If you have been diagnosed with skin cancer, you may have been told that it needs to be surgically removed. But not all skin cancer surgery is the same. Two commonly used approaches are standard surgical excision and Mohs micrographic surgery.
Both can be effective treatments for skin cancer, but they are used in different circumstances. The type of skin cancer, its size, location, previous treatment and risk of recurrence can all influence which approach is recommended.
For skin cancers on the face in particular, preserving as much healthy tissue as possible can also be an important consideration. This is one of the situations where Mohs surgery may be recommended.
At Skin Centre in Tauranga, our specialist dermatologists provide both conventional skin cancer surgery and Mohs micrographic surgery, allowing treatment to be selected according to the individual cancer and patient.
What Is Mohs Surgery?
Mohs surgery is a specialised technique that removes a skin cancer progressively, one layer at a time.
After a layer of tissue is removed, it is prepared and examined under a microscope to determine whether cancer cells remain at the margins. If cancer is identified, the surgeon can map its precise location and remove additional tissue specifically from that area.
This process is repeated until examination shows that the margins are clear of cancer.
An important feature of Mohs surgery is that the tissue is examined during the procedure rather than being sent away for routine pathology afterwards. This allows the surgeon to trace extensions of the cancer that may not be visible from the surface while preserving uninvolved surrounding skin.
What Is Standard Surgical Excision?
Standard surgical excision is another well-established treatment for skin cancer.
During an excision, the visible skin cancer is removed along with a predetermined margin of normal-looking surrounding skin. The specimen is then sent for laboratory examination to determine whether the margins are clear of cancer.
If the pathology results show that cancer cells extend to the margin of the tissue removed, further treatment may sometimes be required.
Standard excision is commonly used for many basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), particularly when the cancer is considered lower risk and is in a location where an appropriate surgical margin can be removed. Surgery remains a cornerstone of treatment for both BCC and SCC.
What’s the Difference Between Mohs Surgery and Standard Excision?
The major difference is how the margins around the skin cancer are assessed.
With standard excision, the surgeon removes the cancer together with a planned margin of surrounding tissue. The specimen is then examined by pathology.
With Mohs surgery, tissue is removed in stages and examined microscopically while the patient waits. If cancer remains in a particular area, the surgeon can return specifically to that location and remove another layer.
This provides Mohs surgery with two important characteristics: a very high degree of margin control and the ability to conserve healthy tissue.
That tissue-sparing ability can be particularly valuable when treating skin cancer on areas such as the nose, eyelids, ears and lips, where removing even a relatively small amount of additional healthy tissue can affect reconstruction, appearance or function.
Why Is Mohs Surgery Often Used for Facial Skin Cancer?
Skin cancers on the face can present some particular challenges.
Firstly, some cancers have microscopic extensions beyond what can be seen with the naked eye. This can make determining the true boundary of the cancer more difficult.
Secondly, there is often relatively little spare tissue around areas such as the nose, eyelids, lips and ears. Preserving healthy skin can therefore be especially important when planning reconstruction following removal of the cancer.
Mohs surgery allows the surgeon to examine the margins microscopically during treatment and continue removing tissue only where cancer cells remain.
The American Academy of Dermatology notes that Mohs is commonly recommended for certain BCCs and SCCs that are aggressive, large, recurrent or situated in locations where there is little tissue beneath them, including the eyelids, nose, ears and scalp.
At Skin Centre, Mohs surgery is primarily used for selected skin cancers of the face and neck, where achieving both complete removal and preservation of healthy tissue can be particularly important.
Is Mohs Surgery Used for Basal Cell Carcinoma?
Yes. Basal cell carcinoma (BCC) is one of the most common skin cancers treated using Mohs surgery.
However, having a BCC doesn’t automatically mean that Mohs surgery is necessary.
Standard excision and other treatments can be very effective for many lower-risk BCCs. Mohs may be considered when characteristics of the cancer make precise margin control particularly valuable—for example, certain BCCs on the face, cancers that have returned following previous treatment, or lesions with more aggressive features.
Skin Centre uses standard surgical excision for many low- to moderate-risk BCCs while considering Mohs for higher-risk cancers and those in cosmetically sensitive locations.
Is Mohs Surgery Used for Squamous Cell Carcinoma?
Mohs surgery can also be used to treat squamous cell carcinoma (SCC).
As with BCC, the appropriate treatment depends on the individual cancer.
Standard surgical excision is widely used for SCC and can be appropriate for many cancers with a relatively low risk of recurrence or spread. Mohs may be considered for selected higher-risk SCCs, recurrent cancers or those occurring in anatomically sensitive locations.
Your dermatologist will consider the characteristics of the tumour and your individual circumstances when recommending treatment.
Is Mohs Surgery Always Better Than Standard Excision?
No. Mohs surgery is a specialised treatment, but not every skin cancer requires it.
For a straightforward, low-risk skin cancer in an area where sufficient surrounding tissue can be removed safely, standard surgical excision may be entirely appropriate.
In fact, Mohs generally isn’t recommended for small, uncomplicated, low-risk BCCs or SCCs on the trunk and extremities of otherwise healthy people because the additional benefits of the specialised procedure may not justify its use in those circumstances.
Mohs is most valuable when its precise margin control and tissue preservation offer a meaningful advantage.
The decision is therefore not simply about which procedure is “better”. It is about which treatment is most appropriate for that particular skin cancer.
Why Does Preserving Healthy Skin Matter on the Face?
Imagine removing a skin cancer from the middle of someone’s back compared with removing one from the edge of an eyelid or the side of the nose.
An additional few millimetres of tissue can have very different implications.
On the face, preserving healthy tissue can help provide the surgeon with more options when reconstructing the area after the cancer has been removed. This can be important for both appearance and function.
Mohs surgery is designed to identify where cancer cells remain rather than repeatedly removing a wider area of normal-looking tissue.
At Skin Centre, the operating dermatologist examines the removed tissue on site. If residual tumour is found, additional tissue is taken specifically from the affected area. Once the margins are clear, reconstruction can begin.
What Happens After Mohs Surgery?
Once microscopic examination confirms that the cancer has been removed, attention turns to repairing the wound.
The appropriate method depends on the size, depth and location of the surgical site. Some wounds can be closed directly with stitches, while others may require a skin flap or skin graft. Occasionally, allowing the wound to heal naturally may be appropriate.
For more complex cases, another surgical specialist may sometimes be involved in reconstruction.
Because the final size of the wound isn’t always known until all cancerous tissue has been removed, reconstruction is planned once the Mohs stages are complete.
What Happens During Mohs Surgery?
Mohs surgery at Skin Centre is performed under local anaesthetic as a day procedure.
The visible tumour is initially removed with a narrow margin. The tissue is carefully mapped, colour-coded, prepared in Skin Centre’s on-site laboratory and examined microscopically.
If the margins are clear, no further cancerous tissue needs to be removed.
If cancer cells are detected at a particular margin, the surgeon returns to the corresponding location and removes another small amount of tissue. That specimen is then examined again.
The process continues until the margins are clear.
This means a Mohs appointment can take considerably longer than a standard excision, as there are periods of waiting while tissue is prepared and examined. However, this careful examination is central to the precision of the technique.
How Do I Know Which Skin Cancer Surgery I Need?
There isn’t one treatment that’s right for every skin cancer.
Your dermatologist may consider factors such as:
• Whether the cancer is a BCC, SCC or another type
• Where it is located
• Its size and depth
• The subtype and other pathological features
• Whether its borders are clearly defined
• Whether it has previously been treated
• Whether it has returned
• The importance of preserving surrounding tissue
• Your general health and individual circumstances
For many skin cancers, standard excision is an effective treatment. For selected cancers—particularly higher-risk cancers in sensitive areas of the face and neck—Mohs surgery may offer important advantages.
Mohs Surgery in Tauranga
Skin Centre provides Mohs micrographic surgery in Tauranga from its dedicated day surgery facility.
Our Mohs surgeons remove the cancer and examine the tissue microscopically on site, allowing any remaining cancer to be precisely located before additional tissue is removed. Once the margins are clear, the wound can then be reconstructed.
Skin Centre has extensive experience in Mohs surgery and operates an internationally accredited Mohs Micrographic Surgery fellowship training programme.
If you have been diagnosed with a skin cancer on your face or neck, your dermatologist can determine whether Mohs surgery, standard excision or another form of treatment is appropriate.
Frequently Asked Questions
Is Mohs surgery better than standard excision?
Neither treatment is universally better. Standard excision is highly appropriate for many skin cancers, while Mohs offers particularly precise margin control and tissue preservation for selected higher-risk cancers and cancers in sensitive locations.
Does every basal cell carcinoma need Mohs surgery?
No. Many BCCs can be successfully treated with standard excision or other treatments. Mohs is generally reserved for cases where factors such as location, recurrence risk or tumour characteristics make its advantages particularly valuable.
When is Mohs surgery recommended?
Mohs may be recommended for certain aggressive, large or recurrent BCCs and SCCs, as well as cancers in locations where preserving healthy tissue is particularly important, such as the nose, eyelids and ears.
Why is Mohs surgery commonly used on the nose?
The nose has limited spare tissue and is both functionally and cosmetically important. Mohs allows the surgeon to carefully trace the cancer while attempting to preserve as much unaffected tissue as possible.
Can Mohs surgery treat squamous cell carcinoma?
Yes. Mohs can be used for selected SCCs, particularly those considered higher risk, recurrent or situated in sensitive anatomical locations.
Does Mohs surgery leave a scar?
Mohs surgery is still surgery, so a scar should be expected. However, preserving healthy tissue can reduce the size of the surgical defect compared with unnecessarily removing additional uninvolved tissue. Reconstruction is planned according to the location and size of the final wound.
How many layers are removed during Mohs surgery?
There is no predetermined number. Tissue is removed and examined in stages until microscopic examination shows that the margins are clear of cancer.
Are you awake during Mohs surgery?
Generally, yes. At Skin Centre, Mohs surgery is performed using local anaesthetic, so the treatment area is numbed while you remain awake.
How long does Mohs surgery take?
The duration varies because each layer must be processed and examined before the surgeon knows whether another stage is necessary. Patients should therefore expect periods of waiting between stages.
What happens if cancer is found after the first layer?
The surgeon uses the Mohs map to identify where cancer cells remain and removes additional tissue specifically from that area. The new tissue is then examined, and the process continues until the margins are clear.
Can skin cancer return after Mohs surgery?
No skin cancer treatment can guarantee that a cancer will never recur. Mohs is valued for its comprehensive microscopic margin examination and high cure rates for appropriately selected skin cancers. Ongoing skin surveillance remains important following a skin cancer diagnosis.
Do I need a referral for Mohs surgery in New Zealand?
If you have already been diagnosed with skin cancer and haven’t previously been a Skin Centre patient, a referral may be required before your surgery can be booked. Skin Centre also accepts enquiries regarding assessment and second opinions.
If you have been diagnosed with facial skin cancer and would like to understand your treatment options, contact Skin Centre Tauranga to discuss whether Mohs micrographic surgery may be appropriate for you.