Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun. But this common form of cancer can also occur on areas of your skin not ordinarily exposed to sunlight.
Mohs surgery, also referred to as Mohs micrographic surgery (MMS), is a special technique that utilizes a both pathology and surgery to remove skin cancers in a physician’s office. Mohs is a very precise, highly detailed method whereby horizontal pieces of tissue are cut from the bottom-most layer layers of the skin tumor and immediately stained and examined under the microscope. Repeated saucer-shaped layers of tissue are removed and examined until no more skin cancer can be microscopically visualized in the sample.
Mohs surgery uses frozen sections of skin that are then stained with special dyes. The dyed frozen pieces of skin are examined under the microscope and a tumor map showing the sites of any residual cancer cells is drawn by the Mohs surgeon. The process permits an examination of the entire tumor’s margins simultaneously while the patient is waiting. If more cancer cells are seen under the microscope, tissue is removed at the site of involvement. Each skin layer that is removed is called a "level." If no more cancer cells are seen at a particular level, then it is deemed "clear" (no more tumor) and no additional levels are removed.
Mohs surgery is an improvement to standard surgery (local excision), which involves removing the visible cancer and a small margin of surrounding healthy tissue all at once. Mohs surgery allows surgeons to verify that all cancer cells have been removed at the time of surgery. This increases the chance of a cure and reduces the need for additional treatments or additional surgery.
The cure rate for Mohs Micrographic Surgery is the highest of all treatments for many skin cancers—often approaching 99 percent even if other forms of treatment have failed. This procedure - the most exact and precise method of tumor removal - minimizes the chance of regrowth and lessens the potential for scarring or disfigurement by conserving as much normal tissue as possible.
All surgical procedures have the potential for some degree of visible scarring. The appearance of a post-Mohs’ surgical scar will depend on several factors, including size and location of the final defect, individual skin characteristics and the reconstruction options available. Keep in mind, however, that the tissue-sparring nature of the Mohs’ technique may result in a smaller, less noticeable scar than other skin cancer removal methods.