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Mohs Micrographic Surgery


Developed by Frederic E. Mohs, M.D., in the 1930s, the Mohs micrographic surgical procedure has been refined and perfected for more than half a century. Initially, Dr. Mohs removed tumors with a chemo surgical technique. Over the course of a number of days, thin layers of tissue were excised and frozen before being pathologically examined. He developed a unique technique of color-coding excised specimens and created a mapping process to accurately identify the location of remaining cancerous cells. As the process evolved, surgeons refined the technique and now excise the tumor, remove layers of tissue and examine the fresh tissue immediately. The normal treatment time has now been reduced to one visit and allows for immediate reconstruction of the wound. The heart of the procedure -- the color-coded mapping of excised specimens and their thorough microscopic examination -- remains the definitive part of Mohs micrographic surgery.

Clinical studies have shown that the cure rate for Mohs micrographic surgery is the highest of all treatments for skin cancer -- up to 99 percent, even if other forms of treatment have failed -- and 95 percent even if the skin cancer has been previously treated. It relies on the accuracy of a microscope to trace and ensure removal of skin cancer down to its roots. This procedure allows dermatologists, trained in Mohs surgery, to see beyond the visible disease, and to precisely identify and remove the entire tumor, leaving healthy tissue intact unharmed. Mohs surgery is most often used in treating two of the most common forms of skin cancer: basal cell carcinoma and squamous cell carcinoma.


Because the precise mapping procedure requires more time and expertise than a standard excision, it is not performed on all skin cancers. Your doctor may recommend Mohs micrographic surgery if your cancer is recurrent, large or located on a cosmetically delicate area such as your face such as the nose, ear, lips, and eyelids where it is critical to limit the amount of tissue removed for the best cosmetic result. The technique is also used for tumors with poorly defined borders and ‘roots’ that invade surrounding tissue. Mohs surgery is indicated when:

  • The cancer was treated previously and recurred
  • The cancer is in a sensitive area such as the face where it is important to preserve  as much healthy tissue as possible
  • the cancer is large
  • the edges of the cancer cannot be clearly seen
  • the cancer has certain microscopic features that make it more likely to recur


This procedure is a state-of-the-art treatment in which the physician serves as surgeon, pathologist and reconstructive surgeon.Mohs surgeons trace the paths of the tumor using specially prepared frozen sections and a microscope. The steps of the Mohs procedure are summarized below:

Each stage of excision and examination can 30 minutes or longer  depending on the size of the tumor. Large skin cancers will require longer processing time than smaller ones.


The best method of managing the wound resulting from surgery is determined after the cancer is completely removed. When the final defect is known, management is individualized to achieve the best results and to preserve functional capabilities and maximize aesthetics. The Mohs surgeon is also trained in reconstructive procedures and usually will perform the reconstructive procedure necessary to repair the wound. A small wound may be allowed to heal on its own, or the wound may be closed with stitches, a skin graft or a flap. If a tumor is larger than initially anticipated, another surgical specialist with unique skills may complete the reconstruction.

Dr. Humphreys is able to reconstruct most wounds with excellent cosmetic results and restore the appearance of the treated site. The photo gallery shows actual patients with skin cancer treated by Dr. Humphreys using Mohs micrographic surgery and reconstructive techniques.

The Mohs Surgeon

The surgeons that perform Mohs micrographic surgery are specially trained dermatologists who also serve as pathologists and reconstructive surgeons. The American College of Mohs Surgery  (ACMS or Mohs College) is the sole professional organization of physicians who have extensive training and experience in Mohs micrographic surgery. To be accepted as members of the Mohs College, physicians must complete a residency in dermatology plus a one- or two-year fellowship program approved by the Mohs College that includes extensive training in pathology and reconstructive surgery for a total of four to five years of specialized training. Currently more than 50 training centers around the United States are recognized by the College for instruction in Mohs micrographic surgery.

Only physicians that have received special training in this technique can produce the high cure rates associated with Mohs micrographic surgery. While there is currently no required board certification for Mohs surgeons, only physicians that have completed a one year or longer fellowship program after residency are approved by the American College of Mohs Surgery  (ACMS). The Mohs College should not be confused with other organizations with similar names which do not have advanced training requirements and have significantly different criteria for membership. Only the ACMS requires extensive monitored fellowship training and demonstration of competence in the technique of Mohs micrographic surgery and reconstruction. Dr. Humphreys is a full member of ACMS. For additional information please visit the ACMS website (www.mohscollege.org)