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Mohs Micrographic Surgery

Dr. Petelin and Dr. Young are two of Arizona’s few skin cancer surgeons who have completed an accredited fellowship in Mohs micrographic and reconstructive surgery.  We hope it won’t ever happen to you, but should a dermatologist identify a skin cancer needing removal, one of our expert Mohs surgeons will handle the procedure and you’ll be in the very best of hands.

About Mohs Surgery

Mohs surgery, also known as chemosurgery, created by a general surgeon, Dr. Frederic E. Mohs, at the University of Wisconsin. It is a microscopically controlled surgery used to treat common types of skin cancer. Mohs surgery is performed under local anesthetic on an outpatient basis. During the surgery, after each removal of tissue, the surgeon examines the tissue specimen in real time for cancer cells, and that examination informs the surgeon where to remove tissue next. Mohs surgery is one of the many methods of obtaining complete margin control during removal of a skin cancer. Mohs surgery allows for the removal of a skin cancer with very narrow surgical margin and a high cure rate. Mohs surgery requires very specfic skills, therfore, it is generally reserved for treatment of skin cancers on the head and neck region or those which meet certain criteria, such as recurrent or exceptionally large tumors.

Mohs Microsurgery FAQ

What does the procedure consist of?

The Mohs surgical process involves a series of surgical excisions followed by microscopic examination of the tissue while you are there to assess if any tumor cells remain. Some tumors that appear small on clinical exam may have extensive invasion underneath normal appearing skin, resulting in a larger surgical defect than would be expected. It is not possible to predict in advance the final size of the surgical defect. As Mohs surgery is used to treat complex skin cancers, approximately half of all treated tumors require two or more stages for complete removal of the cancer. Many require only one stage!

Step 1: Examination of Tumor

Mohs surgery begins with a series of surgical excisions. The tissue is studied to determine if there are tumor cells and how extensive it is underneath the skin. Since Mohs surgery is used to treat more complex skin cancers, about half of all treated tumors require two or more stages to completely remove the cancer.

Step 2: Removal of Visible Tumor

Once the skin has been completely numbed, the tumor is gently scraped with a special surgical instrument. This helps define the clinical margin between tumor cells and healthy tissue. Dr. Petelin then surgically removes the first saucer shaped “layer” of tissue. This process takes approximately 10 minutes.

Step 3: Mapping the Tumor

Once a “layer” of tissue has been removed, a map or drawing of the tissue and its orientation to local landmarks (e.g. nose, cheek, etc.) is made to serve as a guide to the precise location of the tumor. The tissue is labeled and color-coded to correlate with its position on the map. The tissue sections are processed and then examined by the surgeon to thoroughly evaluate for evidence of remaining cancer cells. Compared to other techniques, close to 100% of the margins of skin can be evaluated with the Mohs technique. However, it can take up to 60 minutes to process, stain, and examine one tissue section. During this time you will be comfortably seated in a separate waiting room with coffee and snacks available. You may bring a book or magazine to read.

Step 4: Additional Stages

If any section of the tissue demonstrates cancer cells at the margin, the Dr. Petelin returns to that specific area of the tumor, as indicated by the map, and removes another layer of tissue only where cancer cells were detected. The newly excised tissue is once again mapped, color-coded, processed and examined for additional cancer cells. If microscopic analysis still shows evidence of disease, the process continues layer by layer, until the cancer is completely removed. By beginning early in the morning, Mohs surgery is generally finished in one day, usually the same morning. Rarely, a tumor may be extensive enough to necessitate continuing surgery or perform the reconstruction on the second day.

The true benefit of Mohs surgery is that this technique allows for preservation of as much of the surrounding normal tissue as possible. As an added benefit, because the systematic microscopic search reveals the roots of the skin cancer, Mohs surgery also offers the highest chance for complete removal of the cancer. Cure rates typically range in the 95-98% range when skin cancers are treated with Mohs surgery.

Step 5: Reconstruction

The second and last major component of Mohs surgery is the reconstruction of the surgical defect once all the tumor has been removed. Mohs surgeons are trained in the reconstruction of all types of skin defects. Reconstruction is individualized to preserve normal function and maximize cosmetic outcome. The best method of repairing the wound following surgery is determined only after the cancer is completely removed, as the final defect cannot be predicted prior to surgery. Stitches are often needed to close the wound side-to-side, or a skin graft or a flap may be designed. Sometimes, a wound may be allowed to heal naturally depending on the size and location. Rarely, if the resultant scar is unacceptable, some form of cosmetic surgery can be performed at a later date. Sometimes Dr. Petelin works directly with other specialists to obtain optimal cosmetic results for certain sites, such as the eyelids.

How should I prepare?

No specific preparation is necessary. Eat a light breakfast on the day of the surgery. Please shower and shampoo your hair within 24 hours before your procedure as this will minimize the bacterial growth on your skin and help prevent infection. If you are currently taking medications, continue as usual unless otherwise directed by your physician. Eliminate aspirin or any medications containing aspirin, such as Bufferin or Anacin (unless otherwise directed by your physician), for at least two weeks before surgery because they tend to prolong bleeding during the operation. Also, eliminate medications containing ibuprofen, commonly found in Advil, Nuprin, and Motrin, for at least three days before surgery. If you need a pain reliever, you may take acetaminophen, which is found in Tylenol. Do not drink alcohol one week prior to your procedure.

Because you will be injected with a local anesthetic only, those are no dietary restrictions for the procedure performed in our office. Most patients can drive themselves home after the surgery. If the skin cancer is near the eye, please arrange for someone to drive you.

If you are self-medicating (not told to take by a doctor) with over-the-counter products such as Vitamin E, herbal supplements, Ibuprofen, Aleve, we ask that you discontinue these at least two weeks prior to surgery. If you are on any type of blood thinning medications, including Aspirin, Plavix, or Coumadin, please notify the nurse. Blood thinners increase bleeding during the surgical procedure, and increase the risk of bleeding and other complications after the procedure. However, we do not advise discontinuing any of your prescribed blood thinning medicines.

We also ask that you remain in town for at least one week following your surgical procedure. You will likely be required to return to our office for surgical post-operative visit and suture removal.

What can I expect after the surgery is complete?

Most people are concerned about pain. You will experience relatively little discomfort after your surgery. Taking Tylenol relieves the majority of patients who experience pain. Due to its potential to cause bleeding, we request that you do not take aspirin, or ibuprofen for pain control. In some cases, you may be prescribed a stronger pain medication.

A small number of patients will experience some bleeding post-operatively. This bleeding can usually be controlled by the use of pressure. You should take a gauze pad and apply constant pressure over the bleeding point for 15 minutes at home if this happens. DO NOT lift up or relieve the pressure at all during that period of time. If bleeding persists after continued pressure for 15 minutes, repeat the pressure for another 15 minutes. If this fails, call the office number or after hours number. It is advisable not to drink alcohol the first post-operative night as this may stimulate bleeding. The number to call is (480) 905-8485.

Itching and redness around the wound, especially in areas where adhesive tape has been applied, are not uncommon. Swelling and bruising are very common following Mohs surgery, particularly when it is performed around the eyes or lips. This usually subsides within four to five days after surgery and may be decreased by the use of an ice pack in the first 48 hours. At times the area surrounding your operative site will be numb to the touch. This area of anesthesia (numbness) may persist for several months or longer. In some instances, it may be permanent. Please notify us if you have an increase in your temperature, chills, increasing redness, swelling or drainage, or escalating pain.

Although every effort will be made to offer the best possible cosmetic result, you will be left with a scar. The scar can be minimized by the proper care of your wound. We will discuss wound care in detail with you and give you Wound Care Information Sheets that will explicitly outline how to take care of the specific type of wound you have.

If you have any additional questions don’t hesitate to call us at (480) 905-8485.

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