Mohs surgery involves a surgical excision of the tumour and a small area of surrounding skin leaving as much healthy tissue as possible in tact.
Skin cancer is caused by the uncontrolled growth of abnormal skin cells which triggers mutations or genetic defects that can cause tumours. The main cause of skin cancer is exposure to the sun’s ultraviolet light but age is a contributory factor with only one in three people diagnosed with melanoma being under 55-years-old.
The advantage of Mohs surgery is that all excised tissue is examined under the microscopic as part of the surgery so the surgeon knows exactly how deep the skin cancer goes rather than having to estimate.
The instant feedback allows for the removal of all the cancer cells while sparing as much normal tissue as possible.
The progressive procedure involves removing one thin layer of tissue at a time which is then checked to the margins for cancer cells. If they are present, the procedure is repeated until a final clean tissue sample is examined.
The elimination of guesswork with precision techniques provides the best therapeutic and cosmetic results. Standard surgery involves removing the visible cancer affected skin and margin of healthy skin at the same time. But sometimes the borders are hard to define so a generous margin of healthy skin is removed.
Mohs surgery is particularly effective on the most common skin cancers, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).
BCCs, which often look like open sores, red patches or shiny bumps are the most frequently occurring form of skin cancer and can be diagnosed by sight. SCCs is the second most common type of skin cancer in the UK. Both are caused by prolonged exposure to ultraviolet rays.
Dermatologists at St. John’s have Mohs as a specialty and are proficient and experienced in performing the procedure.
It is done on an outpatient basis in an operating room close to a laboratory to enable easy and swift examination of tissue layers. The procedure normally takes about four hours.
The areas of skin are outlined with a special pen and are then injected with a local anaesthetic so there is no discomfort for the patient.
The first layer is removed with a scalpel and sent for examination and it may take an hour before results are available to indicate if further layers need to be removed.
Depending on the area of skin removed, the wound could require stitches or be left to heal on its own but in some cases a skin graft from another part of the body may be needed.
Mohs surgery has a success rate of 98% or higher but follow-up consultations are advised.