Mohs Surgery, named for Dr. Frederic Mohs, is a precise technique for removing skin cancer, offering the highest cure rates for common types like basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). It is designed to spare the maximum amount of healthy tissue while ensuring the entire tumor is removed. This is particularly important for cancers located on the head, neck, hands, or feet, where preserving function and appearance is a priority. Understanding the flow of the day is helpful for patients preparing for this outpatient procedure.
Preparing for the Procedure Day
Patients should plan to be in the clinic for several hours, typically between three to six hours, depending on the tumor’s complexity. Packing a small bag with reading material, quiet activities, and a snack or drink is advisable. Patients should wear comfortable, loose-fitting clothing that allows easy access to the surgical site. Dressing in layers is recommended since the surgical rooms are often kept cool.
Patients should continue taking regular prescription drugs, including blood thinners like Coumadin or Plavix, but must confirm this with the Mohs surgeon and prescribing physician beforehand. Non-prescription medications and supplements that can increase bleeding, such as aspirin, ibuprofen, or fish oil, are usually stopped one week prior to the surgery. Patients should eat a normal breakfast on the morning of the procedure, as fasting is not required for the local anesthesia.
The Step-by-Step Surgical Process
The procedure begins with the surgeon administering a local anesthetic to numb the area around the skin cancer, allowing the patient to remain awake and comfortable. Once anesthetized, the surgeon removes a thin layer of tissue, known as a stage, which includes the visible tumor and a small margin of surrounding skin. This removed tissue is then meticulously mapped and color-coded with dyes to correspond precisely with the surgical site.
The patient waits while the surgical team takes the tissue to an on-site laboratory for immediate processing using the frozen section technique. The tissue is rapidly frozen, thinly sliced horizontally, and examined under a microscope by the Mohs surgeon, who acts as the pathologist. This horizontal sectioning allows for the microscopic examination of 100% of the peripheral and deep margins of the excised tissue. If no cancer cells are detected at the margins, the site is deemed clear.
If the microscopic examination reveals cancer cells, the surgeon uses the corresponding map to pinpoint the location where the cancerous roots remain. A second, smaller layer of tissue is then removed only from that specific, involved area, sparing healthy tissue. This process of removal, mapping, microscopic analysis, and waiting is repeated in stages until the surgeon confirms that all margins are free of cancer cells.
Immediate Reconstruction and Wound Closure
Once the margins are clear, the focus shifts to repairing the wound, which can range from a small defect to a larger, complex one, depending on the tumor’s size and depth. The Mohs surgeon, who is also trained in reconstructive surgery, closes the wound immediately to improve the functional and cosmetic outcome. For smaller defects, a primary closure may be performed, where the edges are stitched together in a straight line, sometimes forming an elliptical shape to ensure the scar lies flat.
If the wound is larger or in an area with limited loose skin, the surgeon may utilize adjacent tissue to close the defect using a local tissue flap. This technique involves repositioning a segment of healthy skin from the surrounding area over the wound, maintaining its blood supply for better healing. Another option is a skin graft, which involves transplanting a piece of skin from a distant site on the body to cover the defect.
In specific cases, particularly on the ear or lower leg, the surgeon may choose to let the wound heal naturally through a process called secondary intention. This method allows the wound to gradually fill in with granulation tissue and close on its own over several weeks. For very large or anatomically complex defects, the Mohs surgeon may collaborate with a plastic surgeon to perform the reconstruction.
Post-Procedure Care and Long-Term Recovery
Following the closure, a pressure dressing is applied to the surgical site to minimize swelling and reduce the risk of bleeding. Patients receive instructions for at-home wound care, which usually involves keeping the bandage clean and dry for the first 24 to 48 hours. Pain is mild and can be managed effectively with over-the-counter pain relievers, such as acetaminophen.
Activity restrictions are necessary, including avoiding strenuous exercise, heavy lifting, and any activity that could cause tension on the stitches for approximately one to two weeks. Bruising and swelling around the surgical site is expected and may peak within the first couple of days. Patients must monitor the site for signs of infection, such as increasing redness, warmth, persistent pain, or a fever, and contact the clinic immediately if these occur.
Scar management is important, as scars will continue to mature and fade for up to a year or more after the procedure. The surgeon may recommend gentle scar massage or the use of silicone sheeting several weeks post-surgery. Protecting the healing area from sun exposure is also necessary for at least six to twelve months, as ultraviolet radiation can cause the scar to become hyperpigmented or more noticeable.