Updated March 16, 2026

Mohs surgery is a highly specialized technique for treating skin cancer. Johns Hopkins dermatologic surgeon Elise Ng, M.D., explains the procedure.

What is Mohs surgery?

Mohs surgery is a method for treating skin cancers, particularly those on the face and neck. During this procedure, the surgeon removes layers of skin surrounding the skin cancer. One layer at a time is taken and examined under a microscope until all of the cancer is removed, leaving behind as much healthy skin as possible.

How effective is Mohs surgery?

Mohs surgery is highly effective, with cure rates of up to 99% for many common skin cancers. This is because the technique allows the edges of the skin cancer to be evaluated more thoroughly than traditional skin cancer surgery techniques. As a result, Mohs surgery is considered the gold standard treatment for high-risk skin cancers, such as those that are large, located in sensitive areas such as the head and neck, or have aggressive growth patterns.

Why is Mohs surgery performed?

Mohs surgery can treat:

• Basal cell carcinoma
• Squamous cell carcinoma
• Certain types of melanoma (such as lentigo maligna)
• Other rare skin cancers

Your doctor may choose this method to address skin cancer that is:

• Large
• Aggressive (i.e., the cells show an infiltrative growth pattern)
• Located in a sensitive area where saving healthy skin is important (head, neck, fingers, toes or genitals)
• Occurring in patients with a weakened immune system (i.e., organ transplant or lymphoma)
• Recurrent after a previous treatment

How is Mohs surgery performed?

The Mohs procedure takes place in an outpatient setting. The surgeon uses a local anesthetic to numb the area completely. After injecting the anesthetic, the surgeon uses a scalpel to remove thin, saucer-shaped layers of skin in a sequential manner.

After each layer of tissue is removed, the specimen is processed in the lab by a Mohs histotechnician, a lab specialist who is specially trained in preparing slides of skin samples for microscopic examination. This process typically takes up to one hour.

The Mohs surgeon then examines the slides under the microscope to assess the extent of the skin cancer and identify microscopic roots. If tumor cells remain at any of the margins, an additional tissue layer is removed corresponding to the area where cancer remains.

Some cancers appear small on the surface but have extensive growth several skin layers below. Other cancers may be small and shallow and require removal of only a few small layers. The procedure continues until the tissue is cancer-free, which helps preserve the maximum amount of surrounding healthy skin.

Once the margins are determined to be clear of tumor, the Mohs surgeon discusses and performs reconstruction of the wound. This occurs in the same surgical suite as the Mohs surgery.

What is recovery like for Mohs surgery?

You may have some mild discomfort or pain for about a week after surgery. Most patients require only over-the-counter pain medications. Depending on how much skin was removed, you may also need to wear a bandage until the skin in that area recovers. Your doctor will provide instructions for care at home.

What are the benefits of Mohs surgery?

• Mohs surgery provides the highest cure rate (up to 99%).
• The technique provides the most thorough evaluation of tumor margins and spares as much healthy surrounding skin as possible. This helps minimize the scarring.
• The procedure is performed under local anesthesia while the patient is awake so there are no medication or food restrictions.

What are the risks of Mohs surgery?

• It is a low-risk procedure with a low rate of complications. Some risks include:
• Scarring
• Larger wound than expected
• Bleeding
• Infection
• Loss of muscle function or feeling in the area (temporary or permanent)
• Recurrence of skin cancer

Medically reviewed by Elise Ng, M.D.