Mohs micrographic surgery is considered the most effective technique for treating many basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), the two most common types of skin cancer. The procedure is done in stages, including lab work, while the patient waits. This allows the removal of all cancerous cells for the highest cure rate while sparing healthy tissue and leaving the smallest possible scar. Mohs surgery is performed by doctors who are specially trained to fulfill three roles:

1. As the surgeon who removes the cancerous tissue,
2. As the dermatopathologist who analyzes the lab specimens, and
3. As the surgeon who closes or reconstructs the wound.

Mohs surgery is the gold standard for treating many basal cell carcinomas (BCCs) and squamous cell  carcinomas (SCCs), including those in cosmetically and functionally important areas around the eyes, nose, lips, ears, scalp, fingers, toes or genitals. Mohs is also recommended for BCCs or SCCs that are large, aggressive or growing rapidly, that have indistinct edges, or have recurred after previous treatment. Some surgeons are also successfully using Mohs surgery on certain cases of melanoma.

• Step 1: The Mohs Surgeon injects a local anesthesia, which numbs the area completely. The patient stays awake throughout the procedure.
• Step 2: Using a scalpel, the Mohs surgeon removes a thin layer of visible cancerous tissue. Some skin cancers may be “the tip of the iceberg,” meaning they have roots or extensions that aren’t visible from the surface. The lab analysis, which comes next, will determine that. Your wound is bandaged temporarily and you can relax while the lab work begins.
• Step 3: The Mohs surgeon cuts the tissue into sections, color codes them with dyes and draws a map of the surgical site. In the lab, a dermatopathologist freezes the divided tissue, then cuts very thin horizontal slices like a layer cake. The slices are placed on microscope slides, stained and covered. This meticulous process takes time.
• Step 4: Using a microscope, the Mohs surgeon examines all the edges and underside of the tissue on the slides and, if any cancer cells remain, marks their location on the map. The surgeon then lets you know whether you need another layer of tissue removed.
• Step 5: Back in the operating room, the Mohs surgeon injects more anesthesia if needed and removes another layer of skin, precisely where the cancer cells remain, based on the map. Then, while you wait, the lab work begins again. This entire process is repeated as many times as needed until there are no more cancer cells.
• Step 6: The procedure is done in stages, all in one visit, while the patient waits between each stage. After removing a layer of tissue, the dermatopathologist examines it under a microscope in an on-site lab. If any cancer cells remain, the surgeon knows the exact area where they are and removes another layer of tissue from that precise location, while sparing as much healthy tissue as possible. The surgeon repeats this process until no cancer cells remain.
• Step 7: Once the site is clear of all cancer cells, the wound may be left open to heal or the Mohs surgeon may close it with stitches. This depends on its size and location. In some cases, a wound may need reconstruction with a skin flap, where neighboring tissue is moved into the wound, or possibly a skin graft. In some cases, your Mohs surgeon may coordinate the repair of your wound with another specialist such as a plastic surgeon, oculoplastic surgeon or hand surgeon. In most instances, however, the Mohs surgeon will repair the wound immediately after obtaining clear margins.

If more than one or two rounds are needed, the entire process can take up to several hours, so be prepared for that. It’s worth it, though, because this precise technique has the highest cure rate of any treatment method and can save the greatest amount of healthy tissue, leaving the smallest scar possible. Carefully follow Dr. Papadopoulos or Dr. Kim’s instructions for wound care, scar care, and follow-up to achieve the best outcome.

Each patient is unique; therefore, results of treatment may vary.

Q: How does Mohs surgery work?

A: Once the affected area is numbed with a local anesthetic, the visible tumor and a thin layer of surrounding tissue known as the safety margin will be removed. The tissue is taken immediately to our in-house laboratory where it is processed and examined under a microscope. If no evidence of skin cancer exists, the procedure is completed. If the tissue tests positive for skin cancer, the precise location is marked and the physician removes another layer from the area where the cancer was detected. The same process is repeated until the doctor reaches a cancer-free layer.

Q: How long does the procedure take?

A: Each layer may take 30 to 60 minutes to process. As a result, Mohs surgery requires patience by both the patient and the physician. Patients should plan to spend half a day at our office.

Q: For what types of skin cancer is Mohs surgery recommended as a treatment?

A: Basal cell carcinomas, squamous cell carcinomas and lentigo maligna melanomas are the cancers most commonly treated by Mohs surgery. Less common tumors treated by Mohs surgery include adnexal neoplasms (including desmoplastic trichoepitheliomas), atypical fibroxanthomas, merkel cell carcinoma and dermatofibrosarcoma protuberans (DFSP).

Q: If Mohs surgery has a 99% cure rate, why isn’t it used to treat all skin cancers?

A: There are certain and specific criteria that justify the utilization of Mohs surgery to treat a skin cancer. Our physicians will evaluate your specific case and suggest the treatment that is most appropriate.

Additional information on skin cancer and Mohs surgery:

• American College of Mohs Surgery
• American Academy of Dermatology
• American Society for Dermatologic Surgery