Clinical Dermatology

Mohs Micrographic Surgery

What is Mohs surgery?

Mohs surgery is a specialized, highly effective technique for removing skin cancers. It was developed in the 1930s by Dr. Frederick Mohs at the University of Wisconsin and is now practiced throughout the world. Mohs surgery differs from other skin cancer treatments in that it permits the immediate and complete microscopic examination of the removed cancer tissue so that all roots and extensions of the cancer can be eliminated. Mohs surgery had the highest reported cure rate of all treatments for skin cancer. 

Treating all skin cancers with Mohs surgery is not necessary. Mohs surgery is reserved for skin cancers that grow back after previous treatment, cancers that are at high risk of recurring, or cancers that are located in cosmetic areas where preservation of the maximum amount of normal skin is important. 

Physicians who have the training, surgical and laboratory facilities, and staff to perform this specialized technique practice Mohs surgery. Drs. Berrios and Knisley have received extensive training in Mohs surgery and have used Mohs surgery to treat hundreds of skin cancer patients. They are board-certified dermatologists and are Fellows of the American Academy of Dermatology and the American Society of Mohs Surgery.

Why remove skin cancers with Mohs surgery?

Some skin cancers are deceptively large – far bigger under the skin that they appear to be from the surface. These cancers may have “roots” in the skin or along blood vessels, nerves, or cartilage. Also, skin cancers that recur after previous treatments may send out extensions deeps under the scar tissue that has formed. Mohs surgery is specifically designed to remove these cancers be tracking and removing these cancerous “roots.”

How is Mohs surgery done?

There are three steps involved in Mohs surgery:

  1. The skin is made completely numb using local anesthetic. The visible cancer is removed with a thin layer of additional tissue. This takes only a few minutes and the patient may then return to the waiting room. A detailed diagram (a Mohs map) of the removed specimen is drawn.
  2. The specimen is color coded to distinguish top from bottom and left from right. A technician freezes the tissue and removes very thin slices from the entire edge and undersurface. These sliced are placed on microscope slides and stained for examination under the microscope. This is the most time consuming part of the procedure, often requiring an hour or more to complete.
  3. The doctor then carefully examines these slides under the microscope. This allows examination of the entire surgical margin of the removed tissue. That is, the entire undersurface and the complete edge of the specimen is examined. All microscopic roots of the cancer can thus be precisely identified and pinpointed on the Mohs map.

If more cancer is found on the microscopic slides, the doctor uses the Mohs map to remove additional tissue only where cancer is present. This allows the Mohs surgery technique to leave the smallest possible surgical defect because no guesswork is involved in deciding where to remove additional tissue. Only tissue around the “roots” and extensions of cancer is removed.

How long does it take?

Most cases can be completed in three or fewer stages, requiring less than four hours. However, no one can predict how extensive a cancer will be because the size of a skin cancer’s “roots” cannot be estimated in advance. We therefore ask that you reserve the entire day for surgery, in case additional surgical sessions are required.

Will it leave a scar?

Yes. Any form of surgery leaves a scar. Mohs surgery, however, will leave one of the smallest possible surgical defects, and therefore a smaller final scar.

What happens after the Mohs surgery is completed?

When the cancer is removed, the doctor will discuss with you your options. These may include: 1) allowing the wound to heal naturally, without additional surgery (often produces the best cosmetic result), 2) wound repair by the doctor, 3) wound repair by the referring physician or making arrangements for wound repair, or 4) referral to another surgeon for wound closure.

Will I have pain, bruising, or swelling after surgery?

Most patients do not complain of significant pain. If there is discomfort, acetaminophen (Tylenol) is usually all that is necessary for relief. However, stronger pain medications will be prescribed when needed. You may have some bruising and swelling around the wound, especially if surgery is being done close to the eyes.

Will my insurance cover the cost?

Most insurance policies cover the costs of Mohs surgery and the surgical reconstruction of the wound; however, it may be subject to your deductible and coinsurance. Please check with your insurance carrier for the exact information relating to your surgery. Each practice location accepts Medicare assignments for cancer surgery.

How do I prepare for surgery?

Get a good night’s rest and eat normally on the day of surgery. If you are taking prescription medications, continue to take them, unless otherwise directed. However, avoid taking medications that contain aspirin for ten days before your surgery. Also, please do not take any aspirin substitutes, such as Advil, Motrin, Nalfon, Naprosyn, etc. within 24 hours of surgery. You may, however, take acetaminophen (Tylenol) at any time before surgery. You may want to bring a book or magazine with you to occupy your time while waiting for your slides to be processed and examined. Also, the doctors recommend that you arrange for someone to drive you home after surgery is completed.

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