What Is Mohs

What Is Mohs Micrographic Surgery?

Mohs micrographic surgery is a highly specialized procedure for the removal of skin cancer. It was originally developed in the 1930’s by Dr. Frederick Mohs. It is used to treat many types of skin cancer. Skin cancer begins in the uppermost layer of the skin, grows downward, and spreads horizontally along the surface of the skin. Unfortunately, it’s extensions cannot be directly seen without the use of a microscope. Therefore, what is apparent to the naked eye on the surface of the skin may be only the “tip of the iceberg”.


There are three surgical steps to Mohs micrographic surgery:

      • the surgical removal of the visible portion of skin cancer with excision or scraping
      • the surgical removal of a thin layer of tissue at the bed of the cancer, and
      • examination of all of the excised tissue under the microscope.


You can see a video about this procedure to the right of the page.

By examining all of the edges and the complete underside of the tissue, the physician is able to trace out and exactly locate any remaining areas of cancer. Before the tissue is examined, it is marked with colored dyes to distinguish top from bottom and right from left, and a detailed map of the excised tissue is made. By doing this, the surgeon is able to pinpoint the exact location of any remaining tumor during the microscopic examination. The map allows the surgeon to return precisely to that spot to remove additional tissue. Thus, only the area of remaining cancer is removed. The procedure is continued until no cancer remains at the edge.

The major drawback of Mohs micrographic surgery is that it is very laborious and time consuming, requiring specialized training, support personnel and equipment. Consequently, only a few physicians are capable of providing this type of therapy.


Advantages of Mohs Micrographic Surgery

Using Mohs microscopic examination, the Mohs micrographic surgeon pinpoints areas involved in cancer and selectively removes only those areas. In this way, the skin cancer is traced out to its “roots”. This results in the highest chance for cure while preserving as much normal tissue as possible. Using the Mohs micrographic surgery technique, the percentage of success is very high, usually 97% to 99%, even when other forms of treatment have failed. With this technique, an outstanding cure rate is achieved, without needless removal of adjacent healthy tissue.