Question: I’ve heard so much about the high cure rates for Mohs surgery in treating nonmelanoma skin cancers. Why isn’t Mohs surgery popular for malignant melanoma?
Answer: The answer to that question has to do with how normal-looking skin appears on the slide that’s prepared during the Mohs surgery. Mohs surgery uses frozen sections to identify abnormal cancer cells. Frozen sections work very well in distinguishing nonmelanoma skin tumors. However, malignant melanoma is different. A frozen section of normal, healthy skin as prepared for Mohs can appear to have melanoma. This is due to the background visual “noise” caused by melanocytes. Melanocytes are melanin-producing cells located in the skin that become melanoma when they are atypical. The frozen section used by Mohs surgeons cannot differentiate very well between cancerous and noncancerous melanocytes. Again, remember that with Mohs surgery, the margin is so narrow that there is absolutely no room for error. This need for accuracy is especially poignant for malignant melanoma because this cancer is so deadly.
Research is underway to overcome this obstacle. There are special stains that are being developed that can be used with the Mohs frozen sections. Some surgeons have used these stains in clinical practice to help differentiate between malignant melanocytes and those associated with normal skin color.
In my experience, we can use Mohs surgery for malignant melanoma. However, it’s only possible by developing a very special technique that is not at all intuitive even for members of the American College of Mohs Surgery (ACMS). There is a learning curve. I think it’s absolutely accurate and fair to say that Mohs for malignant melanoma can be done effectively by certain physicians who do it a lot and are well known. But this technique hasn’t been done for very long. Using Mohs surgery for melanoma is a hot button at the ACMS. There are some people who believe in it and some who feel that we need more data to ensure that the long-term cure rates are acceptable. The future of Mohs for melanoma is promising, but it’s not the standard of care right now.