Overview
This is a cancer of the pigment cells (melanocytes) in the skin, and is a dangerous type of skin cancer.
Causes
Excessive exposure to the sun and a history of sunburns are predisposing factors.
It often presents as a dark brown or black skin growth or ulcer. It may look like ordinary moles. But unlike the common mole:
- it grows more rapidly
- its surface may have varying shades of colour
- its surface may be thick and irregular
- its margin may be irregular
- it may show features of change over time
Melanomas may occur spontaneously, or they may arise from a pre-existing "normal" mole. People born with large moles (giant congenital nevi) or have positive family history of melanoma are at increased risk. Melanoma is more common among Caucasians and less common in Asians and people with a darker skin type. It can occur on any site, including the nails, the palms and soles.
Prevention
- Sun exposure has been shown to be an important factor in the development of many skin tumours. Avoidance of long hours of intense sun exposure may help to decrease the risk of skin cancers. It is advisable to use proper sun-protection (e.g. sunscreens, umbrellas, hats) when going out in the sun.
- Avoid smoking.
Detection & Treatment
Treatment
The most common form of treatment of a malignant skin tumour is excision, a process which involves removing the entire skin lesion. In certain situations whereby complete excision may not be feasible, other forms of therapy such as cryotherapy, topical therapy (creams), photodynamic therapy (PDT) or radiotherapy may be used.
What is micrographic surgery (MOHS)?
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.
What happens during MOHS surgery?
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.
What happens after the MOHS procedure?
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.
What are the risks of MOHS surgery?
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.
What do I need to do after I go home?
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.
Will I have a follow-up appointment?
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.
Care Management
Follow up
After removal of a malignant skin tumour, patients will need to be followed up regularly by their doctors for a few years. This is to look out for any recurrences of the skin tumour that may occur. It also gives the doctor a chance to assess whether new skin tumours have developed in other areas.
In certain situations (e.g. In advanced disease, or if the skin tumour has spread to involve the lymph nodes or other organs), some patients may need to be further evaluated and managed jointly with an oncologist cancer specialist.
Specialties & Services

