Health Library Explorer
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A-Z Listings Contact Us

Understanding Mohs Surgery

Mohs surgery is done to help treat skin cancer. It's named for Dr. Frederic Moh, who developed it in the 1930s. This surgery is done in stages.

During the surgery, a very thin layer of the tumor and a small area around it are removed. The removed tissue is looked at right away under a microscope. The process is then repeated in the exact place where cancer cells are still seen. Layers of tissue are removed and checked under a microscope until no more cancer cells are found.

During standard, non-Mohs surgery, the tumor and a margin or edge of healthy tissue around it are removed all at once. Mohs surgery very slowly and precisely removes the tumor in layers that are examined right away. This makes it more likely that all the cancer is removed. It also lowers the chance of it coming back. Mohs surgery lets the doctor to remove less healthy tissue than with standard tumor removal. This means there's less scarring.

Why Mohs surgery is done

Mohs surgery is most often used for skin cancer that's:

  • Large or fast-growing

  • Likely to spread

  • Likely to come back, or has come back

  • On an area where it's important to remove as little tissue as possible (like the nose, lips, ears, eyelids, or hands)

  • Borders or edges aren't clear

How Mohs surgery is done

The surgery is most often done in an office or surgery center. It's an outpatient procedure. This means you go home after the surgery is done. The surgery can take up to 4 hours or even longer. During the surgery:

  • You might change into a patient gown or stay in your regular clothes. You'll be positioned so that the doctor can see and get to the treatment area.

  • The area to be treated might be marked with a pen.

  • A drape or cover is put over the area and a bright light is used to see it.

  • You will stay awake during this surgery. A tiny needle is used to put numbing medicine into the area around the tumor. This keeps you from feeling pain during the surgery.

  • A sharp knife, called a scalpel, is used to remove the first layer of tissue. The area is covered with a small bandage.

  • You might stay in the procedure room or move to a waiting area.

  • The tissue is examined in a lab to see if and where cancer cells might be left. This can take up to an hour or longer. During this time, you can read or watch TV.

  • When you return to the surgical room, more numbing medicine is injected, if needed. Then more of the tumor is removed and checked in the lab.

This process is repeated until the removed tissue shows no more cancer cells. Once the tumor is totally removed, you and your surgeon can decide how best to repair the surgery site. The repair may be done right away or it may be scheduled for another day.

Risks of Mohs surgery

  • Bleeding

  • Infection at the surgery site

  • Nerve damage

  • Pain

  • Problems with reconstruction

  • Rarely, the skin cancer comes back and more treatment is needed

  • Reopening of the incision after surgery

  • Scarring

  • Severe bruising

Online Medical Reviewer: Kimberly Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: Lu Cunningham RN BSN
Online Medical Reviewer: Michael Lehrer MD
Date Last Reviewed: 8/1/2019
© 2000-2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.