Dr Koh Hong Yi is a qualified dermatologic and Mohs micrographic surgeon. He was trained in Ninewells Hospital, Dundee, which is one of the largest Mohs surgery centre in the UK. Dr Koh established the Mohs micrographic surgery service at Singapore General Hospital (SGH). He currently performs Mohs surgery in his private practice, and also at SGH where he is a visiting consultant.
Mohs micrographic surgery (Mohs surgery) is named after Dr Frederic E Mohs who invented this technique in the 1930s. The technique for Mohs surgery has been revised over the years and is globally the gold standard treatment for skin cancers. Compared to traditional wide excision surgery, Mohs surgery delivers a higher rate of removing all cancer cells and preventing cancer recurrence, while keeping the wound as small as possible. A smaller wound allows faster healing and results in a smaller scar. Mohs micrographic surgery is the recommended treatment for skin cancers on the face (where most skin cancers arise), for large skin cancers and cancers on areas where tissue preservation is critical, such as the genitals, hands and feet.
Mohs micrographic surgery are mostly performed by fellowship-trained dermatological surgeons. In Mohs surgery, cancer tissue is removed layer by layer and examined under the microscope on the same day. Further tissue is only removed if remaining cancer cells are seen. This means healthy, cancer-free tissue is not sacrificed. After the doctor is satisfied that no more cancer cells are seen, the wound can be closed. The dermatologic surgeon is also trained to perform reconstruction of the wound, using various methods such as the skin flaps or grafts.
Mohs micrographic surgery is usually performed under local anaesthesia. Fasting is not required. The doctor will have gone through the patient's medications and advised which may be continued on the day of surgery. The visible skin cancer is marked out and removed; this is the first layer of Mohs surgery. This tissue is immediately sent to an attached lab and processed. This procedure involves sectioning, staining and mounting tissue onto microscope slides, and may take up to 2 hours depending on the size and thickness of the tissue. Meanwhile, the wound is dressed, and the patient may leave the operating room and wait at the adjoining waiting area with family members and have refreshments.
After the tissue is prepared, the dermatologic surgeon will look at the slides personally to check if all cancer cells from the patient have been removed. If there are still cancer cells seen, the patient will be brought back to the operating room for a bit more skin tissue to be removed. This process of tissue removal and testing is repeated until the doctor is satisfied that no more cancer cells remain. Each cycle is called a Mohs stage, and the majority of Mohs surgeries can be completed within 3 stages.
After cancer clearance is complete, the dermatologic surgeon will discuss with the patient the best form of reconstruction. Small wounds may be closed by stitching up the wound or by letting it heal naturally. Larger wounds may be closed using a skin graft or flap, and will be performed by the dermatologic surgeon on the same day.
Mohs micrographic surgery is usually performed for skin cancers on cosmetically sensitive areas such as the face, and where the risk of cancer recurrence is high. Examples where Mohs surgery is recommended include:
Our specialists provide a comprehensive range of dermatological treatments, personalized to suit your unique requirements.
At TSN Dermatology, we only recommend what we feel is necessary and most appropriate for your condition. Surgical and non-surgical treatment options will be shared for you to consider. Our fees are transparent, and you only pay for what you need.
Aesthetic dermatology is focused on restoring beauty to the skin, recreating a youthful appearance, and ultimately helping our patients feel happier and more confident in their own skin. At TSN Dermatology, we believe in listening empathetically to your concerns, and providing sincere recommendations on how to help you achieve a healthier look. We employ both […]
Our Singapore-based dermatologists have a wide breadth of experience, having trained in renowned centres such as the Massachusetts General Hospital (United States), St John’s Institute of Dermatology (United Kingdom) and Australia. Our specialists keep up to date with the latest developments in medical dermatology and are opinion leaders and invited speakers in their respective subspecialties.
In Mohs surgery, skin tissue is removed layer by layer, and only tissue that has been affected by skin cancer is removed. This ensures minimal sacrifice of normal skin, resulting in a smaller wound and scar.
The way the removed tissue is processed is also different from traditional surgery using frozen section. The entire margin of a Mohs layer is examined completely by the Mohs surgeon, reducing the risk that any cancer cells are left behind in the body. This contrasts with traditional frozen section, where a sampling technique is employed and not all the removed tissue is examined for residual cancer cells.
Most insurance plans typically provide coverage for Mohs micrographic surgery when it is used to treat skin cancer. However, it is essential to check with your insurance provider and our surgeon to understand your specific coverage and any potential out-of-pocket costs.
No, there are several treatments available for skin cancer which provides patients with a range of options. Some of these options include excision, radiation therapy, and topical medications.
The decision on which treatment to pursue is influenced by factors like the type and stage of the cancer and your individual health considerations. As such, you have different paths to explore with your doctor or skin specialist when discussing your treatment plan.
Mohs micrographic surgery is generally not very painful. You will be under the care of a skilled surgeon who will administer local anaesthesia during the procedure, so you shouldn’t experience significant pain. Afterwards, you might have some mild discomfort, which is typically easily manageable with over-the-counter pain relievers. Your surgeon will ensure your comfort throughout the process.
