Mohs micrographic surgery is a precise technique that is used to remove skin cancers such as basal cell carcinomas and squamous cell carcinomas. The surgery ensures the complete removal of the cancer cells, with minimum damage to healthy tissue around the cancer.
Mohs microsurgery is particularly useful for skin cancers on the face and hands, where preservation of as much healthy tissue as possible is paramount. The principle is to remove the lesion in thin layers, examining each piece of tissue that’s been taken away under a microscope during the surgery. The surgery is finished only when the surgeon is confident that the entire cancer has been removed. The margin of healthy tissue removed with it is minimised as the edges of the tumour are precisely detected. This means faster healing and less scarring afterwards.
The origins of Mohs microsurgery
The Mohs technique was invented, developed and refined over decades of work at the University of Wisconsin and at Wisconsin General Hospital. Dr Mohs performed the technique for the first time on 30th June 1936 while working from a single room clinic at the hospital; he went on to train doctors across the world in the technique that would eventually bear his name.
The Mohs technique was initially rejected by many surgeons because they were not keen on the idea of having to learn the new skills in histology and slide preparation that are an essential part of the procedure. However, it was embraced by dermatologists, who were already familiar with these procedures.
Dr Mohs technique originally involved using a chemical paste of zinc chloride and bloodroot to cauterise and kill the affected area ready for the surgery. However, in 1953, it is said that he performed a fresh tissue excision by accident, and was so surprised with the enhanced results that he changed his technique. Most chemosurgeons changed to the fresh tissue method soon afterwards as the new method had the benefit of allowing full excision and closing of the wound on the same day.
Improving the technique for Mohs microsurgery
The Mohs surgery technique was improved in the 1970s by Perry Robins, who introduced the idea of using a local anaesthetic and then freezing the excised tissue ready for examination. Although Mohs chemical paste is no longer part of the technique, the term chemosurgery is still sometimes used to refer to Mohs microsurgery.
While Frederic Mohs was the pioneer and lifelong advocate of his famous technique, he has enjoyed the support and inspiration of many leading scientists along the way. These include his original mentor, the zoologist Dr Michael Guyer, Bob Patnaude, his trusted technician of almost 40 years, and Dr Theodore Tromovitch, who published a revolutionary paper on fresh, unfixed tissue excision.
Frederic Mohs died in 2002 aged 92, having dramatically improved the outcome for countless skin cancer patients around the world.
Mohs microsurgery today
Today’s dermatology surgeons have advanced microscopes but the technique is essentially the same. Experience is hugely important – Dr Conal Perrett is one of the UK’s leading experts in Mohs microsurgery and he operates on many cases each month, both in private practice and in the NHS.