What is Mohs surgery? (Also known as Mohs Micrographic Surgery)

The term "Mohs" refers to Dr. Frederic Mohs, Professor of Surgery at the University of Wisconsin, who developed this surgical technique in the early 1940s. The technique has undergone many refinements and has come to be known as "Mohs surgery" in honor of Dr. Mohs.

Dr. Mohs recognized that a skin cancer often resembles a "tip of the iceberg" with more tumor cells growing downward and outward into the skin, like the roots of a tree. These "roots" are not visible with the naked eye, but can be seen under a microscope.

Mohs Micrographic Surgery is a highly specialized and precise treatment for skin cancer in which the cancer is removed in stages, one tissue layer at a time. It is an outpatient procedure. The removal technique is no different than other procedures; however it is distinguished by a specific technique of tissue examination that is unique to Mohs surgery. Although some plastic surgeons and other specialists check excision margins, pathologic examination of the tissue is not the same as Mohs surgery.

Once a tissue layer is removed, the edges are marked with specially colored dyes, and a map of the specimen is created. The tissue is then processed onto microscope slides by a Mohs histotechnician. These slides are carefully examined under the microscope by the Mohs surgeon so that any microscopic roots of the cancer can be precisely identified and mapped. When cancer cells are seen, an additional tissue layer is removed only in areas where the cancer is still present, leaving normal skin intact. This saves as much normal, healthy skin as possible. Once the cancer has been removed, the Mohs surgeon will explain options for repair of the wound, including natural healing (granulation), stitching the wound together by a side to side closure, or using a skin flap or graft.

Mohs surgeons who are members of the American College of Mohs Surgery have undergone at least one year of fellowship training beyond dermatology residency, which allows for additional experience in all these specialized processes and techniques.

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