Cryotherapy is a method that uses extremely cold liquid, liquid nitrogen, which has a temperature of -196°C, to freeze and destroy skin cells that need removal. It is usually used to remove a variety of non-cancerous or pre-cancerous lesions, such as sunspots (Actinic Keratosis), warts and some early, superficial skin cancers. Lesions suspected of being melanoma must not be treated with cryotherapy. Melanoma must be removed surgically.
The goal of cryotherapy is to freeze the skin as quickly as possible, and then allow it to slowly thaw in order to destroy the affected skin cells. New healthy skin cells will then grow in their place.
Liquid nitrogen is applied on to the skin to destroy the area of skin involved.
Cryotherapy does sting and may be slightly painful at the time of the procedure and for a short time afterwards. The amount of discomfort varies a great deal from person to person. The procedure does not require anaesthesia, as freezing itself has considerable local anaesthetic effect.
After the procedure there may be some redness and swelling, and the area may also blister. Once this blister stage is over, usually within a few days, a crust will form which will fall off in a week or so. Activities such as swimming or bathing should be avoided for at least 3 days but gentle showering is allowed and the area should be kept clean to avoid any possible infection. Infection is, however, rare. Some sores or scabs may persist for as long as a month or two in lesions frozen on the lower leg, as healing at this site is often quite slow.
Well-performed cryotherapy for sunspots usually produces no significant mark on the skin in most people. However, some people are very sensitive to cryotherapy, and they may be left with a pale discolouration of the skin. In most cases the lesion will be removed with the initial procedure. However, in some cases, a second, or even third, treatment may be necessary if the whole lesion has not cleared, especially if it was large or thick to begin with, or if it has recurred.
Skin lesions which survive two or three treatments with cryotherapy usually need to be biopsied, to ensure that they are not skin cancers.