Quick answer: Mohs micrographic surgery is a precise, tissue-sparing technique for removing certain skin cancers, mainly basal cell and squamous cell carcinomas. The surgeon removes the cancer layer by layer and checks each layer under the microscope during the same visit, continuing until no cancer cells remain. In Singapore it is carried out by trained dermatologists or Mohs surgeons, often at centres such as the National Skin Centre. If you have a new, changing or non-healing skin lesion, have it checked by a doctor.
Not sure which specialist you need?
Message our care team on WhatsApp. Tell us what’s going on and we’ll help you find the right specialist — free, with no obligation.
Chat with our care team on WhatsAppNot sure who to see? Find the right specialist →
In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.
A diagnosis of skin cancer on the face or another sensitive area understandably raises questions about how it will be removed and how the area will look afterwards. Mohs micrographic surgery is one option that combines a very high chance of complete removal with careful preservation of healthy skin. This guide explains what the procedure involves, when it is recommended, and what to expect on the day and during recovery, with Singapore in mind. It is general information and does not replace personalised advice from your own doctor.
What Mohs surgery is
Mohs surgery is a specialised, precise technique used to remove certain skin cancers. Rather than taking out the visible tumour with a broad margin in one step, the surgeon removes the cancer in thin layers. Each layer is mapped and examined under the microscope during the same visit, while you wait. If cancer cells are seen at an edge, the surgeon returns to that exact spot and removes a little more, then checks again. This cycle continues until no cancer cells remain at the margins. Because tissue is taken only where cancer is still present, the technique spares as much healthy skin as possible while achieving a very high chance of complete removal.
Why and when it is used
Mohs surgery is particularly suited to skin cancers in cosmetically or functionally important areas, such as the face, ears, nose, around the eyes and the hands, where preserving healthy tissue matters most. It is also often chosen for larger, recurrent, or aggressive and ill-defined cancers whose borders are hard to judge by eye. The technique is used mainly for basal cell and squamous cell carcinomas. Your dermatologist or Mohs surgeon will consider the type, size and location of the cancer, along with your general health, when deciding whether it is the right approach for you.
How it compares with standard excision
With standard surgical excision, the cancer is removed together with a margin of surrounding skin, and the tissue is sent to a laboratory to be checked later, with results returning after some days. Mohs surgery instead checks the margins during the operation itself. This makes it especially precise and tissue-sparing, and confirmation that the cancer has been fully removed comes on the same day, but the trade-off is that the procedure takes longer while you are at the clinic. Neither approach is universally better; the choice depends on the individual cancer and site.
How to prepare
Before the procedure, tell your doctor about all the medicines and supplements you take, including anything that thins the blood, so they can advise whether to continue or adjust them. Mention any allergies and other medical conditions. It is wise to plan for a long appointment: because the surgery is done in stages with microscope checks in between, you should expect to be at the clinic for several hours, and it can be hard to predict exactly how long. Wearing comfortable clothing, bringing something to read or occupy the waiting time, and arranging for someone to accompany you home can all make the day easier.
What happens on the day
Mohs surgery is usually carried out under local anaesthetic, so the area is numbed but you remain awake. The surgeon first removes the visible cancer and a thin surrounding layer, which is then processed and examined under the microscope. If cancer is found to remain at an edge, more tissue is taken from that precise location and checked again. This is repeated as many times as needed until the margins are clear. Between stages you wait with a temporary dressing in place. Once no cancer cells remain, the wound is repaired or reconstructed, often on the same day; in some cases the surgeon may arrange for reconstruction by another specialist, depending on the size and site of the wound.
Recovery and the wound
After the wound is closed, you will be given instructions on how to care for it, including keeping it clean, changing dressings, and managing any discomfort. Some bruising, swelling and tenderness around the area are common in the early days and settle with time. A scar is expected wherever skin is cut, but wounds from Mohs surgery generally heal well, and the appearance often continues to improve over the months that follow. Your doctor will arrange follow-up to check healing and, importantly, to keep an eye on your skin over the longer term.
Benefits
The main advantages of Mohs surgery are its high cure rate and the maximum preservation of healthy tissue. Because the margins are examined completely during the operation, the surgeon can be confident the cancer has been removed before the wound is closed, which is especially valuable for cancers in delicate or visible areas and for those that have recurred or have unclear borders.
Risks
As with any skin surgery, there are some risks. These include bleeding, infection, and scarring, and sometimes numbness or altered sensation near the wound, which may be temporary or, less often, lasting. Rarely, further treatment may be needed. Your surgeon will discuss the risks relevant to your particular cancer and its location before you agree to proceed.
After skin cancer: staying sun-safe and skin checks
Having had one skin cancer means you are at higher risk of developing another, so ongoing sun protection and skin awareness are important. In Singapore’s strong, year-round sun, seek shade during the middle of the day, wear a wide-brimmed hat and protective clothing, and apply a broad-spectrum sunscreen to exposed skin. Get to know your own skin and check it regularly, and attend the follow-up and skin surveillance appointments your doctor recommends. Report any new, changing or non-healing spot promptly.
When to see a doctor
After the procedure, seek medical care if you notice signs of a wound infection, such as increasing pain, redness, warmth, swelling or discharge, or if you develop a fever, and get urgent help for bleeding that does not stop with gentle pressure. More generally, any new, changing or non-healing skin lesion should be checked by a doctor. Do not try to diagnose skin changes yourself; a dermatologist can examine the area and advise on what, if anything, is needed.
Common questions
Will I be awake during Mohs surgery?
Yes. It is normally done under local anaesthetic, so the area is numbed while you stay awake and comfortable.
Why does it take so long?
The waiting comes from processing and examining each layer of tissue under the microscope before deciding whether more needs to be removed. This careful checking is what makes the technique so precise.
Will I have a scar?
Any surgery that cuts the skin leaves a scar, but Mohs surgery is designed to remove as little healthy tissue as possible, and the wound usually heals well over time.
Is Mohs surgery suitable for every skin cancer?
No. It is used mainly for certain basal cell and squamous cell carcinomas, particularly in delicate areas or when a cancer is large, recurrent or has unclear borders. Your doctor will advise whether it suits your situation.
What happens if cancer is still found at the edges?
The surgeon simply removes a little more tissue from that exact spot and checks again, repeating until the margins are clear before closing the wound.
Related guides
Sources
- National Skin Centre
- HealthHub
- American Academy of Dermatology
- NHS
Disclaimer: This guide is for general information only and does not replace professional medical advice, diagnosis or treatment. Always consult a qualified doctor or dermatologist about your own skin and any procedure. If you have signs of a wound infection or bleeding that will not stop, seek medical care promptly.