Mohs Surgery: How It's Done and What to Expect

Medically Reviewed By Raechele Cochran Gathers, MD
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Mohs surgery is a highly effective treatment of skin cancer. It limits the size of scars because it preserves healthy tissue. As a result, Mohs surgery is a common method of removing skin cancer on the face, ears, and neck. Mohs surgery can treat basal cell carcinoma, melanoma, and squamous cell carcinoma, as long as the cancers have not spread beyond the skin.

This article will explain Mohs surgery in detail, including how it works and differs from traditional skin cancer surgery. It will also describe what to expect before, during, and after Mohs surgery, along with typical results.

How Mohs surgery works

gloved hands holding magnifying camera to examine woman's skin on shoulder and neck area
Irina Efremova/Stocksy United

The technical name for Mohs surgery is “Mohs micrographic surgery.” The procedure involves removing skin tissue one thin layer at a time and examining the fresh tissue under a microscope. This continues until the final tissue layer is free of cancerous cells. 

Dr. Frederick Mohs developed the surgical technique in the 1930s and refined it in the 1950s. However, it was not until the 1960s that dermatologists began using it as a way to remove skin cancer. The technique became common practice in the 1980s.

With other methods of skin cancer surgery, surgeons cut away a significant portion of skin around the cancer to ensure they remove all of it. This leaves only healthy tissue behind — a “clean margin.” It can also leave a significant scar.

With Mohs surgery, the surgeon examines individual layers of the tissue under a microscope for signs of cancer. The microscope magnifies the tissue. The surgeon marks the regions where cancer cells are present. With this information in hand, the surgeon returns to the patient and removes additional tissue. These steps continue until the team sees a clean margin.

Mohs surgery requires special training to perform it with skill and reassurance. If you are having Mohs surgery, ask your surgeon about their training and results with Mohs surgery.

The purpose of Mohs surgery

Your doctor may recommend Mohs surgery to treat cancerous skin conditions, especially those that occur in visible areas, such as the nose, cheeks, ears, chin, and neck. Mohs surgery can treat the following types of skin cancer: 

Reasons your doctor may recommend Mohs surgery include:

  • It has not spread to your lymph nodes or other areas.
  • It is located near scar tissue.
  • It is large or growing rapidly.
  • It is an aggressive type of skin cancer, meaning it has a greater chance of spreading.
  • The edges are hard to define.
  • You are an organ transplant or lymphoma patient.
  • You have skin cancer on your face, neck, hand, or other visible areas.
  • Your skin cancer has recurred after other treatments or is likely to recur.

What to expect the day of Mohs surgery

Mohs surgery is an outpatient procedure under local anesthesia in a doctor’s office or clinic. You will be awake during the procedure. The surgery can take from 1 hour to several hours depending on the size and type of skin cancer. Plan for an entire day at the clinic unless your doctor tells you otherwise. Mohs surgery generally includes these steps:

  1. Your doctor will inject a local anesthetic to numb the surgical area. You may also receive a sedative.
  2. Your doctor will remove the visible tumor along with a thin layer of surrounding tissue.
  3. Your team prepares the tissue and examines it under a microscope.
  4. If cancer is present in the tissue, your doctor will take another layer of tissue and examine it. This continues until your doctor finds a cancer-free layer.
  5. Your team will bandage or dress the wound.

Your dermatologist or a plastic surgeon will close the wound, either in the same clinic or another location. You may have reconstructive surgery the same day or another day to repair the area.

Mohs surgery preparation

Mohs surgery involves only minor preparation. Steps to take include:

  • Answering all questions about your medical history: This includes prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.
  • Stopping smoking as soon as possible: Even quitting for just a few days can be beneficial and help the healing process.
  • Taking or stopping medications exactly as directed: This may include not taking aspirin, ibuprofen (Advil, Motrin), and blood thinners.

For your comfort, bring water, snacks, and something you can do while you wait for the surgery to begin and during the surgery itself. There will be times when you wait in a room while the doctor examines the layers of skin tissue.

Questions to ask your doctor

Preparing for Mohs surgery can be a little stressful. Contact your doctor with concerns and questions before surgery and between appointments. You may want to bring a list of questions to your appointment. Questions can include:

  • Will Mohs surgery cure my skin cancer?
  • How much do you charge for Mohs surgery compared to other removal methods?
  • How much scarring will I have after the procedure?
  • Should I consult a plastic surgeon for closing the wound?
  • How long will the procedure take? When can I go home?
  • What restrictions will I have after the procedure? When can I return to work and other activities?
  • What assistance will I need at home?
  • How should I take my medications?
  • How will you treat my pain?
  • When should I follow up with you?
  • How should I contact you during and after regular office hours?

Potential complications of Mohs surgery

Complications after Mohs surgery are not common, according to a 2013 study. The most common problems include:

  • infection
  • bleeding and hematoma
  • poor wound healing

The study’s authors note that most instances of bleeding and poor wound healing were in patients taking medicines that inhibit blood clotting, which is essential to stop bleeding and promote healing. Adverse events were more common in people with a history of smoking.

You can reduce the chance of these adverse events by telling your doctor and all members of your care team about all medications you take. Also inform them of allergies to medications, including sedatives and anesthetics. If you smoke, try to avoid smoking in the weeks leading up to and after your surgery.

What to expect after Mohs surgery

Knowing what to expect after Mohs surgery can help you get back to your everyday activities. Here are answers to frequently asked questions about Mohs surgery:

How will I feel after Mohs surgery?

You may have swelling, bruising, and minor pain after Mohs surgery. Your doctor may recommend applying ice packs to help with swelling and bruising. Pain after Mohs surgery usually responds to over-the-counter pain medicines. Take them as your doctor recommends.

Does Mohs surgery leave a scar?

Because the doctor keeps removing tissue until all cancer is gone, it is difficult to know in advance how large the resulting wound will be. However, the step-by-step approach allows doctors to remove the smallest amount of tissue possible.

If surgery leaves a gap, the surgeon will repair it by transplanting a piece of healthy skin from another area of the body. Either way, most patients will have a smaller scar with Mohs surgery than they might have with other treatment options.  

Still, ask your surgeon what you should expect with scarring after your Mohs surgery. Sometimes the wound and resulting scar are larger than the patient expects. That is because skin cancer often goes deeper and farther than the lesion you see on your skin. Remember that the doctor’s goal is to remove all of the cancer while minimizing scarring.

Scars shrink and fade with time. Some redness and bumpiness at the incision are typical in the first 6 weeks after surgery. The appearance of Mohs surgery scars continues to improve over several months, but it may take a year or so for the scar to fully mature. 

How can I minimize scarring?

Proper wound care can minimize scarring after Mohs surgery. Follow your doctor’s instructions regarding wound care, which may include some of these tips:

  • Apply an ice pack to your wound for 10–20 minutes each hour while awake for the first 48 hours after Mohs surgery. This helps reduce postoperative swelling and bruising.
  • Apply ointment to the wound during dressing changes (or daily), as moist wounds typically heal faster than dry wounds and have less scarring.
  • Limit your physical activity for about a week to avoid movement that might stretch your wound.
  • Stop or pause smoking, if you smoke, until your wound heals.

Ask your doctor about other scar reduction methods as well as treatment options for reducing scars that have already formed. Treatment may include keeping a silicone gel or patch over the scar to decrease the thickness of the resulting scar.

Most scars take up to a year to fully heal, and some may take longer. If you are unhappy with your scar after this period, consider scar revision surgery.

When can I go home?

You should be able to go home right after your Mohs surgery. Your doctor may recommend avoiding strenuous activity or exercise for up to 7 days in order for your wound to heal. You may need to return to your doctor to get your sutures out after 7–10 days.

When should I call my doctor?

It is important to keep your follow-up appointments after Mohs surgery. Contact your doctor for questions and concerns between appointments. Call your doctor right away or seek immediate medical care if you:

  • are bleeding more than expected
  • have a fever
  • experience pain that your pain medicine cannot relieve
  • have unexpected drainage, pus, redness, or swelling of your incision

Outlook

Many organizations note the high cure rate of Mohs surgery. It cures up to 99% of skin cancers that have not been previously treated, according to the American College of Mohs Surgery. This is higher than with other skin cancer surgeries. Mohs surgery can also reduce the amount of scarring compared to other methods of skin cancer removal.

Summary

Mohs surgery is a successful and low risk method of removing skin cancer, including melanoma. It involves removing cancerous skin tissue layer by layer and examining it under a microscope for signs of cancer. The surgeon repeats the process until there are no signs of cancer in the tissue.

Mohs surgery has a high cure rate, low complication rate, and involves minimal preparation. It can take longer than other forms of skin surgery. However, it minimizes scarring, so it can be beneficial for exposed or sensitive parts of the body. This includes the face, ears, scalp, and genitals.

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Medical Reviewer: Raechele Cochran Gathers, MD
Last Review Date: 2022 Feb 20
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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