Mohs Surgery

Mohs surgery, formally called Mohs micrographic surgery. removes skin cancer in stages. First, the visible cancer and a thin layer of surrounding tissue are removed. The tissue is carefully mapped, processed, and examined under a microscope. If cancer cells remain at an edge, the surgeon knows exactly where they are located. Another thin layer of tissue is then removed from that specific area.

This process is repeated until the examined margins are free of cancer. The goal is straightforward: completely remove the skin cancer while preserving as much healthy surrounding skin as possible.

Mohs surgery is most commonly used to treat the two most common types of skin cancer, basal cell carcinoma and squamous cell carcinoma. Mohs surgery may also be appropriate for certain less common skin cancers in which precise examination of the surgical margins is particularly important. However, not every skin cancer needs Mohs surgery. Many skin cancers can be successfully treated with standard surgical excision or other treatments.

The decision depends on the type of skin cancer as well as its location, size, microscopic features, and other risk factors. Mohs surgery may be recommended when a skin cancer:

• Occurs on the nose, eyelids, ears, lips, or other important areas of the face
• Is located in an area where preserving healthy tissue is particularly important
• Is large or has poorly defined borders
• Has an aggressive microscopic growth pattern
• Has previously been treated and returned
• Develops in an area previously treated with radiation
• Occurs in certain higher-risk locations
• Develops in a patient with a weakened immune system

Having a skin cancer on the face does not automatically mean that Mohs surgery is required. Your dermatologist considers the individual characteristics of the tumor when recommending treatment.

During a standard surgical excision, the skin cancer is removed with a predetermined margin of normal-appearing skin. The specimen is then sent to a laboratory for examination.

Mohs surgery takes a different approach. The surgeon examines the surgical margins during the procedure. If cancer remains, additional tissue is removed only from the area where tumor cells are still present. This provides two important advantages:

1. Mohs surgery offers exceptionally high cure rates for appropriately selected skin cancers. For many previously untreated basal cell and squamous cell carcinomas, cure rates can approach 99%.
2. Mohs surgery prioritizes not only the clearance of cancerous skin cells, but also preservation of healthy skin. Because additional tissue is removed only where cancer remains, Mohs surgery can preserve more normal skin. This is especially valuable on the nose, eyelids, ears, lips, and other areas where preserving even a small amount of healthy tissue may be important for both function and appearance.

Mohs surgery is generally performed in the office using local anesthesia. Patients remain awake and typically return home the same day. After the area is numbed, the surgeon removes the visible tumor and a thin layer of surrounding tissue. The tissue is then processed and examined under a microscope. During this time, the surgical area is temporarily bandaged and the patient waits comfortably in the office.

If cancer remains, the surgeon removes another thin layer specifically from the area where tumor cells were identified. This process continues until the examined margins are clear. Some cancers are completely removed with one stage, while others require several stages.

Once the margins are clear, the surgeon determines the best way for the area to heal. Depending on the size and location of the wound, this may include:

• Closing the area with stitches
• Allowing the wound to heal naturally
• Using nearby skin to create a flap
• Using a skin graft
• Coordinating reconstruction with another surgical specialist in select cases

The goal is to restore the area while achieving the best possible functional and cosmetic result.

Any surgery that removes skin will produce some degree of scarring. One advantage of Mohs surgery is that it removes the cancer while attempting to preserve as much healthy tissue as possible. A smaller surgical wound may make reconstruction easier and help minimize the final scar. Scars also improve significantly with time. A new scar may initially be pink, red, firm, or noticeable but typically fades and softens over the following months.

Although Mohs surgery offers very high cure rates, no treatment can guarantee that a skin cancer will never recur. It is also important to distinguish a recurrent cancer from an entirely new skin cancer. Patients who have developed one basal cell or squamous cell carcinoma are at increased risk of developing additional skin cancers in the future. A new cancer appearing elsewhere usually represents a separate tumor rather than spread of the original cancer. For this reason, regular full-body skin examinations remain important even after successful treatment.