What is Mohs Micrographic Surgery?

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Mohs micrographic surgery was developed in the 1930’s by Dr. Frederic Mohs. The technique differs from others due to the physician being the cancer surgeon, pathologist, and reconstructive surgeon. Since its development, Mohs surgery has been refined into the most precise and advanced treatment for skin cancer, yielding success rates up to 99%. Mohs surgery is so effective because it evaluates the tissue surrounding the cancer more thoroughly than traditional skin cancer surgery techniques. 

Mohs surgery is used to treat the most common skin cancers, basal cell carcinoma and squamous cell carcinoma, some types of melanomas, and other forms of skin cancer. Mohs surgery is especially useful for skin cancers that:

• Have a high risk of recurrence or that have recurred after previous treatment

• Located in areas where you want to preserve as much healthy tissue as possible, such as        

        around the eyes, ears, nose, mouth, hands, feet, and genitals

• Have borders that are hard to define

• On a patient with a suppressed immune system due to an organ transplant, lymphoma, or  

        other cause

• Are large or aggressive

Mohs surgery takes place in an outpatient setting with the surgeon using a local anesthetic to numb the area completely. During surgery, thin layers of cancer-containing skin are progressively removed and examined until only cancer-free tissue remains. The goal is to remove as much of the skin cancer as possible, while doing minimal damage to surrounding healthy tissue. Mapping is a critical part of the process, as it helps the surgeon plan the removal of each layer. The surgeon marks areas of the removed skin samples with colored dyes and makes a map of the surgical area using a freehand drawing or a computer application. The map provides a guide to the surgical area and aids the surgeon in identifying where cancerous cells are still being found. Some cancers are deeply rooted in lower levels of the skin, appearing small on the surface but with extensive growth several skin layers below. Other cancers may be shallow and require removal of only a few small layers. After each layer of tissue is removed and sliced into very thin sections it is then examined under the microscope. The microscope is used to assess the extent of the skin cancer and identify microscopic roots. If tumor cells remain at any of the margins, the map is used to remove an additional tissue layer precisely at the area where cancer remains. This continues until the tissue is cancer-free, which spares the maximum amount of healthy surrounding tissue.

The surgeon will decide how to repair the wound and provide care instructions. 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

This may include a topical ointment, medication, or special care instructions to reduce the risk of infection. You might also experience some mild pain and soreness after your surgery. Expect to wear a bandage over the wound for a week or longer. Though exactly how long you'll need depends on your situation. 

One of the advantages of Mohs surgery is that you know your results right away. Typically, you don't leave your appointment until all of the skin cancer has been removed.