Mohs Micrographic Surgery

Pre-Operative Instructions | Post-Operative Instructions

What is skin cancer?

Cancer is the abnormal growth of cells at an uncontrolled and unpredictable rate. The cancer tissue usually grows at the expense of surrounding normal tissue. In the skin, the most common types of cancer are basal cell carcinoma and squamous cell carcinoma. The names reflect the cell within the skin from which the particular type of skin cancer originates. In the Mohs Surgery Unit we treat basal cell carcinomas, squamous cell carcinomas and some more unusual skin tumors, including some early melanomas. Malignant melanoma or a “cancerous mole” is a rare type of skin cancer that usually appears as a dark colored spot or bump on your skin and slowly enlarges.

What is Mohs surgery?

mohs surgery for skin cancer -slide preparationIn the early 1940’s, Dr. Fredrick Mohs, professor of surgery at the University of Wisconsin, developed a form of treatment for skin cancers he called chemosurgery. “Chemosurgery” is derived from the words “chemical” and “surgery”. The addition of “Mohs” honors the doctor who developed the technique. It is a highly specialized form of treatment for the total removal of skin cancers. It is performed by a team of medical personnel that includes physicians, nurses and technicians.

The physician heading the team has had subspecialty (fellowship) surgical training in the technique and is recognized by the American College of Mohs Micrographic Surgery and Cutaneous Oncology. Other physicians on the team may include fellows and residents who assist while learning the technique. The nurse is an important part of the team who helps answer your questions, responds to your anxieties, assists in surgery and instructs you in dressing and wound care after the surgery is performed. A technician, whom you may not even meet, performs the important task of preparing the tissue slides that are examined under a microscope by the physician.

The word “chemosurgery” when used today is really a misnomer. When Dr. Mohs initially introduced the procedures, he applied a chemical (zinc chloride) to the tumor and surrounding skin which fixed the tissue prior to its removal. Since 1974, the procedure has been refined and improved upon, so the vast majority of cases are done using fresh tissue (omitting the chemical paste).

Although the official name for the procedure is Mohs micrographic surgery, we prefer the shortened version of Mohs surgery. The surgery is performed as follows: the skin that is suspicious for cancer is treated with a local anesthetic so there is no pain in the area. To remove most of the visible skin cancer, the tumor is scraped using a sharp instrument called a curette. A thin piece of tissue is then removed surgically around the scraped skin and carefully divided into pieces that will fit on a microscope slide. The edges are marked with colored dyes; a careful map or diagram of the removed tissue is made; and the tissue is frozen by the technician. Thin slices can then be made from the frozen tissue and examined under the microscope by the doctor. Most bleeding is controlled using pressure and other routine measures, although occasionally a small blood vessel is encountered that must be tied using suture material. A pressure dressing is then applied, and the patient is asked to wait while the slides are being processed. The physician will examine the slides under the microscope and be able to tell if any tumor is still present. If cancer cells remain, they can be located by referring to the map. Another layer of tissue is then removed, and the procedure is repeated until the physician is satisfied that the entire base and sides of the wound have no cancer cells remaining. As well as ensuring total removal of the cancer, this process preserves as much normal, healthy surrounding skin as possible.

mohs surgery for skin cancer -slide preparationThe removal and processing of each layer of tissue takes approximately one hour. Only 20 to 30 minutes of that is spent in the actual surgical procedure. The remaining time is required for slide preparation and interpretation. It usually takes removal of two or three layers of tissue (called stages) to complete the surgery. Therefore, by beginning early in the morning, Mohs surgery is generally finished in one day. Sometimes, however, a tumor may be extensive enough to necessitate continuing surgery a second day.

At the end of Mohs surgery, you will be left with a surgical wound. This wound will be dealt with in one of several ways. The several options will be discussed with you in order to provide the best possible cosmetic results without disguising the small possibility of a recurrence. The possibilities include:

Healing by spontaneous granulation involves letting the wound heal by itself. This offers a good chance to observe the wound as it heals after removal of a difficult tumor. Experience has taught us that there are certain areas of the body where nature will heal a wound as nicely as any further surgical procedures. There are also times when a wound will be left to heal knowing that if the resultant scar is less than optimal, some form of reconstructive surgery can be performed at a later date.

Closing the wound with stitches is often performed on a small lesion. This involves some adjustment of the wound and sewing the skin edges together. This procedure speeds healing and can offer a good cosmetic result. For example, the scar can be hidden in a wrinkle line.

Skin grafts involve covering a surgery site with skin from another area of the body. There are two types of skin grafts. The first is called a split-thickness graft. This is a thin shave of skin, usually taken from the thigh, which is used to cover a surgical wound. This can be either a permanent coverage or temporary coverage before another cosmetic procedure is done at a later date. The second graft-type is the full-thickness graft. This graft requires a thicker layer of skin to achieve proper results. In this instance, skin is usually removed from around the area or collar bone or in front of the ear (the donor site), and stitched to cover a wound. The donor site is then sutured together to provide a good cosmetic result.

Skin flaps involve movement of adjacent, healthy tissue to cover a surgical site. Where practical, they are chosen because of the excellent cosmetic match of nearby skin.

If your Mohs Surgery is extensive, we may recommend you visit one of several consultant physicians. If you have been sent to us by a physician skilled in skin closures (for example, a plastic or reconstructive surgeon), he or she will take care of you after your cancer has been removed.

In summary, by microscopically pinpointing affected areas and removing these tissues, the Mohs surgeon can successfully remove your skin cancer. Because normal tissue is preserved to the greatest extent possible, the Mohs surgeon is able to offer you the possibility of a good cosmetic result. Although an attempt will be made to minimize the scar, you will be left with a scar of some kind.

What happens on the day of surgery?

Your appointment has purposely been scheduled early in the day, and upon your arrival you should check in at the registration window. When the surgical suite becomes available, you will be escorted in by our surgical nurse. If you have not had a consultation visit, she will go through the procedure with you, examine the questionnaire you have answered, and answer any questions you have. The Mohs surgeon will also be available to answer questions.

After preliminary preparation of the skin, you will be placed on the surgical table and the area around your skin cancer will be anesthetized (numbed) using a local anesthetic. This may be uncomfortable, but usually this is the only pain you will feel during the procedure. Once the area is numbed, a layer of tissue will be removed and the bleeding controlled. The removed tissue will be carefully handled by the surgeon, diagrammed, and sent to the technician to be processed into microscopic slides. A pressure dressing will be over your surgical wound, and you will be free to leave the surgical suite. On the average, it takes an hour for the slides to be prepared and studied. During this time you will rest in the waiting room, read your book or magazine, and enjoy some hot tea, coffee or cookies.

Most Mohs surgery cases are completed in two or three stages. Each stage involves the removal and microscopic examination of your skin for cancer. Therefore, the majority of cases are finished in one day. Once we are sure that we have totally removed your skin cancer, we will discuss with you our recommendations for dealing with your surgical wound. Usually, the wound will be closed the same day.

What can I expect after the surgery is complete?


Most people are concerned about pain. You will experience remarkably little discomfort after your surgery. Due to its potential to cause bleeding, we request that you do not take advil or motrin, but instead take Tylenol or a Tylenol-like pain killer. A stronger pain medicine will be prescribed if needed.


A small number of patients will experience some post-operative bleeding. It 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; 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, Dr. Vine can be reached 24 hours a day by calling (609) 529-2408. If necessary, visit a local emergency room for assistance. Your wound care instructions will also list phone numbers if you have questions.


There are some minor complications which may occur after Mohs surgery. A small red area may develop around your wound. This is normal and does not necessarily indicate infection. However, if the redness does not subside in two days or the wound begins to drain pus, you should notify your physician immediately.

Itching and redness

Itching and redness around the wound, especially in areas where adhesive tape has been applied, are not uncommon. If this occurs, ask your pharmacist for a non-allergenic tape and tell us on your return visit.

Swelling and bruising

Swelling and bruising are very common following Mohs surgery, particularly when performed around the eyes or forehead. This usually subsides within four to five days after surgery and may be decreased by the use of an ice pack in the first 24 hours.


At times, the area surrounding your operative site will be numb to the touch. This area of numbness may persist for several months or longer. In some instances it may be permanent. If this occurs, please discuss it with your physician at your follow-up visit.

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 whatever type of wound you have.