Mohs Surgery — Precision Treatment for Skin Cancer

Skin cancers are common in New Zealand — but not all are treated the same way. While many cancers can be removed with a simple excision, some require a more precise approach to balance cure rates with cosmetic outcomes. That’s where Mohs micrographic surgery comes in.

At DermLab Hamilton, Mohs surgery is performed by Dermatologists with advanced surgical training. This highly specialised technique allows us to remove cancer layer by layer, examining tissue under the microscope in real time, until we are certain every last cancer cell has been taken — while preserving as much healthy skin as possible.

This article explains what Mohs surgery is, which cancers it’s used for, what to expect on the day, and why it’s considered the gold standard for treating certain skin cancers.

What Is Mohs Surgery?

Mohs micrographic surgery is a stepwise surgical technique used to treat high-risk or complex skin cancers. Unlike standard excision, where the cancer is removed along with a predetermined “margin” of surrounding tissue, Mohs is:

• Layer by layer: Cancer is removed in thin slices.

• Microscope checked: Each layer is examined immediately to see if cancer cells remain.

• Repeated as needed: The process continues until the margins are clear.

This ensures that the cancer is completely removed while sparing the maximum amount of healthy tissue. Cure rates for Mohs are over 99%, the highest of any skin cancer treatment.

📖 Link: Skin Cancer & Moles

Which Cancers Need Mohs Surgery?

Mohs is not necessary for every skin cancer. Many can be managed with simple excision. We reserve Mohs for cancers that are high-risk, recurrent, aggressive, or in delicate locations where tissue preservation matters most.

Basal Cell Carcinoma (BCC)

• Located on the face, eyelids, nose, lips, or ears

• Aggressive or recurrent subtypes

• Ill-defined borders under the skin, making them hard to measure

Squamous Cell Carcinoma (SCC)

• On high-risk sites such as the face, ears, lips, or nose

• Poorly differentiated or aggressive histology

• Cancers that have come back after previous surgery

Rare Cancers

• Dermatofibrosarcoma protuberans (DFSP)

• Sebaceous carcinoma and other less common tumours

📖 Links: Skin Cancer Checks | Skin Cancer & Moles

Why Choose Mohs Over Standard Excision?

1. Higher Cure Rates
   Mohs has cure rates of over, 99% for BCC and SCC, especially important for recurrent or aggressive cancers.

2. Tissue Preservation
   By removing only the tissue that contains cancer, Mohs spares healthy skin. This is vital on the face, where every millimetre matters for appearance and function.

3. Immediate Results
   Patients know before they leave that the cancer is gone — no waiting for pathology results.

4. Better Cosmetic and Functional Outcomes
   Smaller wounds mean smaller scars and easier reconstruction.

📖 Link: Mohs Surgery

The DermLab Approach to Mohs Surgery

At DermLab, Mohs surgery is performed by Dermatologists trained in both surgery and pathology. Patients benefit from:

• Day-stay procedure under local anaesthetic — no need for hospital admission.

• On-site tissue processing — so results are immediate.

• Reconstruction expertise — wounds are repaired straight away, using fine sutures, flaps, or grafts to achieve the best cosmetic outcome.

• Multidisciplinary support — GP Skin Cancer Doctors assist in identifying Mohs cases, performing biopsies, and supporting follow-up care.

📖 Link: Skin Cancer Checks

What to Expect on the Day

1. Check-in & Preparation
   You’ll arrive in the morning. The area is cleaned and numbed with local anaesthetic.

2. First Layer Removal
   A thin layer of tissue is removed from the cancer site.

3. Microscopic Examination
   That tissue is immediately prepared and examined under the microscope to check for cancer cells.

4. Repeat as Needed
   If cancer remains, another thin layer is removed exactly where the cells are still present. This is repeated until no cancer cells are found.

5. Wound Repair
   Once the cancer is fully removed, the wound is repaired. Options include simple stitches, local skin flaps, or grafts, depending on the size and location.

6. Aftercare
   Most patients go home the same day. We provide clear instructions for wound care and schedule follow-up checks.

After Mohs: Ongoing Care

Mohs may be the most precise way to remove a cancer, but treatment doesn’t end there. At DermLab, we support patients with:

• Regular follow-up skin checks to detect new cancers early.

• Sun protection education to prevent recurrence.

• Scar optimisation, sometimes using CO₂ laser resurfacing to improve healing and reduce visible scarring.

📖 Links: Skin Cancer Checks | Laser Dermatology