October 9, 2015

Mohs Surgery


What is Mohs surgery?

Mohs surgery is a specialized, highly effective technique for removing skin cancers. It was developed in the 1930’s 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 has 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.

Why remove skin cancers with Mohs surgery?

Some skin cancers are deceptively large—far bigger under the skin than 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 deep under the scar tissue that has formed. Mohs surgery is specially designed to remove these cancers by 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 a 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 slices 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. Dr. Hopp 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 are examined. All microscopic roots of the cancer can thus be precisely identified and pinpointed on the Mohs map.
  3. If more cancer is found on the microscopic slides, Dr. Hopp 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.

Will I have pain, bruising or swelling after surgery?

Most patients do not complain of significant pain. If there is discomfort, 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. Please check with your insurance carrier for exact information relating to your surgery.

How do I prepare for surgery?

Get a good night’s rest and eat normally the day of surgery. If you are taking prescription medications, continue to take them unless otherwise directed. Please continue all current medications as prescribed. 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.

Preparing for your Mohs surgery


  • Shower and shampoo the night before and the morning of surgery.
  • Eat normal meals before surgery
  • Tell the doctor if you have any allergies to medications or have a bleeding problem.
  • Bring a list of medications to give to the doctor. Take all of your regular medications as directed.
  • Wear loose, washable clothing, preferably a button down shirt. Please leave jewelry at home. If the surgery is performed on the face, please refrain from wearing make-up.
  • Wear warm socks to the office.
  • Tell the doctor if you have a cold, get faint around needles or don’t feel well.
  • You may want to have someone drive you home from the office after the surgery. A friend or a relative can keep you company in the exam room or reception area. We can call your ride to pick up one half hour before your ready to leave.

Before surgery:

  • You may take some Tylenol to prevent discomfort before or after the surgery.
  • Be sure to use the restroom before the surgery. The receptionist can show you the nearest location.
  • Please ask if you have any questions before, during or after surgery. We want to ensure a successful surgery.

During surgery:

  • The procedure will take some time, so be sure to bring a book, paperwork or magazine to read. Plan on spending the entire morning at the office.
  • Vending machine and coffee are available at the office, but you are more than welcome to bring snacks and beverages with you for the waiting period.

After surgery:

  • The nurse will go over wound care of the surgical site and provide you with a packet for treatment.
  • Avoid any strenuous physical activities for the remainder of the day. The more peace and quiet, the better.
  • Don’t hesitate to call the office if you have any questions or concerns during your recovery.
  • For routine questions or problems, please call the office during working hours. If you have any emergency problems or questions that can’t wait until we’re open, look for Dr. Hopp’s personal number on your paperwork or call 911 or go directly to the emergency room nearest you.

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