Mohs Micrographic Surgery

Mohs micrographic surgery is a specialised surgical method for removing certain types of skin cancer developed by Dr Frederic Mohs in the 1930s.

Normal operations for treating skin cancer have involved removal of the affected area along with an area of healthy skin around and below it (margin) in order to ensure that the entire cancer has been fully removed. Once removed, the affected skin is sent to the laboratory for examination by a pathologist who looks at tissue cells under the microscope and confirms the diagnosis and whether the operation has been successful or not. It can take 2 weeks for the report to become available. If the report shows that the cancer has not been fully removed, a further operation may be necessary.

In Mohs micrographic surgery, the skin cancer is removed, a thin layer at a time with a very small margin of healthy skin around it. Each layer is immediately checked under the microscope by the surgeon. A further layer is taken from any areas in which the tumour remains, if necessary, until all of the skin cancer has been removed in entirety. This results in removal of as little healthy skin around and below the cancer as possible, which keeps the wound as small as possible, giving a better outcome. This method makes it almost certain that the skin cancer is fully removed on the day of the procedure.


Photodynamic therapy (PDT) is a technique for treating pre-cancerous skin lesions and sun-damaged skin.

PDT can be used to treat various skin conditions including:

  • Superficial basal cell carcinomas
  • Bowen’s disease (in-situ squamous cell carcinoma).
  • Actinic (solar) keratoses

PDT is an outpatient procedure. It takes several hours to complete. In the first step a cream is applied, containing the photosensitiser, to the area. A dressing will then be applied over the cream and you will be asked to return in 3 hours. This wait is to allow the cream to be absorbed and to be converted into the active chemical by the skin. The cream is then wiped off. A bright red coloured light is then shone onto the area for about 10 minutes. When red light is shone onto skin to which the photosensitising cream has been applied, the photosensitiser is activated. This causes changes in the molecules within the sun-damaged skin cells. These activated molecules kill the cells. Only the area of skin exposed to the red light source will be affected; after the redness clears it should be cured.

After the treatment, a covering will be applied to prevent any further exposure to light.

The short-term side effects of PDT include:

  • Pain. If it is too sore, treatment may be paused for a while.
  • Inflammation. The treated area may initially become pink and puffy: this is normal.
  • Blistering and ulceration.
  • Infection.

5-Fluorouracil (5FU)

5-FU cream is a treatment that destroys sun-damaged cells in the skin whilst preserving the normal healthy skin cells. It is usually prescribed for actinic keratosis and Bowen’s disease.

5-FU cream will cause inflammation consisting of redness, soreness, oozing, crusts and scabs. On completing the treatment this reaction will settle over several weeks. Steroid cream can help settle the inflammation.

In the UK 5% 5-FU cream (Efudix®) and 0.5% 5-FU combined with 10% Salicylic acid (Actikerall®) are available.

If the skin becomes very sore or uncomfortable stop using 5-FU cream. Bathe the area with water, dab the skin dry and apply Vaseline daily. The Vaseline should be newly opened and free from contamination. When the skin settles you can continue 5-FU cream to complete the treatment course.