What you can expect

Mohs surgery is done on an outpatient basis in an operating room or procedure room that has a nearby laboratory that allows the surgeon to examine the tissue after it's removed.

In most cases, the procedure lasts a few hours. But since it can be difficult to tell how extensive a skin tumor is 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 anesthetic numbs the skin, so you won't feel any discomfort during the procedure.

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 for analysis. This portion of the procedure typically takes the longest amount of time.

Expect to wait about an hour or so in a waiting room for the surgeon to return. It may help to bring a book or magazine to pass the time. You'll be able to use the restroom or have a snack, if you need to, but you won't be able to leave the surgeon's office until the procedure is complete.

While you're waiting, the surgeon or technician cuts the tissue sample into sections and examines them with a microscope. Your surgeon takes great care to keep track of the exact spot where each piece of tissue was removed by making a map. That way, if a small area of cancer is found in one piece of tissue, the surgeon knows precisely where to continue with the surgery.

If cancer remains, your Mohs surgery will continue. Your surgeon removes an additional layer of tissue from the affected area, taking care to remove tissue that contains cancer while leaving as much healthy tissue as possible intact. Again, you'll wait while the surgeon examines the tissue in the laboratory.

The process is 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 (healing by second intention)
  • Using stitches to close the wound (primary closure)
  • Shifting skin from an adjacent area (skin flap) to cover the wound
  • Using a skin graft from another part of the body, such as behind the ear, to cover the wound

If the surgical area is extensive or complex, your surgeon may temporarily close your wound and then refer you to another surgeon for reconstructive surgery to repair the wound.

Sept. 06, 2017
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  5. Squamous cell skin cancer. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed July 28, 2017.
  6. Basal cell skin cancer. Fort Washington, Pa.: National Comprehensive Cancer Network. http://www.nccn.org/professionals/physician_gls/f_guidelines.asp. Accessed July 28, 2017.
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