Skin cancer is the most common type of cancer. When skin cancer is found early, it is often removed using procedures performed in a dermatologist’s office, such as scraping, freezing, or surgically removing it by excising the cancerous area. If the skin cancer is in a highly visible area of the body such as the face, your dermatologist may recommend Mohs surgery. Here, find out what this surgery is, why you might need it, and how to prepare and recover after the procedure.

What is Mohs surgery?

Mohs surgery is a precise surgery used to remove skin cancer. It is named after Dr. Frederic E. Mohs, the surgeon who invented the technique in the 1930s.

During Mohs surgery, the surgeon removes cancerous cells in a series of layers while preserving as much healthy skin as possible. This results in minimal scarring. Mohs surgery is different from a biopsy to detect skin cancer or an excision to remove skin cancer in which the tissue sample is often sent away to a separate laboratory for testing. Rather, during Mohs surgery, the surgeon checks to ensure all the skin cancer cells are removed throughout the procedure.

When performing Mohs surgery, the surgeon first removes the visible portion of the skin cancer. Then, the surgeon removes a deeper layer of skin and examines it under the microscope. If there are any remaining cancer cells, the surgeon may remove another layer of skin and, again, examine it under the microscope. This is done until no skin cancer cells remain. The surgeon may also do reconstruction around the tumor site to repair the wound and reduce scarring.

“Mohs surgery is a precise surgical technique for skin cancer removal on sensitive anatomical sites like the lip and ear while preserving as much normal skin as possible and maintaining the normal anatomy of the site.” – Shadmehr (Shawn) Demehri, MD, PhD, associate professor at the Center for Cancer Immunology and Cutaneous Biology Research Center at Massachusetts General Hospital/Harvard Medical School and the 2023 Cancer.Net Specialty Editor for Hereditary Skin Cancer Related Syndromes

Why might I need Mohs surgery?

Mohs surgery can be used if you have basal or squamous cell carcinoma or melanoma. It may be used for other, specific conditions. Mohs surgery is often recommended if the skin cancer is located on a highly visible part of your body, such as your:

  • Head

  • Neck

  • Face

  • Scalp

  • Ears

  • Lips

  • Fingers

Mohs surgery can also be used on other parts of the body depending on how aggressive the cancer is, its size, and whether it has recurred following previous treatment.

There is a higher rate of fully removing the cancer with Mohs surgery than with other techniques. It can cure up to 99% of skin cancer that has not been treated before and 94% of skin cancer that has recurred after previous treatment, according to the Skin Cancer Foundation.

What can I expect before and during Mohs surgery?

Typically, Mohs surgery occurs in an outpatient setting like a dermatology office. Dermatologists can receive specialized training in Mohs surgery as part of a fellowship program with the American College of Mohs Surgery (ACMS). You can find one of these specialists near you on the ACMS website.

Before Mohs surgery, the doctor’s office will provide you with specific instructions about preparing for your surgery. Commonly, this may include stopping certain medications such as over-the-counter pain relievers, avoiding smoking, and avoiding certain foods or beverages before the procedure, according to the ACMS. Be sure to ask your doctor’s office about any instructions that are unclear.

Mohs surgery can take several hours, so you will need to clear your calendar for the day of the procedure. During your procedure, the surgeon will use local anesthesia to numb the affected area. You will be awake during the entire procedure. 

After removing the first layer of skin, the surgeon will put a bandage on the site, and you will go to a waiting room while a technician and the surgeon examine the sample under a microscope. Then, the surgeon will tell you whether they need to take another layer of skin or if all the skin cancer cells were removed in the first layer. Most tumors require 1 to 3 stages to remove all of the cancer cells, according to the ACMS.

What will recovery be like after Mohs surgery?

Depending on the wound created by the procedure, the doctor may need to use stitches, skin glue, or a skin graft to repair the area after Mohs surgery. Some wounds may also heal on their own without additional repair. 

Your surgeon’s office will send you home with detailed instructions about how to care for your wound, as well as medications that are safe to take for pain or swelling. These instructions may also include whether you need to refrain from exercising or doing other physical activity for a certain period of time. After surgery, you will also schedule a follow-up appointment if you need to have your stitches removed or if your doctor would like to monitor your healing.

Mohs surgery is highly effective at removing skin cancer, but people who have had skin cancer in the past are more likely to have it again in the future. Therefore, it is important for people who have been treated for skin cancer to see their dermatologist regularly to monitor for any possible new skin cancers.