Your Mohs Surgery Questions Answered

By: Joel Sears, M.D.
Fellowship-Trained Mohs Surgeon, Board-Certified Dermatologist

Going to the dermatologist for that persistent little spot on your face that bleeds occasionally and just won’t heal is an important step in taking care of your skin. The doctor biopsies the lesion, and sure enough, you have skin cancer. You then receive a call from the doctor’s office to schedule Mohs Surgery. So, what in the world is Mohs surgery? As a Fellowship-Trained Mohs Surgeon, I’d like to address many of the common questions I hear from patients, hopefully, to provide a better understanding of this vital procedure.

What is Mohs Surgery used for?

Mohs surgery is a highly specialized procedure used to treat different types of skin cancers, including basal cell carcinoma, squamous cell carcinoma, and some melanomas. Skin cancer is becoming more and more prevalent among all Americans. In fact, it is the most common of all human cancers.

Where did the word MOHS come from?

The name ‘Mohs’ (rhymes with ‘nose’) refers to the doctor who first developed the technique over fifty years ago, Dr. Frederic Mohs. Over the years, the procedure has been updated and refined to become the gold standard for treating skin cancer. The main goal of Mohs surgery is to carefully remove 100% of the skin cancer while sparing as much of the surrounding healthy skin as possible. This is especially important since most skin cancers occur on critical structures of the face, such as the nose, lips, or ears. Mohs Surgery has the highest cure rate of any skin cancer treatment and helps to minimize scarring after the surgery.

What should I expect when I come in for Mohs Surgery?

Mohs surgery takes place in procedure rooms in the Dermatologist’s office. After checking in at the front desk, a surgical assistant will show you to the procedure room and review your medical history. You usually won’t have to change clothes, but you will wear a hospital gown over your clothes. The Provider, a Mohs Surgeon, will examine you, explain the procedure, and answer any questions you may have. After reclining comfortably on the surgical chair, the surgical assistant will wash and prep the surgery site. Patients are awake throughout the procedure, but the surgery site is numbed with a local anesthetic.

What is the Mohs procedure?

After completely numbing the skin, the Mohs surgeon uses a scalpel blade to excise a thin layer of skin tissue delicately and conservatively around the visible skin cancer. The thin skin specimen is handled carefully and taken immediately to the on-site laboratory, where it is tested. This laboratory process may take longer than an hour, so the patient is taken to a separate waiting room where Mohs patients await their results. The skin specimen is processed by specially trained technicians who prepare the tissue layers on microscope slides to be examined by the Mohs surgeon. The Mohs surgeon is trained to be both the surgeon and the pathologist (the doctor who examines the microscopic tissue under a microscope). The entire edge of the specimen, both the periphery surface and the deep underneath surface, is examined under a microscope by the Mohs surgeon. We hope to see normal healthy skin around the entire margin on that first layer, which means the cancer is cleared! However, in about half the cases, cancer is observed at the specimen’s edge, which means there is residual cancer still in the patient. A mapping of the surgery site is drawn by the Mohs surgeon while reading the microscope slides, which informs the surgeon of the precise location of any residual cancer on the patient’s skin. The patient is returned to the operating room, re-anesthetized, and another layer of tissue is removed around that precise site of residual cancer. Areas that did not show any residual cancer are left alone. The laboratory process is then repeated, and the tissue is again examined under the microscope for any extension of skin cancer. Cancer can extend randomly like roots. Only the cancer “roots” are tracked and removed, leaving any surrounding healthy skin intact. Once the layers removed are clear of any residual cancer cells, the skin cancer is gone, and Mohs is finished! (A helpful diagram can be found at this website.)

What happens after the cancer is removed with Mohs?

So, you get the good news: your cancer is gone! What now? Once the cancer is confidently cleared with Mohs surgery, the Mohs surgeon switches their attention from removing the cancer to repairing (or reconstructing) the open surgical wound left after the cancer excision. Most skin cancer occurs on or around the face, so Fellowship-Trained Mohs Surgeons are experts in facial plastic and reconstructive surgery. You are brought back to the operating room a final time to close and repair the open wound. This repair may require only a fine line of stitches or a complicated procedure like a skin graft or skin flap. Mohs surgery performed by a Fellowship-Trained Surgeon ensures not only the complete removal of cancer, but also optimal cosmetic and functional results with facial plastic surgery repair.

Who should I trust to perform my skin cancer surgery?

Not all skin cancer requires Mohs surgery for treatment, but if Mohs is recommended, make sure the doctor is Fellowship trained at a recognized university or certified program.

Fellowship training is additional specialized surgical training above and beyond a dermatology residency training. This fellowship training includes more specialized training in surgical skills, cutaneous oncology, dermatopathology, and facial plastic surgery, which is needed in skin cancer surgery.  Not every doctor who attempts Mohs surgery has the specialized training that assures the best possible outcomes of curing cancer and minimizing scars. Two identifiers that a Mohs surgeon is Fellowship-Trained are:

1) They are a Fellow member of the American College of Mohs Surgery (ACMS), or

2) They are Board Certified by the Micrographic Dermatologic Surgery (MDS) board.

If you are faced with skin cancer requiring Mohs surgery, asking if the surgeon is fellowship-trained assures they have been trained to those standards.

About the Author

Joel Sears, M.D. – Fellowship-Trained Mohs Surgeon, Board Certified Dermatologist
Dr. Sears founded Advanced Dermatology & Skin Cancer Surgery in 1991, devoting his practice to skin cancer and facial plastic surgery. Additionally, Dr. Sears is currently affiliated with the University of Washington School of Medicine WWAMI medical residency program as a Clinical Assistant Professor. Dr. Sears cherishes time with his family when he is not working. He is a private pilot and enjoys skiing, antique clocks, and “puttering around” on his hobby farm.