What is Mohs surgery?
Mohs surgery is a special and very effective technique for removing skin tumors. The method was developed and first presented by Dr. Frederic Mohs from the University of Wisconsin in 1930, and is now used by doctors all over the world.

Mohs surgery is different from other surgical techniques in that it allows for immediate and complete microscopic examination of the removed tumor tissue and so ensures the full removal of all its roots and branches.  

Likewise, the healing of the surgical wound is usually far more attractive esthetically than other methods. The success rate of this surgery in removing tumors and preventing their recurrence – 99% – is the highest among all current skin cancer treatments.

One doesn’t need Mohs surgery for all types of skin cancers. Mohs is reserved for tumors that have returned after earlier treatment/surgery, tumors that are naturally inclined to have a greater risk of return or tumors located in areas requiring maximum preservation of healthy skin, so that the surgery can ensure full reconstruction without causing any esthetic damage after removing the tumor.

Shaare Zedek has a team of surgeons specially trained to practice Mohs surgery, general dermatology and skin histopathology. They are supported by a skilled staff of nurses, tissue processing technicians and a special laboratory enabling the examination of the tissue in its entirety.

Why remove cancerous skin tumors using Mohs surgery?

Some skin cancers are large and spread throughout the skin away from what we can see on the surface. These tumors are likely to have “roots” in the depths of the skin or along blood vessels, nerves or cartilages. Furthermore, tumors recurring after partial removal are liable to send “branches” deep under the scar formed after the earlier surgery. One of the ‘weaknesses’ of skin cancers is that they are continuous tumors stemming from one cell and all their constituent parts are connected to one another. Mohs surgery capitalizes on this weakness and is specifically designed to trace and remove these cancerous roots completely, thus preventing the recurrence of the tumor.

How should I prepare for the surgery?

1. We recommend resting well the night before your surgery and eating a good breakfast.

2. There is no need to fast on the day of the operation.

3. If the patient is taking prescription drugs, he or she should continue to do so unless told otherwise.

4. Patients taking anti-coagulants (Sintrom, Coumadin, etc.) should consult the doctor before the surgery. It is preferable to switch these drugs with other anti-coagulants that are more short-term, like Clexane for example.

5. There is no need to stop taking drugs containing aspirin or plavix before the operation.

6. You can take Acamol any time before the operation.

7. Patients who know they are likely to suffer from anxiety and are very concerned about the surgery should take light tranquilizers such as Valerian or Rescue drops. If you are very stressed you can take formal prescription tranquilizers.

8. Smokers are asked to refrain from smoking at least 24 hours before surgery (even better would be a break of two weeks beforehand), to enhance the quality of recovery and prevent complications around the surgical wound. If the patient is physically dependent on smoking, there are alternatives such as nicotine patches, ‘Nicorette’ gum, or electronic cigarettes.

What should I bring on the day of the operation?

1. Payment guarantee from your kupat holim or another payment arrangement.

2. A summary of your medical state from your family doctor, detailing background, drugs you may be taking and any known allergies to particular drugs.

3. A referral letter from the doctor that referred you to Mohs surgery.

4. Updated blood test (blood count, coagulation functioning) and ECG results.

5. It is preferable not to put on make-up on the morning of the operation and to wear clothes you don’t mind getting blood-stained.

6. We recommend coming with someone who can stay with you and help you home after the surgery.

7. The average stay in the clinic is 4-5 hours. So to pass the time, bring something to read or to listen to.

8. Write down any questions you may have and ask the doctor/nurse when you register at the desk.

How is Mohs surgery performed?

The operation is performed ambulatorily (ie the patient can walk in and out, with no need for hospitalization) in a designated operating theater. There are three stages involved: 

1. The affected skin is anesthetized using local anesthetic. The visible tumor is removed together with another thin layer of tissue beyond it. The removed tissue is photographed together with the surgical wound and the surgeon prepares a detailed “map” of what the tissue and the wound look like (a Mohs Map.) This stage is usually quite quick and the patient then returns to the waiting room.

2. A sample of the tissue is marked and sent to the laboratory for microscopic testing. This stage takes the most time (40-60 minutes.)

3. The surgeon carefully examines the slivers of tissue under the microscope. This is how all the surgical border of the removed tissue is examined. All the tumor’s roots and branches, if they exist, are identified at this stage and their location is noted on the Mohs Map. If the findings indicate tumor residue beyond the bounds of the removed tissue, the surgeon will use the Mohs Map to locate them and remove further tissue. The surgery will continue through stages 1-3 until the microscopic examination reveals that all tumor tissue has been successfully removed. 


This is how Mohs surgery can leave the smallest surgical wound possible while still removing the maximum amount of cancerous tissue. This method prevents unnecessary removal of healthy tissue and ensures that no parts of the tumor remain in the body.

How long is the operation?

In most cases, the surgery (all three stages) lasts up to four hours. It is impossible to predict in advance how much the tumor has spread, because the branches are often within or under the skin and invisible to the naked eye. In these cases, the surgery may take longer and we recommend that patients free up a full day for the operation and for resting afterwards. 

It is important to realize that the aim of this surgery is to remove the tumor in its entirety. Sometimes this process encounters difficulties that could affect the patient’s functioning or esthetic appearance (for example, nerve damage, crucial structures need to be cut out, etc.) In these cases, the surgeon will stop, explain the situation to the patient and ask for his or her approval before continuing.

What happens after Mohs surgery?

After the tumor has been completely removed, the surgeon will discuss all the options with the patient. These may include:

1. To allow the wound to heal naturally, with no further surgery (this often leads to the best cosmetic results.)

2. Another operation to repair and close the wound immediately after the Mohs surgery.

3. An appointment to close the wound a day or a few days after the original surgery.

4. Referral for further surgery or treatment in another hospital department (Plastic Surgery, ENT, Maxillofacial Surgery, etc.) if necessary.

5. Referral for further treatment in the Oncology Department, if the characteristics of the tumor and the results of the surgery indicate a need for complementary oncological treatment.

Does the surgery leave a scar?

Yes. Every type of surgery leaves a scar. However, Mohs surgery creates the smallest possible wound so the scars are also smaller. It is also impossible – and not sensible – to predict scar size before the tumor is fully removed.

Will the surgery leave me in pain, or cause bruising or swelling?

Most patients do not report significant pain. If you do feel discomfort or pain, it can usually be calmed by taking Acamol/Optalgin/Nurofen. If necessary, the doctor will prescribe stronger drugs. Sometimes there is bruising or swelling, particularly when the surgery is close to the eyes (forehead, cheeks, nose).

Does the surgery involve risks or complications?

The risks and complications possible in Mohs surgery are the same as for any skin surgery. The main ones are:

1. Bleeding – heavy bleeding may appear during the operation following intentional or unintentional damage to a large blood vessel. The medical team will be able to control the bleeding by applying localized pressure, burning blood vessels using an electric device or stitching the affected area. There may be bleeding under the bandage after surgery. The risk of bleeding is mainly in the first 12 hours after surgery and can usually be averted by applying localized pressure. Sometimes, if the bleeding continues, we re-open the wound to identify the bleeding vessels and treat them accordingly.

2. Nerve damage and consequent disorders – not feeling anything around the affected area or inability to perform certain functions. The extent of the damage depends on where the tumor was and how deep it penetrated into the tissue. The surgical borders are likely to include nerves and so sometimes any damage is actually planned. In these cases, the surgeon will explain to the patient that the nerve must be damaged in order to remove the tumor. If the damage is not intended, nerve function is usually restored within a few months of the surgery. In some cases, the damage may be irreversible.

3. Pain – most of the pain during the surgery is a result of the local anesthetic or an insufficient amount of anesthetic. In most cases, injecting more solves the problem. Most patients do not feel any significant pain after surgery and any pains they do have can usually be treated with simple painkillers such as Acamol or Optalgin and pass within a day or two.

4. Infection – Mohs surgery is performed under completely sterile conditions. Having said that, because it is a prolonged procedure during which the patient remains with an open wound or with fairly large areas of tissue or less vascular areas such as cartilages exposed, chances of localized infection increase. Nevertheless, in reality there is a1-2% rate of infection. If the surgeon thinks a particular patient is at greater risk, he or she will give the patient oral preventative antibiotics after the surgery. For all patients, after three days, we recommend smearing antibiotic cream over the stitched area twice a day, until the stitches are removed after about a week.

5. Scars and disfigurement – like any skin surgery, Mohs surgery also ends with a scar. However, our surgeons make every effort to ensure their closure is esthetic and enables normal functioning, without causing disfigurement and always attempting to integrate the scar into the patient’s natural facial features. It is important to note that the size of the tumor, its location and the size of the final wound all influence the surgeon’s ability to achieve esthetic, high quality results.

6. Tumor relapse – Although Mohs surgery is designed to achieve maximum success in removing all the tumor, there are cases in which it is just not possible, due to local topography and/or proximity to vital organs that cannot be damaged. Sometimes, even though the operation has been performed in its entirety, there may be a need for localized further surgery. These cases are rare compared to regular surgery. In cases where the remains of the tumor are suspected to still be present or there are greater chances of relapse, the surgeon will recommend additional treatment, usually radiotherapy and/or a special cream.

What is the recovery procedure after Mohs surgery?

1. After the surgery, you will receive a summary letter with all details of the operation and directives for continued treatment and/or monitoring. You should make an appointment for a check-up and removing the stitches after 7-10 days, as will be noted in the summary letter. For this appointment you will need payment guarantee for a doctor’s visit and stitch removal.

2. If necessary, you will be asked to come in for a weekly check-up for 2-3 weeks after the surgery. In most cases however there is no need for this and it will be enough to come in after 2-3 months.

3. If there are no complications, the wound should heal within 2-3 weeks of the operation. Having said that, the affected area and the scars continue to improve and re-arrange themselves up to two years from the surgery, with more rapid improvement expected over the first few months.

4. Smokers – do not smoke for at least 7-10 days after the surgery. Smoking during this time increases the risk that the skin transplant or the stent used to close the wound will suffer from a low oxygen supply and become damaged so much that the wound will not be able to heal completely. That said, if you want to preserve your skin’s health, it is highly recommended to give up smoking altogether.

5. In the days immediately after removing the bandages and for at least a month or two after that, the patient should always put on sunscreen and avoid – as far as possible – exposing the affected area and scar to direct sunlight.

6. It is important to remember than the main cause of skin cancer is the sun, and smoking is another thing that makes it worse.

7. Patients who have suffered from skin cancer in the past are more likely to develop new tumors and so we recommend putting on sunscreen every day, avoiding sunbathing, and paying regular visits to your dermatologist. 

When should I ask for medical help?

If you have any problems or questions after the surgery, contact your surgeon or your family doctor immediately. The most common problems are:

1. Increasing pain that doesn’t react to normal painkillers.

2. Unusual swelling.

3. Bleeding that doesn’t stop after 20 minutes of localized pressure.

4. A temperature higher than 38°C.