Mohs surgery is a specialized technique which removes skin cancers in a very systematic and logical manner. It achieves the highest cure rate and leaves the smallest possible area to reconstruct after the skin cancer has been removed. The basic principle behind the Mohs’ technique is to remove the entire skin cancer without taking any more normal skin than is absolutely necessary. As SkinCare Physicians’ Mohs surgeon, Dr. Thomas Rohrer likes to say, it removes the skin cancer, the whole skin cancer, and nothing but the skin cancer. Here is your brief guide to Mohs surgery: what it is and why it has become the treatment of choice for non-melanoma skin cancers located in cosmetically sensitive areas.
Microscopically controlled surgery was developed by Dr. Frederick Mohs as a more precise way to remove skin cancers. Originally, chemicals were applied to the skin cancer and the entire surgical procedure could take several days. The technique has been refined over the years to the point where the skin cancer is now removed and examined under the microscope for any remaining tumor almost immediately.
Frequently, what can be seen on the skin surface only represents a part of the actual skin cancer, “the tip of the iceberg” so to speak. We cannot see the “roots” of the skin cancer that are under the skin surface. Instead of guessing approximately how far these “roots” extend under and around the skin cancer, the microscope is used to trace out and map the exact extent of the tumor. The surgeon may then remove only the cancerous tissue. This prevents either removing too little or leaving tumor behind to come back or recur (usually larger) in the future, or from removing too much, and creating a larger than necessary wound. In essence, the best of both worlds is achieved with this technique. The entire skin cancer is removed and as much as possible of the normal skin is preserved. The Mohs’ microscopically controlled technique offers a cure rate of 98 – 99%, the highest of any technique available.
When a patient comes in for Mohs surgery, the skin cancer is marked with a sterile surgical marking pen and the area is numbed up with a local anesthetic. Next, a small one or two millimeter margin is taken around the visibly obvious skin cancer. The tissue is marked like a clock for orientation, stained, and then examined under the microscope. In Mohs surgery, unlike standard excision, the entire periphery and base of the removed area is examined. This gives complete surgical margin control and is the key to the high cure rate of Mohs surgery. If any skin cancer is seen at any of the margins, it is marked on a map. In this manner, the exact location of any residual tumor may be determined and then removed, without having to remove any of the skin that appeared normal under the microscope. This process is repeated until all of the margins are clear. Sometimes this occurs on the first go around, other times it may take many passes to clear the tumor. It is this process of systematically searching out and removing all of the “roots” of the skin cancer that gives Mohs’ surgery its cure rate of 98-99%. When the margins are determined to be clear, the wound is repaired. All of this occurs in the same day.
Since Mohs surgery requires highly trained personnel, and can be time consuming, it is reserved only for certain cases. The most common indications for using the Mohs’ technique are as follows:
SkinCare Physicians has two exceptional Mohs surgeons, Dr. Thomas Rohrer and Dr. Karen Kim. Both of our Mohs surgeons have gone through a rigorous fellowship training in Mohs surgery and are members of the American College of Mohs Surgery. If you have any questions about Mohs surgery please schedule an appointment to discuss it with Dr. Rohrer or Dr. Kim or visit our Mohs surgery procedure page.