Mohs surgery is usually performed under local anaesthetic (an injection is used to numb the skin around the cancer),  but if needed can be under general anaesthetic (with you asleep). The skin cancer is then removed, but unlike conventional surgery for basal cell carcinoma where a wide margin of skin is taken, only a minimal margin of ‘normal looking’ skin is initially taken in Mohs surgery.

The wound is then dressed with a sterile dressing and you return to the ward area. The Mohs surgeon takes the skin specimen into the nearby Mohs lab and processes it to produce slides that can then be checked under a microscope. Mohs maps have also been drawn of where the skin cancer came from.

When the slides are checked, the Mohs surgeon is looking for any evidence of skin cancer that hasn’t been fully removed (skin cancers can have extensions, like roots, that can extend far away from the main cancer, but are not visible by naked eye from the outside of the skin – the only way to see these ‘roots’ is with the microscope). If any is found, then the location can be drawn on the map. The Mohs surgeon can then tell whereabouts on the wound the skin cancer might be.

The skin is then numbed again, and a further thin layer is removed, but only from where the remaining skin cancer ‘roots’ are. The wound is dressed, slides processed and checked, and the process is repeated until the skin cancer has been cleared.

The wound can then be repaired which, depending on the location, size and shape of the wound, may need various reconstructive techniques. These include simple closure (stitching of the wound), moving in skin from nearby (local flap), skin grafting, or even more complex techniques. Occasionally, the wound may be left to heal on its’ own, if it is the right size, shape and location for this.

Often, as the reconstruction is such an important part of the surgery, it is common for a Mohs surgeon to send you to a specialist in Reconstructive surgery, with the reconstruction taking place 1-2 days after the Mohs surgery. Sometimes a Mohs surgeon will be able to reconstruct the wound themselves though, and so can usually perform the reconstruction for you on the same day as your Mohs surgery.