What Is Mohs Micrographic Surgery?
Mohs surgery is the most effective method for treating common forms of skin cancer like basal and squamous cell carcinoma, in addition to less common cancers. It has a very high cure rate of up to 96 to 99 percent, even when other forms of treatment have failed. Mohs surgery is named in honor of Frederick Mohs, MD, who developed the technique in the 1940s. The surgery is performed under local anesthesia in our outpatient clinic by our Mohs surgeons: Mary Maloney, MD, David Geist, MD, Dori Goldberg, MD, and Mark Scharf, MD.
There are three main parts to the procedure:
- First, your surgeon will surgically remove the tumor.
- Second, the tumor is processed in our lab and the margins are evaluated. If there is any tumor left, an additional "stage" or sample is taken and margins are checked again. By repeating this process in "stages," your Mohs surgeon can trace out the tumor and remove all areas of skin cancer while preserving as much healthy skin as possible. This ensures that no cancer is left behind.
- Third, once the tumor is removed, your Mohs surgeon will repair your skin with as little mark or scar as possible.
What Does the Surgery Involve?
The Mohs surgery team taking care of you consists of your Mohs surgeon, assisted by our Mohs fellow (a dermatologist who is in fellowship training for Mohs surgery) or our dermatology-certified nurse practitioner, a surgical nurse or medical assistant, and a histotechnologist, who processes the tissue and takes photographs for your medical record. Mohs surgery is performed in "stages" with about 20 to 40 minutes of wait time between each stage.
Getting Checked In
You will be brought into the surgery room where your blood pressure, pulse and medical history are checked and photographs are taken. We will review the Mohs procedure with you, answer your questions and have you sign a permission form.
Taking the First Stage
The area is cleaned with an antiseptic solution. A local anesthetic called lidocaine is injected to numb the area. The local anesthetic is the only part of the surgery that is uncomfortable. You will notice a stinging or burning sensation that lasts for a few seconds.
Once the area is numb, the tumor is removed with a thin rim of surrounding skin. The small of amount of bleeding is stopped with a cautery device that seals off little blood vessels. A temporary dressing is applied while you wait for the tissue processing. If a friend or relative has accompanied you, he/she can now return to the room to keep you company.
The removed skin is divided into pieces and carefully mapped to keep track of orientation, like on a clock face. By doing this, we are able to pinpoint the exact location of any remaining tumor detected during microscopic examination. The preparation and review of your slides takes approximately 20 to 40 minutes.
Additional Stages
If more cancer is found, the area is cleaned again and additional anesthetic is injected to ensure your comfort. A second stage of Mohs surgery is performed, removing only tissue at the area with remaining cancer. The average tumor requires two to four stages for removal. Do not be discouraged if your cancer is not removed in one stage. We are tracing the extent of the tumor very carefully, thereby removing as little normal tissue as possible. Only by removing small layers in stages can this be accomplished.
Repairing the Area: What Happens After the Cancer Is Removed?
After the cancer is removed, an open wound remains. The reconstruction and healing of the wound is a key component of Mohs surgery. Your Mohs surgeon has special training in facial reconstruction. The method chosen to repair your wound depends on its size, shape and location. Your Mohs surgeon will discuss the repair options with you, with attention to providing the best functional and cosmetic result.
Most often, the area will be repaired on the day of surgery using stitches. In some cases a skin graft (skin borrowed from another area) or skin flap (skin moved into the wound from a neighboring site) is used to provide the best result. Sometimes the wound is allowed to heal without stitches if this option will provide equal or better results. Once the area is repaired, you will go home with a large, bulky bandage (a "pressure dressing") that will remain in place for 24 to 48 hours. This helps reduce the risks of bleeding and infection.