Mohs Skin Cancer Surgery

Mohs Surgery is a specialized form of skin cancer surgery used to treat several forms of skin cancer.  It is a major medical procedure, but is safely performed in the office setting.

The Mohs Micrographic Surgical Procedure

Mohs Surgery is a specialized form of skin cancer surgery used to treat several forms of skin cancer.The area of skin being treated is marked and the Mohs Surgeon removes small sections of skin and examines them under the microscope while the surgery is being performed.  If there are any cancerous skin cells identified, the Moh’s Surgeon will remove more tissue until all cancerous tissue is removed.

How is Mohs micrographic skin cancer surgery performed?

The procedure originally involved the application of a chemical on the skin. It has been revised and refined since then, eliminating the need for the chemical fixative and maintaining the microscopically controlled excision.

Today, there are three separate steps to the “fresh tissue technique.”

  1. Curettage of the visible part of the skin cancer
  2. Surgical removal (or excision) to a certain depth of the tissue
  3. Examination under the microscope

Before this tissue is examined, it is marked with colored dyes to distinguish top from bottom and right from left. By doing this, we are able to pinpoint the exact location of any remaining tumor during the microscopic examination. If more cancer is found, the procedure is repeated, but only in the area of the remaining cancer.

How long does Mohs skin cancer surgery take?

It is usually completed in a day. Total removal of a skin cancer may involve several surgical sessions of a few hours duration. Then the wound created by the surgery is managed.

How effective is Mohs surgery in the treatment of skin cancer?

The Mohs technique has a high success rate – as often as 97 percent to 99 percent effective, even if other forms of treatment have failed. But even with such an excellent chance of cure, no one can guarantee 100 percent.

What are the advantages of Mohs surgery?

Using microscopic examination, the Mohs surgeon can pinpoint areas involving cancer and selectively remove tissues only from those areas. In this way, the cancer is traced to its roots. This results in the removal of as little normal tissue as possible and the highest chance of cure. Other forms of therapy frequently have only a 50 percent to 70 percent chance of success in curing skin cancers that have had previously unsuccessful treatment.

Will the surgery leave a scar?

Yes. Any form of therapy will leave a scar. However, the Mohs procedure tends to minimize this as much as possible.

Will my insurance reimburse me for Mohs surgery?

Some health insurance policies cover the total cost. Most cover at least part of it. Each policy is different. Please check with our office manager if you have any questions regarding costs and insurance forms.

What happens at the pre-operative consultation?

The physician takes the opportunity to examine your skin cancer, take a pertinent history and determine whether the Mohs technique is the most suitable form of treatment. It also helps you learn about the procedure. Every skin cancer is different, and because of the high demand for Mohs treatment, careful scheduling is necessary. A suitable date for surgery that is mutually acceptable will be arranged. Patients may be photographed before any treatment (usually at the initial visit), as well as immediately after surgery, and after healing. These photographs become part of your medical record and may be used for teaching purposes.

Will I need to be hospitalized after skin cancer surgery?

Probably not. Whenever possible, the surgery is performed as an outpatient procedure, but occasionally we require that the patient stay in the hospital. We will inform you if we feel it would be best for you to be hospitalized.

How should I prepare myself for Mohs surgery?

Get a good night’s rest and eat a light breakfast. It you are taking any medication, take it as usual unless we direct otherwise. It is a good idea to bring a book or magazine with you on the day of surgery. The procedure may take a full day, much of which you will spend in the waiting room.

How many sessions of Mohs surgery will I need?

This depends entirely upon how deep or extensive your skin cancer is. Unfortunately, there is no way to determine this prior to surgery.

How long does the surgery take?

Each step (or stage) of the surgical procedure takes about 10 to 15 minutes. Following surgery, it usually takes at least an hour for the slides to be prepared for the microscopic examination. Several surgical stages and microscopic examinations may be required.

Should someone come with me on the day of surgery?

It may be pleasant to have company while sitting in the waiting room. And it is recommended that you have someone drive you home.

Does skin cancer surgery hurt?

We use a local anesthetic, usually Xylocaine, to first numb the skin. Be sure to inform the surgeon if you experience anything more than a slight discomfort.

What happens on the day of the surgery?

After the local anesthetic is given, the surgeon removes a thin layer of skin involved with the cancer. The bleeding may be stopped with a cauterizing machine that generates heat. Before you leave the surgical suite, the nurse will dress your wound. The removed tissue is sent to the laboratory for microscopic examination. It usually takes at least an hour to prepare the slides, although sometimes it may take somewhat longer.
If examination of the slide(s) reveals your tissue still contains cancer cells, the procedure will be repeated as soon as possible. Several surgical excisions and microscopic examinations may have to be done in one day, and occasionally it is necessary to have the patient return in subsequent days for additional surgery.

How many surgical sessions are there?

The average is two or three sessions, so most patients are finished after several hours. Light snacks may be eaten. No alcoholic beverages, please.

Will I have pain after surgery?

Most patients do not. If you are uncomfortable, we recommend taking two Tylenols every four hours. Avoid aspirin-containing compounds such as Anacin or Bufferin as these may produce bleeding.

What about bleeding after surgery?

Bleeding rarely occurs following surgery. If this should happen, lie down and place steady, firm pressure over the bandage as close as possible to the area that is oozing blood. Apply pressure continuously for 20 minutes. Do not lift the bandage to check the bleeding. If the bleeding persists after 20 minutes of steady pressure, repeat pressure for another 20 minutes or go the nearest hospital emergency room.

What are other possible complications?

All wounds develop a small halo of redness that gradually disappears. Severe itching with extensive redness may indicate a reaction to adhesive tape. You should call our office if this develops.Swelling is common following Mohs surgery, particularly when it is performed around the eyes. All wounds show a moderate amount of swelling. This is usually not a problem. We usually insist on frequent dressing changes because all wounds normally drain. Lifting and aerobic exercise is prohibited one to four weeks after surgery.

What is the next step after completion of the Mohs surgery?

When the skin cancer has been completely removed, a decision is made on what to do about the resulting wound. There are three usual choices:

  1. To close the wound with stitches
  2. To cover the wound with a skin graft or flap
  3. To let the wound heal by itself

What happens if the wound can be closed immediately with sutures or a skin graft?

If we close the wound with sutures or place a graft, keep it clean and dry until your next visit. If you detect a foul-smelling fluid in that area, call our office immediately. This may mean that the wound has become infected and an antibiotic may be necessary.

What happens if the wound is allowed to heal by itself?

If the wound is allowed to heal by itself (or granulate in), the dressing must be changed every day until healing is complete. All wounds normally drain, and dressings are changed twice daily to rid the drainage. The nurses will instruct you on how to change the dressing.

How long will the wound take to heal by itself?

It usually heals in four to eight weeks. When healing is well advanced, you can stop the daily dressing changes.

What happens after the wound has healed?

You may experience a sensation of tightness (or drawing), but this is normal. After several months, you will feel this less and less. Frequently tumors involve nerves, and it may take up to a year or so before feeling returns to normal, or near normal. Sometimes the area stays numb permanently. Only time will tell. The new skin that grows over the wound-contains many more blood vessels than the skin that was removed. This results in a red scar and the area may be sensitive to temperature changes (such as cold air). This sensitivity improves with time, and the redness gradually fades. However, if you are having discomfort, try to avoid extremes of temperature. Patients frequently experience itching after their wounds have healed because the new skin does not contain as many oil glands as previously existed. Plain petroleum jelly will help relieve the itching.

Once the wound has healed, how often must I return for a follow-up?

A follow-up by a dermatologist for at least five years is essential. After the wound has healed, our practice is to have patients return to their referring physicians for yearly visits.Should there be a recurrence of the skin cancer after Mohs surgery, it may be detected at once and treated. Experience has shown that if there is a recurrence, it usually will be within the first year following surgery. Studies have shown that once you develop a skin cancer, there is a possibility that you will develop others in the years ahead. We recommend that you be seen at least once a year for the rest of your life by your dermatologist so that he or she may determine whether you have developed any new skin cancers. Importantly, if you notice any suspicious areas, it is best to check with your referring physician to see if a biopsy is indicated.

Must I avoid the sun after skin cancer surgery?

No, not entirely. We do not think that sunshine will be harmful as long as you provide yourself with adequate protection, avoid burning, and use discretion.Sunlight is a main contributing factor in the development of skin cancer, and patients who have developed one skin cancer often will develop more at a later time. Therefore, in the future, when you go into the sun, we recommend that you liberally apply sunscreen with a sun protection factor of at least 15 to all exposed areas, including the tops of ears.In addition to sunscreen, a broad-brimmed hat and protective clothing will further guard you from the sun. Yes, you can lead a normal lifestyle – if you take precautions. Remember, an ounce of prevention is worth a pound of cure.

Pre-Surgery Instructions

  • No aspirin products (Aspirin, Advil, Motrin, Celebrex, etc.) for 10 days prior to procedure. You may take Tylenol if necessary. Coumadin or other blood thinning medications should be stopped 72 hours prior to your surgery day. PLEASE CHECK WITH YOUR PRESCRIBING DOCTOR BEFORE STOPPING ANY MEDICATIONS.
  • No alcohol consumption one week prior to procedure.
  • The Mohs procedure may take the entire day. Please plan accordingly.
  • We encourage you to eat a good breakfast that morning.
  • Please dress comfortably and wear older clothes. We do not require you to wear a gown during the procedure and there is a risk of drips and spills.
  • You may bring books, iPods, and laptops to use privately in the waiting area between procedures.
  • If a graft is necessary, you will need to be available to come back the following day for your first dressing change.


A Mohs Surgeon has received extensive training in the procedure, and will involve other physicians in the treatment process such as a plastic or reconstructive surgeon and pathologist to ensure the best cosmetic outcome.