What is Mohs Micrographic Surgery?

There is an epidemic of skin cancer in the world, and South Africa is no exception.  Although the most dangerous skin cancer is malignant melanoma, the most common ones are known as basal cell carcinoma and squamous cell carcinoma, collectively known as non-melanoma skin cancer (NMSC).

These cancers are primarily caused by prior sunburns, and therefore occur on skin previously exposed to the sun.  NMSC is destructive to healthy tissues, and some aggressive forms may even metastasize to the lymph glands and into the body.  With the face being the most common area where they occur, including the nose, ears, lips and eyelids, removing and curing them with the highest degree of certainty, without sacrificing the surrounding healthy tissues is of utmost importance.

Early and very superficial skin cancers can often be treated effectively by dermatologists and other doctors through non-surgical methods.

Larger cancers, cancers with more aggressive growth patterns, cancers recurring following previous treatment, incompletely removed cancers, or cancers involving important cosmetic and functional areas such as the face should be treated with surgery.

Traditional surgery removing the cancer with a wide rim of healthy surrounding tissue has the limitation that it is essentially “blind”, meaning tumor can be left behind, and to reduce that risk, the surgeon often has to sacrifice additional surrounding healthy tissue, leading to larger defects and reconstructions.  Even then, complete tumour removal is at best a calculated guess.

An improvement over the “blind” technique is to have a pathologist on hand in theatre to perform a few random tissue sections to assist the surgeon in determining if the tumor is fully removed.  This technique is expensive in pathologist and theatre time, making it impractical as a routine procedure.  Although it improves on the cure rate of a “blind” excision, the whole cut surface is not evaluated but random areas only, therefore tumour can still be left behind.

The Gold Standard surgical method worldwide for the most effective removal of skin cancer is a technique called Mohs Micrographic Surgery (now performed in Somerset West near Cape Town).  (“Mohs” refers to the surname of the doctor who first practiced it).  With this technique, performed in most cases under a local anaesthetic, the tumor is removed with a thin layer of surrounding healthy tissue.  The removed tissue is then processed immediately by the Mohs surgeon in an on-site Mohs histology laboratory, while the patient returns to the ward.

The Mohs specific method of processing allows tissue slides to be produced that shows the whole, 100% complete cut surface around and underneath the tumour.  These slides are then examined by the Mohs surgeon and will show very accurately any remaining tumour, including the exact area on the tumour wound where tumour is still present.

If a tumour is detected, the patient then returns to the day theatre and the process is repeated, but only on the area of remaining tumour, leaving the healthy tumour-free part of the wound alone. This continues until all margins are confirmed to be clear of tumour.

As soon as the Mohs surgeon confirms the skin cancer to be completely removed, the Mohs or a specialist reconstructive surgeon repairs the defect where the cancer was removed, almost always on the same day.

The result is the highest possible level of certainty that the skin cancer has been completely removed, with the smallest possible defect, making closure of the wound potentially simpler and without fear of any remaining tumour.

This world class treatment is now being offered in Somerset West, only 30 minutes from Cape Town and performed by Dr. Johann De Wet and his team.

A state-of-the-art histopathology laboratory has been established within the theatre complex at Advanced Vergelegen Surgical Centre (Somerset West), making it the first of its kind in the Western Cape.

The Mohs surgery service is supported by a multi-professional team of medical specialists comprising of plastic and reconstructive surgeons, oculoplastic surgeons, head-and-neck cancer specialists and general surgeons specialising in cancer treatment. The vision of the unit is to establish itself as a centre of excellence for skin cancer treatment.

Patients who will benefit from Mohs surgery are those with larger cancers, cancers with more aggressive growth patterns, cancers recurring following previous treatment, incompletely removed cancers, or cancers involving important cosmetic and functional areas such as the face.

Mohs surgery and reconstruction is a same day procedure performed in a day hospital setting and covered by most medical aids. For more information on Mohs Micrographic surgery in Cape Town, please contact us.

What is Mohs Surgery