gasbarre: Yes. There is a vaccine that targets the strains most commonly associated with cervical cancer.
It’s still a bit early to know how much impact it has had on skin cancers specifically, but we expect it to help over time.
We also occasionally see skin cancers around the fingernails, which can be related to HPV as well.
Where Skin Cancer Is Most Common
HOST: So the most common location overall?
Dr. Gasbarre: For non-melanoma skin cancers, the head and neck are the most common areas, with the nose being the single most common site.
The Mohs Surgery Team
HOST: How many people are involved in the procedure?
Dr. Gasbarre: It’s definitely a team effort. We have:
Nurses and medical assistants, A histotechnician, who processes the tissue
The histotechnician plays a critical role. They take the tissue, freeze it, and prepare thin sections so I can examine them under a microscope.
It’s a highly skilled process.
How the Tissue Is Processed
Dr. Gasbarre: The tissue is embedded in a gel-like medium, frozen, and then sliced into very thin sections.
This allows us to examine the margins in real time—usually within 30 to 45 minutes—so we can decide whether additional tissue needs to be removed.
Depth of Skin Cancer
HOST: How deep can these cancers go?
Dr. Gasbarre: Most are limited to the skin and upper fat layer. But in more advanced cases, they can extend deeper.
I’ve seen cancers: Reach the surface of bone, Track along nerves, Extend behind the eye, Destroy parts of the nose
These cases are rare, but they highlight why early detection is so important.
Recovery and Healing
HOST: What does recovery look like?
Dr. Gasbarre: If stitches are used:
They’re typically removed in about one week on the face
The wound is noticeable for about six weeks
Significant improvement occurs around 3–5 weeks
Full scar remodeling can take up to one year
Can Skin Cancer Spread?
Dr. Gasbarre: Yes. For example, squamous cell carcinoma can spread to lymph nodes, although the risk is relatively low—around 5%.
When it does spread, it can be aggressive.
What’s Next in Mohs Surgery?
HOST: What’s next in this field?
Dr. Gasbarre: One advancement is immunostaining, which helps us better identify certain cancers like melanoma during Mohs surgery.
This technique uses antibodies to highlight cancer cells under the microscope. It’s more commonly used in larger centers.
Looking ahead, the goal is to develop treatments that offer the same cure rates without surgery.
Dermatology in Everyday Life
HOST: Since skin is so visible, do you ever see something on someone in public and feel like you should say something?
Dr. Gasbarre: It does happen. You have to be very thoughtful and respectful about it, but if you believe something could be serious, there is an ethical responsibility to help guide someone.
HOST: Dr. Christopher Gasbarre, dermatologist with Monument Health in Spearfish—thank you again for coming in.
Dr. Gasbarre: My pleasure. Thanks for having me.
HOST: Anytime you want to talk skin, we’ll do it.