What Is Mohs Surgery?

Here’s what to know about when you might need this surgery and what’s involved before, during, and after the procedure.

• Large
• Aggressive
• Resistant to previous treatments or at a high risk of recurring
• Located in a sensitive area, such as your face, head, neck, hands, feet, and genitals

A dermatologist with extensive training on the technique usually performs Mohs surgery.

Typically, you remain awake during the procedure. The surgeon numbs the surgical area with local anesthesia injections so you won’t feel pain.

“There is no way to know in advance how many stages will need to be performed during Mohs surgery,” says Kimberly Brady, MD, a dermatologist at the Roswell Park Comprehensive Cancer Center in Buffalo, New York. “Each case is different, and the number of stages depends on how far the cancer has spread beyond what can be seen with the naked eye. Sometimes a tumor will be cleared in one stage, and other times it will take multiple stages. Since it typically takes about an hour to process and examine each stage, the surgery can last anywhere from two to several hours.”

Before your surgery, tell the doctor about all the medications and supplements you take, especially ones that thin your blood or make you bleed more. You may have to stop taking these medications for a time before your procedure.

Unless your healthcare professional instructs you otherwise, you can typically eat as usual before your procedure.

Because it’s impossible to know how long Mohs surgery will take, you should clear your schedule for the whole day. You may want to bring a book or tablet to help pass the time while the surgeon examines the tissue samples and you wait for the results.

Mohs surgery is usually performed at an outpatient surgery center or doctor’s office that has a laboratory nearby.

During the procedure, you shouldn’t feel any pain, due to the local anesthetic, but you might feel pressure. If you need additional layers of skin removed, you may receive more injections of anesthesia to help keep you comfortable.

While doctors analyze the tissue layers for cancer, you’ll stay in a waiting room. During this time, you can use the restroom, have a snack, or read — but you can’t leave until your procedure is complete because the surgeon may need to close the wound.

• Linear Repair The doctor makes a side-to-side closure.
• Skin Graft The doctor uses a small piece of skin from another part of the body.
• Flap The doctor slides adjacent skin to cover the area.

Shorter-term risks could include slow wound healing, too much bleeding, and infection. Call your doctor right away if you experience any of the following:

• Bleeding that doesn’t stop
• Severe pain that worsens or doesn’t go away after a few days
• A fever
• A thick, yellowish discharge that smells foul
• Red, hot, or swollen skin around the wound

Longer-term risks following Mohs surgery are rare but may include a temporary or permanent loss of nerve function.

• Details about when to change bandages and how to clean the surgical site
• Information about prescription medications or over-the-counter pills or topical ointments
• A schedule of follow-up appointments to remove any stitches and monitor your healing
• Recommendations for treating your Mohs surgery scar to ensure that it heals and fades quickly
• A timeline for when you can return to certain activities, such as wearing makeup or exercising, depending on the location of your surgical site

Postprocedure healing depends on the type of wound, the location of the surgery, and the repair that you have.

“Areas like the face are often quicker to heal than areas like the lower leg, for example,” says Karen L. Connolly, MD, a dermatologist and Mohs surgeon at Memorial Sloan Kettering Cancer Center in Basking Ridge, New Jersey. “The healing process can take anywhere from weeks to months. It can take up to a year for a scar to have its final appearance.”

Other potential complications include the following:

• A reaction to the local anesthetic, which may include irritation at the injection site or a rapid heartbeat
• Slow wound healing or excessive bleeding
• Bruising or swelling
• Pain or tenderness
• Scarring
• Tumor regrowth
• Numbness or weakness in the surgical area, which can be temporary or permanent

Your surgeon will come up with a schedule of postsurgical and ongoing checkups. It’s also important to learn the signs of skin cancer so you can contact your doctor if you notice anything that looks irregular.

Depending on the extent of the skin cancer, some people who have Mohs surgery will also require reconstructive surgery. This can often be done immediately after the Mohs procedure.

Reconstructive surgery is usually a consideration if the cancer leaves a large scar or is located in a sensitive area, such as the nose, eyes, and ears.

Healing will depend on the type of reconstruction performed after Mohs surgery, says Brady: “All surgeries will leave a scar, but that scar should fade over time so that it is not noticeable long term. Most of the time, cosmetic procedures will not be needed to improve the appearance of the scar, but a patient can always discuss their concerns with their surgeon."

• Scraping away the top layer of the scar, called dermabrasion
• Laser treatments
• Cryotherapy, which is when a doctor freezes and destroys scar tissue

Your doctor can work with you to determine whether this type of procedure is necessary or which method may work best for your Mohs surgery scar.

• Mohs surgery is the gold standard for removing skin cancers such as basal cell carcinoma and squamous cell carcinoma.
• During the procedure, a doctor removes and analyzes thin layers of skin to detect cancer cells. They precisely remove skin layers until no cancer remains.
• Scars from Mohs surgery can take a year or more to fully heal. If necessary or desired, you can ask your doctor about procedures that may help you get a more cosmetically pleasing result.