Skin Cancer Services: Mohs Surgery

The Mohs surgical process involves repeated stages of surgical excisions followed by microscopic examination of the skin tissue removed in order to assess whether any tumor cells remain. Each stage can take about an hour.

Some skin cancers that appear small on clinical exam may extend over a larger area beneath normal-appearing skin. For that reason, it is impossible to predict in advance the number of stages necessary or the time required to adequately treat the tumor. Because Mohs surgery is generally used to treat complex skin cancers, about half of all Mohs-treated tumors require two or more stages for complete excision.

View a video of a Mohs microsurgery procedure ›

Step 1: Anesthetic

The area around the skin cancer is numbed with a local anesthetic.

Step 2: Stage I removal of visible tumor 

Once the skin has been completely numbed, the tumor is gently scraped with a curette, a semi-sharp, scoop-shaped instrument. This helps the surgeon define the tumor’s margins before the first thin, saucer-shaped layer of tissue is surgically removed. A needle heated by an electric current may be used to stop any bleeding at the excision site.

Step 3: Mapping the tumor 

Once the first layer of tissue has been removed, it is marked, or mapped, so that its orientation to surrounding skin is noted, labeled and color-coded. This helps the surgeon determine the precise location of the tumor and its margins at each stage of the mapping process. Testing of the tissue can take about 45 minutes to an hour, so the wound is bandaged temporarily.

Step 4: Additional staging

If any section of excised tissue is found to have cancer cells at the margins of the tumor, the surgeon then removes another thin layer of tissue from the precise area where the cancer cells were detected. The newly excised tissue is again mapped, color-coded, processed and examined. If microscopic analysis still shows evidence of disease, the process continues layer by layer until the cancer is completely removed.

By beginning early in the morning, Mohs surgery is generally finished in one day. Sometimes, however, a tumor may be extensive enough to necessitate a second day.

Step 5: Reconstruction

The tissue in the area of the excised tumor is reconstructed to preserve normal function and maximize aesthetics. The best method of repairing a wound can be determined only after the cancer is completely removed. Reconstruction may involve stitches, a skin graft or a flap, or the wound may be allowed to heal naturally.

Stitches are often used to close a wound created by the removal of a small lesion. This procedure speeds healing and can often have good cosmetic results. For example, a small, thin scar can be hidden in an existing wrinkle line.

Skin grafts involve covering the site of the excision with skin taken from another area of the body. There are three types of skin grafts. The first is called a split-thickness graft. This is a thin layer of skin, usually taken from the thigh. This graft can be either a permanent coverage or temporary coverage before another cosmetic procedure is done at a later date. The second graft-type is the full-thickness graft. This involves stitching a thicker layer of skin, usually taken from behind the ear or around the collarbone (the donor site) over a wound. The donor area is then sutured to provide a good cosmetic result. A third type of graft uses skin and cartilage. This tissue usually is taken from the ear in order to repair defects of the nose.

Healing by spontaneous granulation involves letting the wound heal by itself naturally. This offers a good chance to observe the wound repair itself after removal of a difficult tumor. Experience has taught us that there are certain areas of the body where nature will heal a wound as nicely as any further surgical procedures. Sometimes, a wound is allowed to heal with the understanding that a resulting scar may be unacceptable and require some form of cosmetic surgery at a later date.

In rare cases, when Mohs surgery is extensive or when removal of the tumor results in functional impairment, we may recommend that you visit one of several consultant surgeons for reconstruction.

Learn more about our skin cancer team and the services we offer. To make an appointment, please call 949-824-0606.