What Is Mohs Surgery?

The Mohs procedure was developed to allow a dermatologic surgeon to perform surgery on skin cancer and have a greater certainty that the tumor has been completely removed. Mohs surgeons are Board Certified Dermatologists who have undergone additional training in the Mohs surgery technique.

Skin cancers grow like icebergs; there is more below the surface than can be seen on the skin surface. If only the visible tumor is removed cancer cells can get left behind. With Mohs surgery, we cut around the cancer and examine all edges under the microscope to make sure all of the abnormal cells are removed. If remaining cancer is seen, we will remove additional skin but only from the area with the cancer. In this way, the surgeon will remove all remaining tumor while leaving the normal intact. Mohs surgery provides a 99% cure rate for most skin cancers. It has the lowest recurrence rates, highest cure rates, and best cosmetic results of any skin cancer treatment currently available.

Most patients undergoing Mohs surgery have a common type of skin cancer, basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). Mohs is usually recommended when a BCC or SCC is aggressive or large, appears in an area with little tissue beneath it (i.e. eyelid, nose, ear, scalp, genitals hand, or foot), or was treated and skin cancer has returned. There are some other rare forms of skin cancer where Mohs may also be indicated. The diagram below shows the process of Mohs surgery:

Mohs Surgery Process

Pre-Op Instructions

  • You may eat a normal breakfast on the morning of surgery. If your surgery is in the afternoon, please eat lunch.
  • We recommend you have a support person drive you to and from the office. They may remain with you during most of the day. There will be only short periods where your support person will be asked to wait in the waiting room.
  • Please do not bring children to the office.
  • If you are a smoker, try to stop smoking 1 week before surgery and for 2 weeks afterward as smoking impedes healing.
  • If the procedure will be on your face please come with a clean face and do not wear make-up.
  • Wear loose comfortable clothing.

What To Expect On The Day Of Surgery

Please arrive 15 minutes before your appointment. Be prepared to spend the entire day with us as we cannot predict how long your surgery will take. You are welcome to have a friend or family member come to your appointment with you.

  1. After checking in, our nurse or medical assistant will take you to one of the procedure rooms and review your medical history, current medications, and allergies.
  2. You will be asked to sign a consent form that will give us your permission to perform the procedure and take photographs.
  3. We will take a close-up photograph of the area where the procedure will be performed.
  4. Your skin will be cleansed with alcohol and then numbed with an injection of Lidocaine anesthetic. This may burn and sting for a few seconds, but the area will become numb quickly. We will take every step to make the procedure as painless as possible.
  5. The first step of Mohs surgery is to try to determine the extent of the tumor under the skin. This is typically done using a curette, an instrument used to scrape the skin. The tumor cells will come away while the normal skin stays intact.
  6. Then the first layer of skin is removed with a scalpel; any bleeding is stopped.
  7. The nurse or medical assistant will bandage the wound and we will show you back to the waiting room or have you wait in your surgery room.
  8. The removed tissue is taken to our lab to be processed and will be looked at under the microscope to see if the cancer is removed. This process takes approximately 90 minutes.
    • When the tissue is ready, the doctor examines it under the microscope. If there is any tumor remaining we will mark that area on a map. We use the map to tell us where the tumor remains on your skin.
    • Back in the procedure room, we will remove the dressing and inject more local anesthetic (Lidocaine). The doctor will excise additional skin from the area where the cancer is still present; the process is then repeated as above.
    • The average number of these stages that need to be taken is two.
    • Once the cancer is completely removed we will take another photograph of the wound and discuss the repair.

What To Expect Post-Op

We will explain the methods of closure with you which we think will give the best result. Once wounds are healed and the stitches taken out, the scar will continue to heal and develop over the next 6-12 months. Sometimes a second procedure is needed to help the scar be less noticeable. This is typically done between 4 to 8 weeks after the surgery. This can include injections of anti-scarring medication or laser procedures.

After the wound is closed, we will make you an appointment to be seen for follow-up, if necessary. You will have a bandage in place. We will give you detailed written post-op care instructions and phone numbers to call if you have questions or concerns. To give yourself the best chance of healing well we strongly advise you to follow the written wound care instructions. Typically, most wounds are not painful after surgery. If there is discomfort you may take an
acetaminophen. Your referring doctor will receive a letter and surgery notes from Dr. Hajar.

Mohs Surgery FAQ