MOHS Surgery

Mohs Micrographic Surgery is a treatment for some types of skin cancer- most often a type called basal cell carcinoma (rodent ulcer).

How is Mohs surgery done?

1. The skin is made completely numb using a local anaesthetic injection. The visible cancer is removed and the specimen examined under a microscope to see if there is anything left. This takes around 45-60 minutes. You will be asked to sit in the recovery area while you are waiting.
2. A diagram (a “Mohs map”) of the removed specimen is drawn. The microscope check will show if the cancer has been completely removed. If there is any cancer remaining, it is carefully marked on the Mohs map and tells the surgeon precisely where he/she needs to go back to take further specimens.
3. If more specimens are needed we will bring you back into theatre and take these and then once more check under the microscope. This cycle is repeated until the cancer has been fully removed.

How long does Mohs surgery take?

Mohs surgery takes several hours. Because no one can tell how big a cancer will be and what the size of its roots are, we ask you to be prepared to stay with us the whole day (0830-1730).

What are the benefits of Mohs surgery?

Mohs surgery is different from other forms of surgery in that it allows the immediate and complete microscope examination of the specimen. It is not possible for a surgeon to see the roots of a skin cancer under the skin surface without a microscope.

Mohs surgery gives the best chance of cure for non-melanoma skin cancers compared to all other treatments- even if the skin cancer has grown back following previous treatment.

Mohs surgery is also very valuable for preserving normal skin around important sites such as the nose, lips, eyes or ears and keeping the wound as small as possible.

Are there any risks or complications?

1. Scarring – like any form of surgery, Mohs surgery will leave a scar. Whilst we don’t expect an ugly scar, it won’t be invisible. Because Mohs surgery will result in the smallest possible wound, it gives the best chance of a cosmetically good repair and scar. Scars generally become less apparent as time goes on, initially settling over 2 – 4 weeks but giving the best results after 3 – 6 months. Generally after 3 weeks make-up can be applied over the wound/scar.
2. Pain – most patients do not experience significant pain and regular Paracetamol is usually all that is required after Mohs surgery.
3. Bruising/swelling – you will probably have some bruising or swelling around the wound especially if the surgery is done close to the eyes.
4. Bleeding – the wound will be clean, dry and dressed before you leave the department. We will tell you what to do if bleeding occurs when at home – this is rare. Generally you will apply pressure to the wound and follow specific wound care advice (see separate booklet)
5. Wound infection – the risk of a wound infection is low (generally less than 5% ({1 in 20 patients}). You will receive a separate wound care advice leaflet regarding signs to look out for wound infection.

How do I prepare for surgery?

We advise you get a good night’s rest before your surgery. You can normally eat and drink as usual on the morning of your surgery unless you are going elsewhere to have the repair in which case you will have normally been advised if you will need a general anaesthetic and need to starve.

If you are taking any medications, continue to take them unless told otherwise by your consultant. If you are taking any of the medicines or herbal preparations listed below please let us know unless they have already been discussed with you in clinic:

Aspirin
Clopidogrel (Plavix)
Warfarin
Non-steroidal drugs (NSAIDS such as Brufen, Naproxen, Voltarol)
Propanolol
Herbal preparations such as ginger, gingko or garlic remedies

These medicines will make you bleed more during and after the surgery and in some circumstances we will ask you to stop them for the procedure but you will be specifically advised of this – please do not stop unless asked to do so.
Mohs surgery is usually done on the face. If you wear spectacles or contact lenses, please bring these with you. The dressing may prevent you wearing your spectacles initially.

You are welcome to bring one friend or relative with you and you may want to bring a book or magazine with you to occupy your time whilst you are waiting for your slides to be processed and examined. We will provide tea and coffee. You can bring food and snacks to eat through the day or there are shops within the hospital. You will also need to ask someone to drive you home or take a taxi home after your surgery is complete. You will not be able to take public transport or drive yourself home.

Who will look after me whilst I’m having Mohs surgery?

There is a team of highly experienced Mohs nurses that will be responsible for your care throughout your stay as well as your surgeon. They will be available to support you through your stay and can answer any questions you may have.

Are there any alternatives to Mohs surgery?

There are 2 main alternatives to Mohs surgery: Radiotherapy (x-ray treatment) and removal of the skin cancer in the standard way without guidance of the microscope checks.

The different treatment options will normally have been discussed with you at your consultation. Not all treatment choices are suitable or possible for your particular skin cancer and they do not generally offer as high a cure rate as Mohs surgery.

Is there a chance Mohs surgery won’t work and the cancer might come back?
No treatment for skin cancer is 100% effective. Skin cancers can grow back after any type of treatment, but the risk is much lower following Mohs surgery. Mohs surgery offers the best cure rate for basal cell cancer compared with all other skin cancer treatments. The risk of a BCC returning after Mohs surgery is around 1-2% (1 or 2 in 100 patients) for a basal cell carcinoma that has never been treated before and around 6-8% (6 to 8 in 100 patients) for basal cell carcinomas that have grown back after treatment for example with standard surgery or radiotherapy.

How will my wound be repaired after Mohs surgery?

Mohs surgery results in a surgical wound the size of which reflects the true size of the skin cancer. Mohs surgeons have extensive training in wound reconstruction and plastic surgery and in most cases the Mohs surgeon will perform the wound repair. There are generally 3 ways to repair a wound:

1. Allowing the wound to heal naturally without additional surgery. This is normally only possible in certain sites.
2. Closing the wound directly with stitches.
3. Using a skin graft or skin flap to repair the wound. Some patients will need to be transferred to other hospitals for their repair by eye surgeons, ENT surgeons or plastic surgeons. If this applies to you, it will have been discussed with you in clinic in advance. Unless you are being transferred to another hospital you will normally be able to go home the same day. You will have a dressing over your wound that will stay in place for 2 – 7 days depending on the repair and may be quite large and bulky.

Most patients return to the Everything Skin Clinic to have their sutures removed one week later. In most cases you will feel quite well after 48 hours though may not wish to return to work for 1 week when the sutures have been removed.
Each case will be different and we will advise you when you can return to work. At 6 weeks the wound will be reviewed by a specialist nurse and skin care/sun protection will normally be discussed.

What happens after I have gone home?

Even though the operation is performed under local anaesthetic you may feel quite tired afterwards and you should plan a more restful 2 days or so after surgery.

Is there anything I can do to help myself?

If you smoke you should avoid smoking for at least 3-4 days before and after surgery as smoking slows down the wound healing process. Similarly, try and avoid alcohol for 3 – 4 days before and after surgery as this can make your wound bleed more.

What if I think there is something wrong when I get home?

We have a telephone helpline service 01615091294. Out of hours please use the emergency GP services, minor injury unit or accident and emergency department.

Where can I find out more about Mohs surgery?

We would advise you not to “Google” Mohs surgery on the internet as you may see incorrect details or overly dramatic pictures. Instead please refer to the following 2 approved websites:

1. The New Zealand association of Dermatologists website dermnetnz.org
2. The American College of Mohs surgery website www.mohscollege.org

Here are some pictures of skin defects after cancer surgery and results after treatment.