Mohs Surgery

Mohs surgery is a technique for the microscopically-controlled excision of skin cancer, producing the highest cure rate for non-melanoma skin cancers suitable for the procedure.  The technique combines surgical removal of the skin cancer in a precise layer-by-layer removal, with immediate microscopic examination of the removed tissue, using horizontal frozen sections to ensure no tumour remains.  Once clearance is achieved the wound can be repaired.  The process should not be confused with frozen sections, which refer to random, intermittent sections examining only a small area of the overall specimen.

Mohs surgery is not required for treating all skin cancers. At Scars & Lasers, we reserve its use for cancers on the face and neck, where other treatment methods are often less effective.

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Skin cancers in these areas are more likely to be inadequately treated with common approaches such as cryosurgery (freezing treatment), curettage and electrodesiccation (scraping and burning), simple excision, Imiquimod (Aldara cream), photodynamic therapy (PDT), or radiation therapy. Additionally, face and neck tumors are often more biologically aggressive and have a higher risk of incomplete excision with standard surgery.

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Many skin cancers have invisible extensions or “roots” beneath the surface, especially if they have been previously treated. On the face, surgeons are often hesitant to remove excess healthy-looking skin to ensure complete cancer removal, as this can lead to both functional and cosmetic concerns. Typically, standard skin cancer surgery requires margins of 4-25mm of surrounding healthy skin to achieve a 95% success rate. While this is usually feasible for skin cancers on other parts of the body, removing even an extra 3mm of tissue on the eyelids, nose, or lips can have significant consequences.

Mohs surgery overcomes this challenge by precisely tracking and removing cancerous roots while preserving as much healthy tissue as possible. This results in higher cure rates and minimal scarring.

Not all facial and neck tumors require Mohs surgery, but it is particularly beneficial for tumors that:

• Have recurred after previous treatment or were incompletely excised.
• Exhibit aggressive histological subtypes, such as  infiltrating, morphoeic or sclerosing types.
• Are large (greater than 2cm in diameter).
• Develop in embryological cleavage planes of the face, including the nasal creases and areas around the ears.
• Occur in areas where tissue preservation is critical, such as the ears, eyelids, lips and nose.
• Are high-risk or aggressive squamous cell carcinomas (e.g., larger than 2.0cm, infiltrative histology, or poorly differentiated).

By selectively using Mohs surgery for these cases, we maximize treatment success while preserving both function and appearance.

• The exact size of the final defect, following clearance, cannot be predicted prior to surgery. The tumour may be much larger than estimated from the surface appearance
• A scar will remain at the site of removal. Every effort is made to obtain optimum cosmetic results, but the primary goal is always to remove the entire tumour
• As a patient, you should understand there is no absolute guarantee that any procedure will be totally free of complications or adverse reactions
• There may be loss of motor (muscle) or sensory (feeling) nerve function in the rare instance where a tumour involves nerve fibres. The nerves must be removed along with the tumour, and if a sensory nerve is injured or removed, numbness results. Sensation will usually, but not always, return
• Rarely, a few patients experience intermittent shooting pain at the surgical area, however this is a very unusual complication
• Because tumours often occur in the head and neck, many are near or on vital structures such as the eyes, nose or lips. In such cases, portions of these structures may have to be removed with resulting cosmetic or functional deformities
• The surgical area may remain tender for several weeks or months after surgery if large amounts of tissue were removed
• Skin grafts and flaps used to cover surgical areas may occasionally not survive
  

Patients should plan to spend the entire morning or afternoon at our centre on the day of Mohs surgery.  The majority of skin cancers are removed on the first stage, however multiple stages are sometimes required.  Each stage of the procedure takes around 30 – 45 minutes, the majority of which time is needed for our on-site laboratory to process the tissue so that it can be examined under the microscope.

You will be asked to return to Scars & Lasers for removal of your sutures following the surgery.  It is also important that you receive regular skin checks with your dermatologist after the procedure to monitor for potential future skin cancers.  The frequency of monitoring will depend on your overall skin cancer risk.