Information on mohs surgery


The principles of Mohs surgery was developed by a general surgeon, Frederic E. Mohs. This is a microscopically controlled surgery used to treat common types of skin cancer. During the surgery, after each removal of tissue and while the patient waits, the tissue is examined for cancer cells.

Mohs surgery, also referred to as Mohs micropgraphic surgery is a precise surgical technique used to treat skin cancer. During Mohs surgery, thin layers of cancer-containing skin are progressively removed and examined until only cancer-free tissue remains.

The removed tissue is processed immediately by the Mohs surgeon in a Mohs histological laboratory on site, while the patient returns to the ward or waits in a waiting room.  The specific method of processing allows tissue slides to be produced that shows the whole, complete cut surface around the tumour. These slides are then examined by the Mohs surgeon and any remaining tumour will be indicated very accurately, also including the exact area on the tumour wound where tumour is still present.

The patient then returns to the day theatre or procedure room and the process is repeated, but only on the area of the remaining tumour, leaving the healthy tumour-free part of the wound untouched.

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

Yes. Following a biopsy, your skin cancer may no longer be visible. However, more tumour cells may remain in the skin that are not visible with the naked eye and can continue to grow if they are not removed. In other words what appears to be a biopsy removed tumour will in all likelihood reappear and will then require more extensive surgery. Tumours, left untreated, have the capability to spread further into the skin and (although rare) cause damage to nearby organs and lymph nodes.

Mohs surgery has the highest success rate. Larger cancers, cancers with more aggressive growth patterns, cancers recurring following previous treatment, incompletely removed cancers, or cancers involving vital areas such as nose, ears, lips and eyelids 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 tumour 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.

An alternative is to have a pathologist on-hand in theatre to perform a few random tissue sections to assist the surgeon in determining if the tumour is fully removed.  Although it improves on the cure rate of a “blind” excision, the whole cut surface is not evaluated but only random areas, therefore tumour can still be left behind.

The Gold Standard surgical method worldwide for the most effective removal of skin cancer is Mohs surgery.  With this technique, performed in most cases under a local anaesthetic, the tumour is removed with a thin layer of surrounding healthy tissue.

Although Mohs surgery tends to have the highest cure rate (99.5% for new skin cancers & 95% for recurrent skin cancers), unfortunately no cancer treatment or surgery has a 100% cure rate. A skin cancer treated with Mohs surgery may (very seldom) recur or a new cancer may arise in the same or adjacent area after Mohs or other surgery. Some skin cancers are more aggressive than others and need additional treatment and closer follow-up. Follow-up appointments with your referring dermatologist are very important, especially in the first few years after surgery. 

There might be some short-lived local discomfort involving swelling and bruising post-surgery. Recovery time is generally minimal.
Depending on the size of the defect it may take 4-6 weeks for the wound to heal completely.
To have the fastest healing time and achieve the best cosmetic result, your Mohs wound will likely require stitches. You will return to the wound care sister in approximately 7-14 days to have your stitches removed.

If you have completed treatment, follow-up visits with your referring dermatologist at regular intervals are very important. People who have had skin cancer are at high risk for developing another skin cancer in a different location, so close follow-up is of utmost importance.

It’s also very important to curb sun exposure as far as possible and vigilantly applying sun block with a high SPF when your skin is exposed to the sun as the sun can increase your risk of new skin cancers.

Today, Mohs surgery has come to be accepted as the single most effective technique for removing Basal cell carcinomas and Squamous cell carcinomas (BCCs and SCCs), the two most common skin cancers.  Lentigo Maligna (melanoma-in-situ), can be treated with a variation of the Mohs technique as well.

Too much unprotected exposure to ultraviolet (UV) radiation from sunlight or tanning beds and lamps are the main contributing factors to skin cancer. Even though fair skinned people who easily sunburn, doesn't tan much or at all, with natural red or blond hair are more at risk to develop skin cancer, skin cancer can affect anyone, both men and women.

A Basal cell carcinoma is the most common type of skin cancer and its appearance is often a small "pearly" bump that looks like a flesh-coloured mole or pimple that doesn't go away. Sometimes these growths can look dark or you may see shiny pink or red patches that are slightly scaly.

Basal cell carcinomas hardly ever invade or spread to the lymph nodes.

A Squamous cell carcinoma is the second most common type of skin cancer and its appearance is often a hard, scaly bump or scaling patch and may be mistaken for a wart or patch of dry skin.

Squamous cell carcinomas can occasionally spread into the lymph nodes and internal organs.  An increased risk of spread is also seen in patients who are immune-suppressed, such as organ transplant patients.

Yes, the referring or treating doctor will decide on whether Mohs is the correct method of treating when it comes to melanomas, the most aggressive skin cancer of all. In most instances Mohs is only used to treat an early malignant melanoma or melanoma in-situ (lentigo maligna), meaning a melanoma that is not invasive yet. When treating melanoma, the Mohs surgeon uses a modified type of Mohs surgery called staged micrographic excision. The patient will wait longer for the results as the formalin fixed histology blocks are sent for special staining to a pathology laboratory. It is not possible for the Mohs surgeon to look at the removed skin and know right away whether the excisional margins still contain residue cancer cells. More time is needed as the tissue is sent for special staining. If you have staged micrographic excision, the Mohs surgeon will remove the visible skin cancer and a thin layer of healthy skin around it. The patient will then be discharged with a dressing on the wound. Once the Mohs surgeon receives the special staining histology result it is then that the patient learns whether more skin must be removed (residue malignancy in histology blocks) or the final closure of the defect can be performed (no residual malignancy in histology blocks).
Lip cancer often looks like a flat or slightly raised whitish discoloration/mouth sore that won’t heal.

Mohs surgery is typically used to treat skin cancer, specifically basal cell carcinoma and squamous cell carcinoma. These types of cancer are usually found on the face, ears, neck, scalp, and hands, and have a high likelihood of reoccurrence. Mohs surgery is a specialized technique that allows for the precise removal of cancerous tissue while minimizing the removal of healthy tissue. This helps to ensure that all of the cancerous cells are removed and reduces the risk of recurrence.

Yes, Mohs micrographic surgery can be done on the eyelid to remove skin cancer. It is a specialized surgical technique that is used to remove skin cancer, particularly basal cell and squamous cell carcinomas, while preserving as much healthy tissue as possible. The removal of eyelid skin cancer is typically performed by a dermatologist or a plastic surgeon who is specially trained in Mohs surgery. The procedure is done under local anesthesia and typically takes several hours. Recovery time can vary depending on the size and location of the cancer, but it usually takes several weeks for the treated area to heal.



Step-by-step guide on the flow of the Mohs Surgery and Reconstruction process.
Indepth guidance of the do’s and don’ts before and the day of your surgery.
More information regarding the surgery and anaesthetics. Important information for post surgery and the scar.


Forms to download, complete and bring along to your
consultation or day of surgery - GAUTENG BRANCH

Forms to download, complete and bring along to your
consultation or day of surgery - WESTERN CAPE BRANCH


The Mohs Micrographic Surgery Process: Information Video To Patients