About Mohs Micrographic Surgery
Mohs micrographic surgery, an advanced treatment procedure for skin cancer, offers the highest potential for recovery — even
if the skin cancer has been previously treated. This procedure is state-of-the-treatment in which the physician serves as
surgeon, pathologist and reconstructive surgeon. 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 unharmed. This procedure is most often used in treating
two of the most common forms of skin cancer: basal cell carcinoma and squamous cell carcinoma.
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 chemosurgical technique. 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 chemosurgical technique developed by Dr. Mohs is no longer used. This reduces the normal treatment time 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 the Mohs micrographic surgical
The cure rate for Mohs micrographic surgery is the highest of all treatments for skin cancer. Clinical studies have shown that
Mohs micrographic surgery has a five-year cure rate up to 99 percent in the treatment of basal cell and squamous cell
carcinomas. This procedure, the most exact and precise method of tumor removal, minimizes the chance of regrowth and
lessens the potential for scarring or disfigurement.
Common treatment procedures often prove ineffective because they rely on the human eye to determine the extent of the
cancer. In an effort to preserve healthy tissue, too little tissue may be removed resulting in recurrence of the cancer. If the
surgeon is overcautious, more healthy tissue than necessary may be removed causing excessive scarring. Some tumors do not
respond to common treatments, including those greater than two centimeters in diameter, those in difficult locations and tumors
complicated by previous treatment. Removing a recurring skin cancer is more complicated because scar tissue makes it difficult
to differentiate between cancerous and healthy tissue.
Mohs micrographic surgery is primarily used to treat basal and squamous cell carcinomas, but can be used to treat less
common tumors including melanoma. Mohs surgery is indicated when:
• the cancer was treated previously and recurred
• scar tissue exists in the area of the cancer
• the cancer is in an area where it is important to preserve healthy tissue for maximum functional and cosmetic result,
such as eyelids, nose, ears, lips
• the edges of the cancer cannot be clearly defined
• the cancer grows rapidly or uncontrollably
The Mohs process includes a specific sequence of surgery and pathological investigation. Mohs surgeons examine the
removed tissue for evidence of extended cancer roots. Once the visible tumor is removed, Mohs surgeons trace the paths of
the tumor using two key tools:
• a map of the surgical site
Once the obvious tumor is removed, the Mohs surgeon:
• removes an additional, thin layer of tissue from the tumor site
• creates a “map” or drawing of the removed tissue to be used as a guide to the precise location of any
• microscopically examines the removed tissue thoroughly to check for evidence of remaining cancer cells
If any of the sections contain cancer cells, the Mohs surgeon:
• returns to the specific area of the tumor site as indicated by the map
• removes another thin layer of tissue only from the specific area within each section where
cancer cells were detected
• microscopically examines the newly removed tissue for additional cancer cells
If microscopic analysis still shows evidence of disease, the process continues layer-by-layer until the cancer is completely gone.
This selective removal of only diseased tissue allows preservation of much of the surrounding normal tissue. Because this
systematic microscopic search reveals the roots of the skin cancer, Mohs surgery offers the highest chance for complete
removal of the cancer while sparing the normal tissue.
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 often 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.
Besides its high cure rate, Mohs micrographic surgery also has shown to be cost effective. In a study of costs of various types
of skin cancer removal, the Mohs process was found to be comparable when compared to the cost of other procedures, such
as electrodessication and curettage, cryosurgery, excision or radiation therapy. Mohs micrographic surgery preserves the
maximum amount of normal skin and results in smaller scars. Repairs are more often simple and involve fewer complicated
With its high cure rate, Mohs surgery minimizes the risk of recurrence and eliminates the costs of larger, more serious surgery
for recurrent cancers. Because the Mohs procedure is performed in the surgeon's office and pathological examinations are
immediate, the entire process can often be completed in a single day.
The Mohs Surgeon
The highly trained surgeons that perform Mohs micrographic surgery are specialists both in dermatology and pathology. With
their extensive knowledge of the skin and unique pathological skills, they are able to remove only diseased tissue, preserving
healthy tissue and minimizing the cosmetic impact of the surgery.
The American College of Mohs Micrographic Surgery and Cutaneous Oncology currently recognizes more than 60 training
centers where qualified applicants receive comprehensive training in Mohs micrographic surgery. The minimum training period
is one year during which the dermatologist acquires extensive experience in all aspects of Mohs surgery, pathology and training
in reconstructive surgery.
The above information can be found at www.mohscollege.org