Mohs surgery is a precise, layered technique used to treat common skin cancers like basal cell and squamous cell carcinomas. This specialized outpatient procedure offers a high cure rate by allowing for the complete removal of cancer cells while preserving the greatest amount of surrounding skin. The high success rate is directly related to the unique process of immediate, on-site microscopic examination of the surgical margins. This approach is particularly valuable for cancers located in functionally or cosmetically sensitive areas, such as the face, hands, or feet.
Preparing for the Procedure Day
Patients should reserve the entire day for the procedure, as the total time required varies significantly depending on the extent of the cancer and the number of stages needed. Appointments typically last several hours. It is helpful to bring reading material or other activities to occupy the time spent waiting between surgical stages.
Patients should continue most regular medications, including prescription blood thinners, unless instructed otherwise by the surgeon. Non-prescription blood thinners like aspirin, ibuprofen, and supplements such as Vitamin E or fish oil are often recommended to be stopped one to two weeks prior to surgery to minimize bleeding risk. A light meal is permitted before the surgery, but patients should avoid alcoholic beverages for a few days prior.
Wearing loose-fitting, comfortable clothing is recommended, particularly a button-down shirt if the surgery is on the head, neck, or trunk. Patients should not wear makeup if the procedure is on the face. Arranging for transportation home is important, especially if the surgical site is near the eye or if any sedative medication is administered.
The Surgical Process: Stages and Waiting
The procedure begins with the administration of a local anesthetic, typically lidocaine, which numbs the surgical area while the patient remains awake. The surgeon first removes the visible portion of the tumor (debulking), followed by the removal of a thin, saucer-shaped layer of surrounding tissue, known as the first stage. This excised tissue is then meticulously mapped and color-coded to correspond precisely to the location on the patient’s skin.
This tissue is immediately transported to an on-site laboratory, where it is flash-frozen and sliced into thin sections using a cryostat. The prepared slides are stained to highlight cell structures, allowing the Mohs surgeon to examine 100% of the peripheral and deep margins under a microscope. This processing and examination typically take an hour or more, creating the patient’s waiting period.
If the microscopic examination reveals residual cancer cells, the surgeon identifies the corresponding location on the map. The patient returns to the surgical suite, and a second stage of tissue is removed only from the area where cancer was detected, sparing healthy tissue. This iterative process continues until the tissue sample is completely clear of cancer.
Immediate Post-Excision: Wound Repair
Once the Mohs surgeon confirms the margins are clear of cancer, the resulting surgical defect is ready for immediate reconstruction. The decision for wound repair is based on the size, depth, location, and surrounding skin tension. The simplest repair is a linear closure, or primary closure, where the skin edges are stitched together, often resulting in a fine, straight-line scar.
For larger defects or those in areas with limited loose skin, the surgeon may perform a local skin flap. This involves repositioning nearby skin and underlying tissue to cover the wound. A flap maintains its own blood supply, which promotes robust healing.
Alternatively, a skin graft may be necessary, involving the transplantation of skin from a distant site on the body, such as behind the ear or the collarbone, to cover the open area. Grafts can be split-thickness, containing only the top layers of skin, or full-thickness, incorporating all layers of skin.
In some cases, the wound may be allowed to heal on its own, a process called healing by secondary intention. This is sometimes preferred for small defects or those in concave areas like the inner corner of the eye. The surgeon will discuss the most appropriate repair option before proceeding with the closure.
Recovery and Long-Term Scar Management
Post-operative recovery begins with managing expected symptoms like mild pain, typically controlled with over-the-counter acetaminophen. Swelling and bruising are common, often peaking within the first 48 hours. These symptoms can be minimized by keeping the surgical site elevated and applying cold packs. Patients are instructed to keep the initial pressure dressing completely dry for the first 24 to 48 hours.
Detailed wound care begins after the initial dressing is removed, usually involving gentle cleansing with mild soap and water. An ointment like petroleum jelly should be applied generously to keep the wound moist. Maintaining a moist healing environment reduces scab formation and optimizes the cosmetic outcome. The wound is then covered with a fresh, non-adherent sterile dressing, and this process is repeated daily until the sutures are removed.
To prevent tension on the healing site, patients should avoid strenuous activity and heavy lifting for at least one week. Sutures are typically removed five to fourteen days after the procedure, depending on the location. The resulting scar will gradually mature over the following months, softening and fading over a period of up to a year. Long-term scar management includes protecting the area from the sun with a high-SPF sunscreen, as UV radiation can cause hyperpigmentation.