Mohs surgery was developed by Dr. Frederic Mohs in the 1930s at the University of Wisconsin. It is a specialized outpatient procedure for removing skin cancers that provides a high cure rate and saves as much normal, healthy skin as possible.
Mohs surgery is suitable for skin cancers that:
- Are located in areas where it is important to preserve as much normal, healthy tissue as possible for the maximal functional and cosmetic result
- Have come back after previous treatment
- Are large, aggressive, or growing rapidly
- Do not have clearly defined edges
- Develop in organ transplant or other immunosuppressed patient
What Happens During the Procedure?
The Mohs micrographic surgery procedure is described and illustrated below:
- Local anesthetic is injected to numb the area
- The area of the cancer is removed so that the entire undersurface and skin edges can be examined microscopically.
- Tissue is dyed, and a map is drawn so that the tumor found can be located on the patient. Tissue is processed onto microscopic slides.
- The surgeon examines the slides under the microscope. If cancer cells are found, they are marked on the map to guide the surgeon in removing additional tissue.
- Layers of tissue will be removed until no cancer cells are found.
Hear Dr. Brady discuss Mohs surgery for skin cancer as part of our new Cancer Talk podcast series. Subscribe via iTunes and iHeartRadio.
The Mohs Micrographic Surgery Procedure Description and Illustration
What is the Advantage to Mohs Surgery?
This has a very high cure rate for skin cancer because the surgeon confirms through microscopic analysis that the entire tumor is removed during the procedure. It traces the cancer to its root through the mapping process and excises it.
You want your skin cancer to be treated by a fellowship-trained Mohs surgeon who is a member of the American College of Mohs Surgery (ACMS). This organization requires its physicians to undergo at least one full year of training and hand-on experience beyond dermatology residency. To become a member of the ACMS, physicians must complete at least 500 cases of Mohs surgery and reconstruction. The Mohs surgeon serves both as the surgeon and pathologist (a doctor who identifies disease by studying cells and tissue under a microscope).
Mohs surgery requires a team approach. In addition to your surgeon, there will be a nurse practitioner or physician assistant who will be assisting at the time of surgery, a specialty-trained nurse or medical assistant, and a histotechnologist who prepares the microscope slides.
How to Prepare for this Procedure?
If any medications need to be discontinued, you will be given instructions before your surgery date. Otherwise, it is important that you continue to take all your medications like you normally do. If you need to take medications during the day, bring them with you.
- Do not drink alcohol for 24 hours before surgery.
- Get a good night sleep.
- Shower and wash hair and face on the day of the surgery.
- Eat a normal breakfast. Bring a lunch or snack.
- Wear clothing that buttons in the front.
- Do not wear jewelry or makeup if surgery is to be performed on the face.
- Bring a friend or relative to keep you company and to assist you in getting home. A good book or magazine would also be helpful. Wifi is available in the waiting room.
The Day of Surgery
Shortly after you arrive, you will be taken to a treatment room where the doctor will review the risks and benefits of Mohs surgery with you and ask you to sign an informed consent form.
The area of the skin cancer will be cleaned, and a local anesthetic will be injected. The doctor will remove a thin layer of skin surrounding the cancer. Any bleeding will be stopped with an electric machine called a cautery, and a bandage will be applied. This initial process takes about 30 minutes. Following this, you will be able to relax while the tissue is processed. Preparing the tissue for microscopic examination and evaluation of the slides by the Mohs surgeon can take up to 90 minutes.
If microscopic examination reveals that tissue still contains cancer cells, the procedure is repeated in the areas where tumor cells were found. The goal is to remove all of the skin cancer and preserve the greatest amount of healthy tissue. Skin cancers can grow deeply and develop roots that extend beyond the area you can see. As a result, the size of the surgical incision depends on the extent of the tumor. Two or three surgical layers are common, but you may require more. These are performed on the same day.
Reconstruction Following Mohs Surgery
When it has been determined your skin cancer has been completely removed, your doctor will decide how best to manage your wound. In some cases, the wound is allowed to heal by itself (granulation). In other cases, the wound is repaired with side-to-side stitches, a skin graft, or a flap. The decision depends on the size and location of the wound. This is performed by the Mohs surgeon on the same day. In more extensive or aggressive skin cancers, you may be referred to a plastic surgeon or oculoplastic surgeon for reconstruction.
If your wound will heal by granulation, you will receive written instructions on changing the bandage. This must be done daily for three to six weeks.
While it is impossible to predict how long the procedure will take, Mohs surgery and reconstruction usually lasts several hours. Please plan on spending the day at our office, and do not make plans for later in the day.
After Your Surgery
- Pain: Most patients have only slight discomfort. If this occurs, take two Extra-Strength Tylenol® tablets every 4 hours. Continue to avoid compounds that contain aspirin, ibuprofen, and naproxen sodium because they may cause bleeding.
- Bleeding: Occasionally, bleeding follows surgery. If this happens, stay calm. Lie down and apply steady, firm pressure over the wound as close as possible to the bleeding area. Keep the pressure continuous for 20 minutes (timed). Do not lift the bandage to check on the bleeding. If bleeding persists after 20 minutes, apply steady pressure for an additional 20 minutes. If bleeding still continues, call the Dermatology Center at (716) 845-3378 and press option 4 to speak with a nurse. If it is after hours or on the weekend, call (716) 845-2300 and ask the operator to page the Dermatology provider on call.
- Swelling, Bruising: Swelling and bruising are common, particularly when surgery is performed near the eye. Usually, this is not a problem, and the swelling and bruising decrease as the wound heals.
- Drainage: All wounds drain during the first week or two, and frequent dressing changes are necessary.
- Infection: Wound infections are unusual. If you see thick, foul-smelling fluid coming from the wound, call the Dermatology Center at (716) 845-3378 and press option 4 to speak with a nurse. If it is after hours or on the weekend, call (716) 845-2300 and ask the operator to page the Dermatology provider on call. You may be asked to come to the clinic to be evaluated. An antibiotic may be necessary.
- Redness: All wounds develop a halo of redness that disappears gradually. If the area becomes very red and itchy, you may be allergic to the antibiotic ointment or the tape. If this develops, call the Dermatology Center at (716) 845-3378 and press option 4 to speak with a nurse.
- Scarring: Most surgeries leave a scar. The scar will improve and become less noticeable as time passes.
- Stitches, Skin Grafts: If your wound is closed with stitches or a skin graft, keep the area clean, bandaged as directed, and dry until the next clinic visit. If you see foul-smelling fluid coming from the wound, call the Dermatology Center immediately at (716) 845-3378 and press option 4 to speak with a nurse. If it is after hours or on the weekend, call (716) 845-2300 and ask the operator to page the Dermatology provider on call. You may be asked to come to clinic to be evaluated. An infection may be developing and an antibiotic may be necessary.
- Outside repair by a plastic surgeon or an oculoplastic surgeon: If you have questions or concerns related to a repair performed by another physician, those should be directed to their office as they will be able to better guide you on how to proceed.
General Postoperative Instructions
- Pain relievers containing acetaminophen (Tylenol®) may be taken.
- DO NOT drink alcohol (including wine and beer) for 24 hours before and 48 hours after surgery.
- NO bending, heavy lifting, or strenuous activity for one week after surgery. It is best to resume normal exercise after your stitches have been removed.
- NO aerobic exercise or weight lifting for two weeks after surgery.
After the Wound Has Healed
As the wound heals, some tightness and itching are common and usually lessen with time. Itching is often relieved by applying a small amount of plain petroleum jelly on the scar. Tumors often involve nerves, and it may be several months to a year before normal feeling returns. The area may remain numb permanently. Only time will tell.
Scar tissue that grows over the wound has many more blood vessels than the surrounding skin. The result is a red scar that may be sensitive to temperature changes. This sensitivity improves with time, and the redness gradually fades.
If the scar is unacceptable to you, surgical scar revision may be considered. Patients are advised to wait 12 months because the appearance of the scar will continue to improve for up to one year after surgery.
Defense Against Future Skin Cancer
The most important thing you can do to reduce your risk of future skin cancers is to protect your skin from further sun damage. This is easily achieved by reducing direct sun exposure and wearing a broad-brimmed hat and protective clothing, such as a long-sleeved sun protectant shirt. You should also apply broad spectrum sunscreen to all exposed skin, including the tops of the ears, 15 minutes before you go outdoors.
There are some excellent sunscreens available without a prescription. The sunscreen you chose should be broad spectrum and protect both against ultraviolet A and B rays of the sun and should have a sun protection factor (SPF) of at least 30 or higher. These colorless creams or lotions absorb or block the damaging rays of the sun that cause sunburn and other skin damage. They may wash off with water or heavy perspiration, so be sure to reapply sunscreen after swimming or exercise, and use a sunscreen labeled as water resistant. Be mindful of the fact that most sunscreens even with normal use need to be reapplied every 2 hours to provide the expected benefits.
Follow-up exams by your referring physician are important to help with early detection and treatment of any new skin cancer or the unlikely recurrence of the skin cancer already treated. As a person who has had a skin cancer, you are at increased risk of developing other skin cancers in the years ahead. You should be examined by your physician at least once each year and we recommended that you examine your own skin at monthly. If you notice suspicious areas on your skin between visits, check with your physician to see if a biopsy is needed.
How Can I Learn if I Am a Candidate for Mohs Surgery?
To schedule a consultation, please call our referral office at 716-845-3516.