Mohs Micrographic Surgery

Author: Allyson Distel, MPH
Last Reviewed: January 02, 2024

Mohs micrographic surgery was developed by Dr. Frederick Mohs in the 1930s. It is the most effective surgical treatment for removing some types of skin cancer, such as basal cell carcinoma and squamous cell carcinoma.

During this procedure, skin cancer is removed layer by layer. Each layer of tissue is looked at under a microscope until the margins are clear. Clear margins mean that the edges of the tissue removed are free of cancer cells when looked at under a microscope. Using a microscope gives your provider a precise way to remove cancerous tissue. It also helps spare more healthy tissue and prevents the need for more surgery.

Mohs surgery may cause less scarring as compared to other surgeries that remove skin cancer. The Mohs procedure is used to remove skin cancer in areas where preserving healthy tissue is needed for cosmetic and functional purposes (i.e. face, scalp, etc).

How is it done?

The Mohs procedure is often done as an outpatient, meaning that you don’t have to stay overnight at the hospital. The outpatient office will have a surgical area and a laboratory so that the tissue can be checked for cancer cells on-site. It is often done in one day.

These are the steps to the Mohs procedure:

  • The surgeon will look at the lesion and plan how much tissue will be removed. They may draw on your skin and take pictures. The goal is to remove the roots of the cancer to keep it from coming back (recurrence).
  • A local anesthetic is used to numb the skin and surgical area. Tell your provider if you are having pain.
  • The surgeon will remove the part of the tumor they can see with surgical tools.
  • Next, a deeper layer of skin is removed and cut into sections. Each section is color-coded with a dye that matches up with a mark left on the skin to show where each section of the skin was removed. A surgical site map will be drawn to track where each piece of the tissue came from.
  • A specialist will look at each part of the skin under a microscope for any cancer cells.
  • If cancer cells are found under the microscope, the surgeon will mark the location on the map and will remove another layer of tissue from that area of your skin.
  • Removal will continue until no cancer cells are seen from any removed sections of skin.
  • The surgeon will decide what type of reconstruction will be needed to heal the site. Some incisions will heal on their own, known as secondary-intention healing. A larger wound may be closed with stitches. An even larger wound may need a skin graft from another part of your body or a skin flap, which uses skin next to the Moh’s site to cover the wound. You may need to see a reconstructive surgeon if these options won’t close the wound.
  • You will be given time to rest, and you will be given instructions to follow at home.

It is normal to have some pain, bleeding, redness, and inflammation. Your provider will tell you how to manage these.

What will my care be like after the procedure?

Your provider will give you instructions about caring for your incision, which may be:

  • How to clean the surgical site and how to change the bandages (dressing).
  • Prescriptions and/or information about medications to use while your skin heals.
  • Timeline, such as when you can return to your normal activities.
  • Schedule for follow-up appointments to monitor healing and remove any stitches.
  • Instructions for treating the scar so that it heals and fades.

If you are having any new changes to your skin or if you have pain or bleeding that is not going away, call your provider.

American College of Mohs Surgery. Found at:

Skin Cancer Foundation. Mohs Surgery. Found at:

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