MOHS Micrographic Surgery to Treat Skin Cancer

​​This is a specialised form of skin cancer surgery and is also called Mohs’ surgery after the doctor who developed it. Your surgeon first removes the visible portion of your tumour, and then removes a further layer of tissue that may have cancer cells. This tissue is processed in the laboratory and then examined under a microscope while you are still in the dermatology unit. If cancer cells are seen, another layer of tissue is removed and examined. This is repeated until all the cancer cells have been removed.

Your doctor may have recommended Mohs’ surgery because:

• your tumour has returned
• your tumour was incompletely removed
• your tumour is located on your eyelids, nose, ears or lips
• your tumour edge is not well defined
• your tumour may be of the aggressive type

Conventional surgery relies on the surgeon being able to see the extent of the cancer, which can either lead to a large wound and scar if too much healthy tissue is removed, or the cancer remaining or returning if too little tissue is removed. Micrographic surgery maximises the chances that your tumour will be completely removed, while minimising the amount of surrounding normal skin needed to be taken away.

​​Your doctor has recommended that this is the most appropriate treatment for you. Any alternatives will have been discussed at your consultation. If you have further questions please see the contact details below/overleaf. If your skin cancer is not treated, it will continue to grow and may require more aggressive treatment in the future.

The letter accompanying this leaflet contains information about how to prepare for your surgery. Please make sure you read this carefully. Please do not wear any make up or jewellery on or near the site of your surgery. Shower and wash your hair on the day of your surgery before you come. If your doctor has not given you any specific instructions, have your usual medication and breakfast before coming.

​​If you decide to go ahead with this surgery, you will be asked to sign a consent form. This confirms that you agree to have the procedure and understand what it involves.

​​There are several stages to Mohs’ surgery. First, your doctor will inject the area where your tumour is, with a local anaesthetic. This numbs the area, so you will not feel any pain during surgery. It will not put you to sleep, so you will remain awake throughout the surgery. If you are particularly anxious, we can give you a mild sedative to help you relax. Please discuss this with the doctor. We may also use anaesthetic eye drops if your tumour is near your eye.

Once the anaesthetic has taken effect, the visible (also called the clinically evident) part of the tumour will be removed, along with a small 1-2mm margin of normal skin. The tissue will then be processed and prepared so that your surgeon will be able to look at it under a microscope to check for cancer cells. This takes about 60-75 minutes. A temporary dressing will be applied to your wound and you will be asked to sit in the waiting area.

If cancer cells are present in this tissue, you will be brought back into theatre for more tissue to be cut out and examined under the microscope. This will be repeated until all the tumour cells have been removed.

​The local anaesthetic lasts for about 2 hours, and can be ‘topped up’ if needed. Because of the nature of this surgery, we are unable to tell you exactly how long your surgery will last.

Once all the tumour cells have been removed, there are several options for repairing your resulting wound. These will be discussed with you in more detail before your surgery. Your wound may be:

• closed by the team who performed the micrographic surgery immediately after the tumour has been removed;
• dressed and then repaired by a plastic surgeon at a hospital chosen by our surgeon;
• left to heal normally; or
• repaired at another hospital. In this case, we will renew your dressing before you travel to your referring hospital. We will also give you a letter from our doctors to hand to your surgeon when you arrive at your referring hospital.

Your doctor will explain the potential risks for this type of surgery with you in more detail, but complications include:

• Bleeding at the site of the tumour.
• Pain. The local anaesthetic should last until you return home. Aspirin free pain relief (such as Paracetamol) should relieve any discomfort. The doctor or nurse caring for you can give you more advice.
• Nerve damage. Although your surgeon will try to avoid this, nerves can occasionally be damaged during surgery, leading to a numb area of skin. This is usually temporary.
• Infection at the wound site. You will be given instructions on how to care for your wound to minimise this risk.
• Scarring. You will have a scar after the surgery. The doctors use closure techniques to minimise the appearance of this. Scars will fade over time.

​​Before you leave the hospital, please make sure you have been given information about how to look after your wound at home. You will probably need to rest after the surgery for about 48 hours. If you work, we recommend that you take at least 2 days off after the surgery. We will give you more advice on the day of your surgery.

You will have a follow up appointment with the team that repaired your wound. If your follow up is with us at National Skin Centre, we will usually see you one week after your surgery to check that your skin is healing well and to remove any stitches you may have. If there are any changes to this, you will be advised on the day of your surgery. We usually see you again approximately 3 months after your wound has healed.​