Mohs Micrographic Surgery
In the 1930s, Dr. Frederick Mohs conceived of a method of removing skin cancers where essentially 100% of the margin could be evaluated. Over many years, the method (which has come to be known as “Mohs micrographic surgery”) has gained popularity due to its high cure rate, tissue sparing nature, and the usual one-day nature of the procedure. After using local anesthesia, the visible portion of the cancer is removed with a small margin of normal tissue surrounding it. This tissue is then placed on a flat surface where it is cut into enough pieces so that the sides of the tissue can lie in the same plane as the deep margin. It is then mapped and dyed for orientation.
The tissue then is frozen, sliced, and placed on a microscope slide. This way, all of the margins may be examined to make sure the cancer is out. If any part of the tumor remains behind, it will show through the margin and it will be seen on the microscope slide. Because of the orienting and mapping, the exact location of any persistent tumor is known. This tells the surgeon specifically where to go to retrieve more tissue. Instead of taking a large margin of unnecessary tissue, only a small piece is removed where the tumor persisted. This all saves the patient an unnecessarily large defect, and because the margins are essentially 100 percent evaluated, the cure rates are extremely high. The tumor defect is not repaired until it is known that the surgical margins are clear of the cancer. This adds to the convenience of the Mohs procedure because it usually saves the patient from having to return for an additional surgery on another day.
Mohs surgery is used today for the most common types of skin cancer, basal cell carcinoma and squamous cell carcinoma, but may also be used for the more uncommon types like leiomyosarcoma, dermatofibroscaroma protuberans, atypical fibroxanthoma, sebaceous carcinoma, etc. As surgeons with the highest level of Mohs surgical training, Drs. Willis and Sewell follow these applications of Mohs surgery micrographic surgery as well as a modified version for superficial melanomas (the in situ type) as well.