Mohs Surgery

Mohs micrographic surgery is a specialized surgical procedure used to treat skin cancers, typically of the head and neck. Recurrent or more advanced tumors of the rest of the body are sometimes treated with Mohs surgery as well. The technique offers two main advantages over traditional skin cancer removal treatments:

  • The best cure rate. Mohs surgery for primary basal cell carcinoma, for example, has a 98% cure rate
  • Tissue sparing. Because Mohs surgery is a tissue-sparing surgery, where only the skin with tumor in it is removed, the patient is left with the smallest defect possible. Smaller defects mean smaller scars in the end after the defect is closed. In traditional excisions, the edges are not checked in “real-time” so safety margins are necessary. This often leads to larger defects and eventually larger scars. On the face, even a couple of millimeters difference in a scar length can make a big cosmetic difference.

Mohs surgery involves a same-day procedure where an initial “layer” is taken (the clinical tumor) and examined under the microscope for any involvement of the edges while the patient waits. The tissue is mapped in such a way so that if there is tumor at any one edge, the surgeon knows exactly which edge this is and can go back to take another small piece of skin from this edge only (instead of another whole circle around the defect, leaving a larger defect than necessary).


Dr. Ken K. Lee specializes in all aspects of dermatologic surgery with a special emphasis on Mohs Micrographic Surgery and reconstructive surgery. Dr. Lee is interested in dermatology’s balance of surgery and artistry. His primary focus is Mohs micrographic surgery, which entails the precise and meticulous removal of skin cancers followed by reconstructive surgery. He has received fellowship training specifically for Mohs micrographic surgery and has performed more than 30,000 cases over the last 20+ years.

Frequently Asked Questions

The two most common skin cancers treated with Mohs surgery are basal cell carcinoma and squamous cell carcinoma. The cure rates with Mohs surgery are up to 99% for primary cancers and 95% for recurrent cancers. Other types of skin cancers such as sebaceous carcinoma, atypical fibroxanthoma, dermatofibrosarcoma protuberans, and others can also be treated with Mohs surgery.

Most patients are scheduled directly for Mohs surgery without a preoperative visit. A brief consultation will be done on the day of the procedure. If you would like to see Dr. Lee in consultation prior to your surgery date, we will gladly schedule an appointment upon request.

The surgery is performed under local anesthesia. We suggest that you eat a normal breakfast or lunch unless otherwise specified. Please bathe or shower and wash your hair to minimize your risk of a surgical site infection.

It is recommended you do no travel or plan to participate in athletic activities for 7-10 days following surgery, please plan accordingly.

It is important that you do NOT take any anti-anxiety medicines, muscle relaxants, narcotic pain medicines or similar types of medicines that may cause drowsiness or alter your mental statues on the morning of the surgery. Once you have consulted with Dr. Lee, we can provide you with an anti-anxiety medication. For Mohs surgery, you will be here for several hours, so bring a book, magazine, or laptop. We recommend that you have someone accompany you to give you a ride home. This is a requirement if you receive anti-anxiety medicines.

It is essential that you are able to positively identify the biopsy site on which surgery will be performed. If you cannot, please let us know ahead of time. You may need to go to your referring physician to have the site marked.

Many patients are on blood thinning medications that are prescribed by their physicians. We do not recommend stopping them without explicit permission from the prescribing physician. For those on Coumadin/Warfarin, please make sure that your INR is in the therapeutic range. if approved by your prescribing physician, please discontinue any blood thinning medications one week prior to surgery. Do not discontinue any recommended medications, including aspirin, without permission from your prescribing doctor.

Please stop taking anti-inflammatory medicines (like ibuprofen, Advil, Motrin, Naprosyn, Anacin, and Bufferin), alcohol, vitamin E, gingko biloba, fish oil, and garlic pills at least one week before your surgery. These can increase your risk of bleeding during surgery.

Please bring photo ID and your current insurance card(s) with you to your appointment. If you will be a new patient to Portland Dermatology Clinic, we strongly encourage you to complete our new patient forms through our online Patient Portal prior to your scheduled appointment. Once scheduled, our office will gladly provide you with access. If you would prefer to complete hard copies, let us know and we can mail them prior to your scheduled appointment. You can then bring them competed to your appointment.

View and print a ‘Preparing for Surgery with Dr. Lee’ handout. If you have questions, please call our office at 503-445-2136.


  • Most people will experience remarkably little discomfort after surgery. Usually, Tylenol is sufficient to control the pain. If you would like a stronger prescription pain medication, we will gladly prescribe this for you.

Bruising and swelling

  • Bruising and swelling are common following surgery and usually lasts for several days. Applying ice in the first 24 hours helps reduce these symptoms.


  • The infection rate is very low. A preoperative antibiotic may be recommended to some patients. It is typical to develop some redness along the suture line but if it becomes more extensive or if you develop increasing pain, swelling, drainage, please notify us immediately.


  • The risk of significant post-operative bleeding is very low. Upon completion of the surgery, a pressure bandage will be placed on the wound. A small number of patients may have some post-operative bleeding as the epinephrine (adrenaline) in the anesthetic wears off. This usually can be stopped with direct pressure for 20 minutes. For any bleeding that is not controlled with pressure, we need to be notified immediately.


  • 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 will often be longer than what you may have anticipated because cancer that is underneath the surface is larger than what is visible before surgery. The scar may also need to be lengthened to better fit the contours of the skin. Scars can take a few months or longer to heal completely. 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, which will explicitly outline how to take care of whatever type of wound you have.

Activity and Follow-up

  • You should plan on decreased activity and restrict travel for 1 week, and in some cases longer. This is important in order to minimize the scar from spreading and to reduce the chances of bleeding. In some cases where the wound is on the legs, you may be placed on crutches. You will be asked to follow up in 1 to 2 weeks and may subsequently need more follow-ups.


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