Traitement du cancer de la peau par chirurgie micrographique de Mohs

Treatment of Skin Cancer with MOHS Micrographic Surgery

Your doctor might have recommended micrographic surgery to take away your skin cancer. This page will try to explain the important things related to this surgery as well as the risks and benefits.

What is MOHS (Micrographic) Surgery ?

Named after the surgeon who developed this technique, MOHS Micrographic Surgery (Frederick Mohs) is a specialized surgical technique which is used for taking out some skin cancers. The surgeon takes away the visible portion of the tumor end then takes additional skin tissue which might contain cancerous cells: this technique is a layer by layer (section by section) procedure. Each section is examined under a microscope while you are still at the center during the procedure. The process is repeated as long as cancerous cells are present.

The reasons why your doctor (physician) may have recommended MOHS surgery are:

• an existing skin cancer has returned
• the tumour was excised, but some cancer cells remain
• your skin cancer is located in a region where skin tissue must be preserved (for examples the face: eyebrows, nose, lips as well as the ears).
• the edges of your skin cancer are blurred (badly delineated)
• your skin cancer type has an aggressive behaviour.

Why should I have MOHS (Micrographic) surgery?

Other surgical techniques to remove skin cancers rely on the eye of the surgeon to delineate its extent. This can lead to large wounds and scars as more skin tends to me removed. Micrographic surgery (MOHS) maximises the chances that your skin cancer will be completely removed and minimizes the quantity of normal tissue removed.

What happens during MOHS surgery ?

• There are different stages

1. Firstly, the surgeon injects local anesthetic to put the treated area to “sleep” and therefore avoid pain during the procedure. The injection will not put YOU to sleep and you will remain conscious during the procedure. If you are very anxious, a light sedative can be given at the same time: please mention this to your doctor. Anesthetic drops may also be used if the tumour is close to the eye.
2. Once the anesthetic has started to take effect, the clinically visible part of the tumour is taken out with a small margin of normal skin tissue. All the taken tissue is then sent to the laboratory where the physician will be able to examine them more closely with a microscope, looking for any cancerous cells. This process takes between 40 and 60 minutes, so that a temporary dressing will be applied locally before waiting in the waiting room (do not forget to bring things to kill time: books…).
3. If cancerous cells are present in the examined tissue, you will go back to the operating theatre and more skin tissue will be taken out and sent for microscopic examination. The process will be repeated as long as  cancerous cells are present.
4. The anesthetic substance injected lasts for about 2 hours and if needed more of it can be injecte during the process. Because of the time umpredictability of this technique, it is not possible to determine the lebgth of the procedure.

What happens when everything has been taken out ?

• When no more cancerous cells are present, different options are available to close the created wound. The options will be discussed in more detail with the physician (dermatologic surgeon) doing the procedure.
• The wound:

1. can be closed by the physicians doing the procedure right after that the skin cancer has been taken out
2. can be covered by a dressing and the wound closed by a plastic surgeon
3. can be allowed to heal on its own

What are the risks ?

• Your doctor (dermatologic surgeon) will explain the potential risks. Complications include:

1. bleeding on the operated area
2. pain: the effect of the local anesthetic should last until you return home. Painkillers (paracetamol…) should alleviate the pain.
3. nerve injury. While your dermatologic surgeon will take all possible precautionry measures, nerves can sometimes be damaged during the procedure, which leads to sensory and motor changes. These effects are usually temporary.
4. infection of the operated are. It is important to follow wound care guidelines following the operation to minimize the risks.
5. scarring. You will get a scar after the surgery when the wound heals. The dermatologic surgeons use wound closing techniques that minimize their size. The size and color (colour) of the scar usually diminish with time.

What must I do when I return home ?

Before leaving the centre where you are having the surgery, make sure that you have obtained all the information on how to take care of the wound at home. You should probably rest for the 48 hours following the procedure. Therefore, if you work, we advise you to take leave for at least 2 days following the surgery.

Post-surgical follow-up

An appointment will be given following the surgery. The appointment is usually one week after to ensure that the skin is healing well as well as to remove eventual stitches. Of course, every case is unique, and doesn’t follow a standard timetable.

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland

National Skin Centre. Singapore