Mohs Surgery
Named after Dr Frederick Mohs, a professor of Surgery in Wisconsin in the 1940s. who first developed a technique for removing skin cancers and examining their extent microscopically during surgery – hence ‘Mohs Surgery’.
The technique today is performed using frozen sections of skin which are sectioned, stained and looked at under the microscope during the surgical procedure. The tissue sections differ from routine histopathology in that the complete peripheral margin is examined – this is the only way of determining that none of the skin cancer is left behind. By mapping and recording the exact orientation of the tissue samples, the skin cancer is can be removed with minimal loss of normal skin.
What to expect during surgery
The extend of the skin cancer is marked out with a pen, the skin is anaesthetised and this are removed surgically. The wound is dressed with a temporary dressing.
The tissue sample is marked with special coloured inks to orientate upper/lower and right/left edges. The laboratory technician freezed the skin sample, and cuts fine stripes off the outside edge. These strips are stained and looked at under a microscope. This enables the cells in the skin to be seen and any malignant ones identified.
If no skin cancer cells are seen, that means that the skin cancer is fully removed and the patient’s wound is repaired. If cancer cells are seen in one part of the sections, then this area only needs to be removed. The temporary dressing is removed, the wound anaesthetised again and another area of skin removed. This is examined microscopically. This procedure continues until no further skin cancer cells are seen. In most cases only 1-3 stages are required.
The way the wound is repaired depends on the site and size. Sometimes direct suturing is possible. Large wounds will require a skin graft or skin flap.
Who will benefit from Mohs Surgery
Mohs Surgery is recommended for Basal and Squamous cell carcinomas where:
| 1. |
they occur on the face and are large enough to require a skin flap or graft |
| 2. |
they occur at a particularly difficult site, eg around the eyes, nose, lips or ears |
| 3. |
they have reoccurred after previous treatment |
| 4. |
they have indeterminate border or infiltrate deep into the skin. |
The benefit of Mohs Surgery is that it produces the highest cure rate (98%) and it enables the surgeon to preserve as much normal skin as possible. Without the microscopic control, many surgeons removed are large margin of normal skin as a ‘safety margin’.
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