Mohs surgery

Definition

Mohs surgery, also known as Mohs micrographic surgery, is a precise surgical technique for removing several types of skin cancers. During Mohs surgery, layers of cancer-containing skin are progressively removed and examined until only cancer-free tissue remains.

When performed by an experienced surgeon, Mohs surgery offers maximum removal of cancer with minimum damage to surrounding healthy tissue. Mohs surgery is usually done on an outpatient basis using a local anesthetic.

Mohs surgery is often cited as having the highest cure rate for the most common type of skin cancer, basal cell carcinoma. It's also highly effective for recurrent basal cell carcinoma and offers the highest cure rate for these cancers, as well.

Why it's done

Mohs surgery is used to treat the most common skin cancers, basal cell carcinoma and squamous cell carcinoma, as well as some kinds of melanoma and other more unusual skin cancers. Mohs surgery is especially useful for skin cancers that:

• Have a high risk of recurrence or that have recurred after previous treatment
• Are located in areas where you want to preserve as much healthy tissue as possible, such as the eyes, ears, nose, mouth, hairline, hands, feet and genitals
• Have borders that are hard to define
• Are large or aggressive

Risks

As with any surgical procedure, Mohs surgery carries the risk of:

• Bleeding
• Pain or tenderness around the surgical site
• Infection

Your surgeon may recommend pain relievers after the procedure to help manage any postoperative pain. Infection is uncommon but can usually be treated with oral antibiotics.

Other complications that may result from Mohs surgery are uncommon but may include:

• Temporary or permanent numbness surrounding the surgical area, if small nerve endings are cut
• Temporary or permanent weakness of the surgical area, if the tumor is large and a muscle nerve is severed
• Itching or shooting pain in the affected area

Select your doctor carefully
Doctors who specialize in Mohs surgery have training in dermatology, dermatologic surgery and dermatopathology — the microscopic study of skin diseases — as well as in the techniques of Mohs surgery. Mohs surgery can be technically challenging, and it takes several months of training before an acceptable skill level is achieved.

When choosing a Mohs surgeon, make sure that the surgeon has completed a one-year fellowship training period, endorsed by the American College of Mohs Surgery (ACMS). The ACMS has an online tool on its website to help you find a Mohs surgeon near you.

How you prepare

Let your surgeon know of any medications or supplements you're taking, including any blood-thinning medications, such as warfarin (Coumadin), clopidogrel (Plavix), or aspirin. Some supplements — vitamin E, ginkgo, ginger, ephedra and others — may affect your chances of bleeding after surgery, so make sure your surgeon knows about those, too. Continue taking any prescription medications as instructed unless your surgeon tells you otherwise.

In most cases, only local anesthetic is used, so typically there aren't any restrictions on what you can eat or drink before the procedure. Wear comfortable clothing. Because there's some waiting time during the procedure, you may wish to bring a snack and a book or magazine to help pass the time. Depending on the extent of the surgery, you may want to have someone drive you home after the procedure.

What you can expect

Mohs surgery is done on an outpatient basis, usually at your surgeon's office. Typically, a Mohs surgeon's office has its own dermatologic surgery suite and a laboratory for immediate examination of tissue.

In most cases, the procedure lasts about four hours. But since it can be difficult to tell how extensive a skin tumor's "roots" are just by looking at its surface, doctors often advise reserving the whole day for the procedure.

You likely won't have to change into a surgical gown unless the location of the tumor requires it. To prepare you for surgery, your surgeon or a nurse cleanses the area to be operated on, outlines it with a special pen and injects the area with a local anesthetic. The injection may pinch or sting a bit at first, but numbness usually sets in quickly. If you're especially anxious, oral sedatives may be available.

During the procedure
Once the anesthetic has taken effect, your surgeon uses a scalpel to remove the visible portion of the cancer along with a thin, underlying layer of tissue that's slightly larger than the visible tumor. A temporary bandage is placed on your incision. This takes only a few minutes.

The surgeon then takes this tissue to the laboratory, where it's prepared for examination under a microscope. This portion of the procedure typically takes the longest amount of time, about an hour or so.

In the lab, the surgeon or a technician cuts the tissue sample into sections and marks them to reflect their geographical orientation. These sections are then diagrammed on a specially prepared map of the surgical area (Mohs map). The sections are frozen and cut into very thin slices to be placed on slides and stained.

Next, your surgeon examines the slides under a microscope for evidence of additional cancer. If cancer remains, your surgeon notes its location on the Mohs map and uses the map as a guide to remove an additional layer of tissue from your skin, taking care to remove tissue that contains cancer while leaving as much healthy tissue as possible intact.

The steps outlined above are repeated until the last tissue sample removed is cancer-free. Local anesthetic can be re-administered as necessary.

After the procedure
After all of the cancer has been removed, you and your surgeon can decide on how to repair the wound. Depending on the extent of the operation, this might include:

• Letting the wound heal on its own
• Using stitches to close the wound
• Using a skin graft from another part of the body, such as behind the ear, to cover the wound
• Shifting skin from an adjacent area (skin flap) to cover the wound

If the surgical area is extensive or complex, your surgeon may refer you to a plastic surgeon for reconstruction.

Results

One of the advantages of Mohs surgery is that you know your results right away and you usually don't leave your appointment until you're free of the skin tumor in question.

Your surgeon or referring doctor will want to monitor your recovery to make sure your wound is healing properly. After that, regular follow-up visits are important to catch any recurrence of cancer or new skin cancers as early as possible.