Five Things You Should Know Mohs Surgery Skin Cancer

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Five things to know about Mohs surgery for skin cancer

Mohs surgery is a quick and highly effective procedure designed to treat skin cancer. We asked Dermatologic Surgeon Ian Maher, MD, a Mohs surgery specialist, to tell us more about this procedure.

  • September 05, 2018
  • By Staff Writer

Ian Maher, MD, just wants to make things quick and easy for skin cancer patients.

Maher is a dermatologic surgeon with University of Minnesota Health and an associate professor in the University of Minnesota Medical School’s Department of Dermatology. He is an expert in Mohs surgery, a surgical technique that treats skin cancer by gradually removing thin layers of skin from a skin cancer site until a patient is cancer free. Unlike other skin cancer surgeries, Mohs surgery can be completed in just a day with same-day testing that gives patients greater peace of mind. The procedure is essentially painless and is highly effective. It can be used to treat basal cell carcinoma and squamous cell carcinoma, in addition to melanoma.

A West Virginia native, Maher also treats other complex skin tumors and performs reconstructive operations after skin cancer surgery. Maher is considered a national expert on post-skin cancer reconstruction, lectures extensively at national meetings and is the author of over 40 peer-reviewed publications and a dozen book chapters. We caught up with Maher to talk about five things we should know about Mohs surgery.

Mohs surgery is very precise.

During Mohs surgery, a dermatologic surgeon like Maher removes skin from a skin cancer site one stage at a time. First, a dermatologic surgeon outlines the lesion with ink to map the tumor. After a local anesthetic is injected, the doctor removes the thinnest possible layer of cancerous tissue. While the patient waits, that layer is processed in an onsite pathology lab. After processing, the dermatologic surgeon can then examine the entire margin of removed tissue under the microscope to determine whether any cancer remains. If skin cancer persists, the dermatologic surgeon can identify the precise location of the remaining cancerous cells. At that point, the patient returns to the operating room so that the surgeon can take another layer—and the process is repeated until all cancerous tissue has been removed. Roughly 80 percent of patients only need a single layer of skin removed in order to remove all the cancerous tissue. This layer-by-layer approach keeps the incision as small as possible to reduce scarring and promote healing.

In traditional skin cancer procedures, a pathologist may only study a small fraction of a much larger sample to determine whether any cancer remains, and the results often take days to process. Surgeons like Maher have been trained to act as both the surgeon and the pathologist. They remove the tissue, then conduct a comprehensive study of the entire sample to ensure a patient is cancer-free before moving on to reconstructive surgery. Maher has performed over 10,000 Mohs procedures during his career.

“Because of the way we process these tissue samples, looking at 100 percent of the margin, we can know for certain when we’ve removed all of the cancer,” Maher said.


Mohs surgery leaves less scarring.

Because of its incremental and precise approach, Mohs surgery requires a smaller incision, which minimizes the amount of reconstructive surgery needed and reduces scarring. The process removes a minimal amount of normal skin surrounding the cancer—only taking what is needed to remove the cancer.

“Because we check the entire surgical margin, we are able to spare more normal skin, resulting in a smaller incision,” Maher said. “We always strive for the repair that leaves our patients with the best cosmetic and functional result. Our goal is to minimize scarring so that someone looking at you from a normal distance wouldn’t be able to tell you’d had had a procedure within three months after the surgery.”

Maher works with his patients to find a plan to return them to their normal appearance as quickly as possible after surgery.  “Everybody is different, and I strive to get my patients the best cosmetic result possible with a plan that fits their life.”  Maher has also developed and published a number of new reconstructive techniques, particularly for the nose and ear.


The procedure is quick and efficient.

Because the dermatologic surgeons that perform these procedures act as both the surgeon and the pathologist, they are able to complete these surgeries in just one day. In traditional methods, surgeons and patients may be required to wait several days before learning from a pathologist whether any cancerous tissue remains around the surgical site.

“We’re able to process the tissue, look at it within an hour, evaluate it and then take more, if necessary,” Maher said. “We don’t move onto the repair until we know we’ve gotten the entire tumor. Most patients spend between two-and-a-half to four hours with us the day of the surgery.”

It has a high success rate.

Mohs surgery is speedy and efficient, but is also one of the most effective forms of treatment for certain types of skin cancer. For a standard skin tumor that’s being treated for the first time, the success rates are as high as 98 to 99 percent. “This type of surgery offers one of the best cure rates for many types of skin cancer,” Maher said.

Mohs surgery is nearly painless.

Apart from the injection of an anesthetic to numb the area prior to the procedure, patients will be experience very little pain during or afterward. If patients are anxious about the procedure, our dermatologic surgeons can give them an oral medication in addition to the anesthetic to help them relax on the day of their Mohs surgery, Maher said. “Typically, pain after the procedure is minimal and can be relieved by over-the-counter medications like Tylenol or Advil,” Maher said. “Less than five out of every 100 patients require prescription pain medications, and the vast majority of people have a pain level of 0 out of 10 within 48 hours.”

Editor's note: This article was originally published on March 3, 2017, and has been updated to ensure continued accuracy and comprehensiveness.