Mohs Surgery

Mohs Surgery

What is Mohs Surgery?

Mohs surgery is a precise surgical technique used to treat skin cancer. During Mohs surgery, layers of cancer-containing skin are progressively removed and examined until only cancer-free tissue remains. Mohs surgery is also known as Mohs micrographic surgery.

The goal of Mohs surgery is to remove as much of the skin cancer as possible, while doing minimal damage to surrounding healthy tissue. Mohs surgery is usually done on an outpatient basis using a local anesthetic.

Mohs surgery is an improvement to standard surgery (local excision), which involves removing the visible cancer and a small margin of healthy tissue all at once. Mohs surgery allows surgeons to verify that all cancer cells have been removed at the time of surgery. This increases the chance of a cure and reduces the need for additional treatments or additional surgery.


Dr. Skelley attended medical school at the University of Kentucky College of Medicine and fulfilled an internship at Indiana University Health Ball Memorial Hospital. His residency was at Mayo Clinic Department of Dermatology where he also had a Mohs Micrographic Surgery and Dermatologic Oncology Fellowship.


Stephen D. Behlmer, M.D. is a physician who is Board Certified in general dermatology with extra specialty training and expertise in cancer surgery, cosmetic surgery and reconstructive surgery. Associated Dermatology and Advanced Laser Clinic provides Helena, and the surrounding Montana communities an extremely experienced and highly trained skin cancer surgeon.

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 the other skin cancer treatments in that it permits the immediate and complete microscopic examination of the removed cancer tissue. Mohs surgery has the highest reported cure rate of all treatments for skin cancer.

Mohs surgery is ideal for skin cancers that grow back after previous treatment, that are at high risk of recurring, or that are located in areas where preservation of the maximum amount of normal skin is important, such as on the face, ears, nose and scalp. Persons at higher risk of skin cancer recurrence include those who have a history of previous skin cancers and those who have had organ transplantation.


Skin cancers may be larger under the microscope than they appear to the naked eye. These cancers may have “roots” in the skin or along blood vessels, nerves, or cartilage. Skin cancers that recur after previous treatments also may send out extensions deep under the scar tissue that has formed. Mohs surgery is specifically designed to remove these cancers by tracking and removing the cancerous “roots” or edges.


There are three steps involved in Mohs surgery:
  1. The skin is made completely numb using a local anesthetic. The visible cancer is then removed with a thin layer of additional tissue. This takes only a few minutes and the specimen is taken to the lab for processing. 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 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. Finally, Dr. Skelley carefully examines the slides under the microscope, which 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. Any microscopic roots of the cancer can thus be precisely identified and pinpointed on the Mohs map.

If more cancer is seen at the edges on the microscopic slides, Dr. Skelley uses the Mohs map as a guide to remove additional tissue only where cancer is present. This allows the Mohs surgery technique to leave the smallest possible surgical defect because no guess work is involved in deciding where to remove additional tissue. Only tissue around the “roots” and extensions of cancer is removed.


A “stage” refers to each time additional tissue is taken and examined under the microscope. 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. Please take this into consideration when scheduling your appointment. We ask that you have no other appointments or commitments during the day of your surgery.


When the cancer is removed, Dr. Skelley will discuss with you your options. These may include 1) allowing the wound to heal naturally, without additional surgery, 2) wound repair by Dr. Skelley, or 3) referral to another surgeon for wound closure. There are several ways a surgical site can be closed.


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


Pain and discomfort may occur. If you experience discomfort, Tylenol is recommended. Ibuprofen, if tolerable is also a great pain reliever for the first few days after surgery. However, if you need additional pain medication, please contact Dr. Skelley’s nurses. You may have some bruising and swelling around the wound, especially if surgery is done on the face close to the eyes.


Most insurance policies cover the costs of Mohs surgery and the surgical reconstruction of the wound. Dr. Skelley accepts Medicare assignment for cancer surgery.


Depending on the location and size of the spot, Dr. Skelley may request you to come in for a pre-operative consultation. You are encouraged to request such a consultation to go over any questions you may have regarding your surgery. There is no charge for a pre-operative consultation.


  • Please arrive 20 min prior to your scheduled surgery time to fill out any necessary paperwork.
  • Be sure to give the nurse or have a list of the most up to date information of medications and supplements you are taking. Many medications and herbal supplements can cause bleeding complications. Generally, we ask that you stop any aspirin (which includes baby aspirin), aspirin containing medicines, and aspirin substitutes (Motrin, Advil, Naprosyn, etc.) 14 days before surgery, unless they are medically necessary. It is requested that you discontinue all herbal supplements, including garlic, garlic, ginseng, CoQ10, glucosamine/chondroitin, omega 3s, fish oil, vitamin E 14 days before surgery.
  • *Important: For patients on Coumadin, Plavix, or other blood thinning medications, please let us know. You should continue to take the medication before and after your surgery. Let us know before your scheduled appointment if you will be continuing aspirin or blood thinners. You may be asked to do preliminary blood work (INR level) 2-4 days before surgery for patients continuing their Coumadin.

  • Get a good night’s rest the night before and eat normally the day of surgery. Shower the morning of your appointment as post-operative instructions will be to leave the site dry and bandaged for 24-48 hours. If you’re having facial surgery, do not wear make-up or jewelry. Please let us know if you have a cold or are not feeling well. 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. It’s a good idea to use the restroom before surgery. You may wish to have someone to accompany you to your surgery appointment in case you need someone to drive you home after surgery is completed. Be prepared to spend several hours at Associated Dermatology the day of your surgery. While not typical it is not infrequent that patients spend a large part of their day at the office due to the nature of Mohs surgery.
  • If your surgical site is in a hair bearing area (bearded area, sideburn, hairline, etc.) please do not shave or trim those hairs 4 days prior to surgery. If the hair needs to be removed, we will do that at the time of your surgery.
  • Minimize or abstain from ALCOHOL (wine, beer, liquor etc.) the day before, the day of, and the day after surgery.
  • Do not smoke or minimize smoking as much as possible before and after surgery. Smoking will slow the healing process. Absolutely DO NOT smoke within two hours prior to surgery.

Please ask any questions you may have before, during, or after surgery. We want to make your Mohs surgery a positive and successful experience. Dr. Skelley’s nurses’ direct number is: 406-324-7437. If we are unavailable when you call, we will return your call as soon as we are able.

To learn more about Mohs surgery, visit:

Call Us For An Appointment:

(406) 442-3534
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