Mohs surgery

Mohs is a special type of surgery that removes a tumour little by little, in layers, until no cancer remains. The goal is to remove the cancer and leave as much healthy tissue as possible.

Mohs surgery is also called Mohs micrographic surgery.

Mohs surgery may be used to treat different kinds of skin cancers, including basal cell carcinoma, squamous cell carcinoma, some types of melanoma and other rare types of skin cancer.

It is used to treat tumours:

• in areas where it is important to remove as little tissue as possible, such as the eyelids, ears, nose, lips, hairline, genitals, fingers or toes
• that are large (to leave a smaller scar)
• that have come back (recurred) or have a high risk of coming back
• in areas that have been treated with radiation therapy or where there is a scar
• that are growing quickly
• in people with immunosuppression
• with poorly defined edges (margins)

Mohs surgery is usually done as an outpatient procedure in a doctor’s office or hospital. This means that you don't stay overnight.

You are given an injection of medicine to freeze or numb the area (called a local anesthetic). You are awake for the procedure. The surgeon uses a surgical knife (scalpel) to remove the part of the tumour that can be seen along with a thin layer of surrounding tissue. A temporary bandage is placed on the cut (incision).

The tissue sample is taken to the lab to be looked at under a microscope to see if there are still cancer cells in the tissue.

If there is cancer in the tissue taken, another thin layer of tissue is removed and examined. Each round takes about an hour. The surgery takes 10 to 20 minutes, and looking at the tissue under the microscope takes 40 to 50 minutes.

These steps are repeated until the last tissue sample removed shows no cancer cells and there is a margin of healthy tissue around the sample.

The wound is repaired after all of the cancer is removed. Repairing the wound might include:

• leaving the wound to heal on its own
• closing the wound with stitches
• using a piece of skin from another area of the body to cover the wound (called a skin graft)
• seeing a surgeon to repair the area (if surgery was extensive)

Most wounds heal in 1 to 3 weeks. You should be able to return to most of your normal daily activities on the same day or the day after surgery. You will likely have to limit some activities, such as exercise or swimming, until you see your doctor for a follow-up appointment (usually 1 to 2 weeks after surgery).

You may have side effects after surgery, but everyone's experience is different. Tell your healthcare team if you have side effects that you think are from Mohs surgery. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Mohs surgery may cause these side effects:

• pain, tenderness or a burning sensation
• swelling
• bleeding
• bruising
• infection
• scarring
• nerve damage, such as numbness