The Bottom Line

Mohs surgery is the gold-standard treatment for squamous cell carcinoma (SCC) on the face, ears, scalp, hands, and other high-risk areas. The surgeon removes the cancer one thin layer at a time and checks each layer under a microscope the same day, stopping only when every margin is clear. Cure rates for SCC treated with Mohs exceed 95%. Most people go home the same day, and the wound is repaired immediately after the cancer is gone.

What Is Mohs Surgery?

Mohs surgery — named after Dr. Frederic Mohs, who developed the technique in the 1930s — is a precise method of removing skin cancer that conserves as much healthy tissue as possible while making sure all the cancer is gone before you leave the operating room.

Unlike standard excision, where the surgeon removes the tumor with a margin of normal skin and sends it to a pathology lab that takes days to process, Mohs maps and examines 100% of the surgical margins the same day in an on-site lab. This combination of complete margin control and same-day results is what makes Mohs the treatment of choice for squamous cell carcinoma in cosmetically sensitive or functionally important locations.

Why Is Mohs Used for Squamous Cell Carcinoma?

Squamous cell carcinoma is the second most common skin cancer. Most SCCs are caught early and cured easily, but certain tumors carry a higher risk of coming back or spreading:

  • Location on the face, ears, scalp, lips, or hands
  • Tumors larger than 2 cm
  • Poorly defined borders
  • Recurrent tumors (SCC that came back after a previous treatment)
  • SCC in patients who are immunosuppressed (organ transplant recipients, for example)
  • Deeply invasive or nerve-involving tumors

For these higher-risk situations, Mohs surgery delivers the highest cure rate — above 95% for primary SCC — while removing the least amount of healthy tissue. That matters especially on the nose, eyelids, ears, and lips, where every millimeter of tissue affects appearance and function.

How the Procedure Works, Step by Step

Step 1 — Numbing the area. Your surgeon injects local anesthetic (lidocaine with epinephrine) around the tumor. The epinephrine also helps reduce bleeding. You are awake but feel no pain.

Step 2 — Removing the first layer. The surgeon uses a scalpel to remove the visible tumor along with a very thin margin of surrounding tissue. The wound is bandaged, and you wait in a comfortable area while the tissue is processed.

Step 3 — Lab processing. A technician in the on-site lab freezes the tissue, cuts it into sections, stains it, and mounts it on glass slides. The surgeon examines 100% of the undersurface and edges under a microscope — a process that typically takes 45 to 90 minutes per stage.

Step 4 — Decision point. If cancer cells are found at any margin, the surgeon marks exactly where on a detailed map, then removes only that precise area in a second stage. This process repeats until all margins are clear.

Step 5 — Wound repair. Once margins are confirmed clear, the surgeon repairs the wound. Small defects close with simple sutures. Larger wounds may need a local skin flap (using nearby tissue) or a skin graft. The best repair is chosen based on defect size and location.

Most Mohs procedures for SCC require one or two stages and are completed in a single office visit lasting three to five hours.

Wound Closure: What Are Your Options?

The size and location of the wound after Mohs determine how it is repaired:

  • Primary closure (direct suturing): For small defects, the wound edges are brought together with sutures. This gives the best scar outcome.
  • Local flap: Nearby skin is repositioned to fill the wound. Flaps match skin color and texture well and are commonly used on the nose, cheek, and forehead. Several designs exist — advancement, rotation, bilobed, and rhombic flaps among them.
  • Skin graft: A thin piece of skin taken from another area (often behind the ear or the inner arm) is placed over the wound. Full-thickness grafts give better cosmetic results; split-thickness grafts are used for larger wounds.
  • Healing by secondary intention: The wound is left to close on its own. This works well in certain locations such as the inner corner of the eye or the back of the ear and can produce surprisingly good results over 4 to 8 weeks.

Recovery: What the First Weeks Look Like

Days 1 to 3

Some oozing, swelling, and bruising around the wound is normal. Control mild pain with over-the-counter pain relievers. Keep the wound elevated when possible (especially for facial surgery). Apply antibiotic ointment twice daily and keep the dressing clean and dry.

First Two Weeks

Gently clean the wound once daily with mild soap and cool water, then reapply antibiotic ointment. Avoid heavy lifting, vigorous exercise, and swimming. Sutures on the face come out at 5 to 7 days; on the trunk or limbs, 7 to 14 days; on the legs, around 14 days. Do not pick at scabs.

Weeks 3 to 12 — Scar Maturation

Scars are often red and slightly raised at first. Once sutures are out and the wound is sealed, gentle massage (2 to 3 times daily for 5 minutes) helps soften scar tissue. Silicone gel sheets worn 12 or more hours a day can flatten and fade scars. Apply SPF 30+ sunscreen to the scar every day for at least three months — sun exposure can permanently darken healing skin.

Most scars reach their final appearance at 12 to 18 months. What looks worrying at six weeks often looks dramatically better at one year.

When to See a Dermatologist

  • You notice a new growth or sore on any sun-exposed area of skin
  • A sore does not heal within four to six weeks
  • You have already been treated for SCC — regular follow-up is essential since prior SCC raises your risk of future skin cancers
  • You develop increasing redness, warmth, pus, or fever after Mohs surgery (signs of infection)
  • You notice heavy or persistent bleeding from the wound
  • You have a personal or family history of many skin cancers
  • You are immunosuppressed — SCC behaves more aggressively in organ transplant recipients and others on immunosuppressive therapy

Frequently Asked Questions

Will I be awake during Mohs surgery?

Yes. Mohs is performed under local anesthesia, meaning only the area being treated is numbed. You are awake and comfortable throughout. General anesthesia is rarely needed. Most patients describe minimal discomfort — the anesthetic injection is usually the most uncomfortable part.

How long will the scar be?

Scar size depends on the tumor size, how many Mohs stages were needed, and the repair method chosen. Mohs is designed to remove as little healthy tissue as possible, so scars are generally smaller than with standard excision. Facial scars placed along natural skin creases are often barely visible after one year.

What are the chances of SCC coming back?

Mohs surgery cures more than 95% of primary (first-time) SCCs and about 90% of recurrent SCCs. Your surgeon will recommend a follow-up schedule — typically every 3 to 6 months for the first couple of years — to catch any recurrence early and screen for new skin cancers.

Can I take my blood thinners before surgery?

Talk with your Mohs surgeon and the prescribing physician before stopping any blood thinner. In most cases, aspirin, warfarin, and newer anticoagulants are continued through Mohs surgery because the risk of stroke or clot from stopping them outweighs the added bleeding risk during the procedure. Good surgical technique keeps bleeding well controlled.

References

  1. Connolly SM, et al. AAD/ACMS/ASDSA/ASMS 2012 appropriate use criteria for Mohs micrographic surgery. J Am Acad Dermatol. 2012;67(4):531-550.
  2. Breuninger H, Schaumburg-Lever G. Control of excisional margins by conventional histopathological techniques in the treatment of skin tumours. J Pathol. 1988;154(2):167-171.
  3. Singer AJ, Dagum AB. Current management of acute cutaneous wounds. N Engl J Med. 2008;359(10):1037-1046.
  4. Aarabi S, Longaker MT, Gurtner GC. Hypertrophic scar formation following burns and trauma. PLoS Med. 2007;4(9):e234.
  5. Gold MH. Topical silicone gel sheeting in the treatment of hypertrophic scars and keloids. J Dermatol Surg Oncol. 1994;20(7):431-438.
  6. Pollack SV. Wound healing for the clinician. Adv Dermatol. 1990;5:87-113.

Trusted Resources

Always consult a board-certified dermatologist or Mohs surgeon for personalized medical advice about your skin cancer diagnosis and treatment options.