Cryotherapy is a modern therapy for skin treatment that uses a very cold fluid to freeze skin growths and other abnormal cells, which can then be destroyed or removed. This technique is also known as cryosurgery. Even if it was actually discovered since the early 1900s, it couldn't be widely used for a long time. Modern equipment makes it possible for dermatologists or normal doctors to apply it today.

Cryotherapy is very effective against a wide range of localized skin issues. These include benign skin growth like warts but also several types of skin cancer.

The principle of cryotherapy is to use an agent to instantly freeze the abnormal cells. However, in order to kill them properly, it is also important to let them slowly return to their normal state. The body then eliminates the dead cells in a few weeks, if they are located under the skin, just like any debris or impurities. If the diseased cells are killed on the skin surface, the area will be first protected by a scab, which falls off after a few weeks when the repair process is completed. While it is very effective against skin growths, only small ones can be removed using this technique. As long as the growths are localized, they can be eliminated safely, for example skin cancers in early stages.

The most common freezing agent used is liquid nitrogen, although the inert gas argon is also a possible option. Liquid nitrogen boils at -196°C, which makes it extremely cold and well-suited for this purpose. It can be applied in several ways, depending on the nature of the lesion and its location.

Spray guns or cotton swabs are normally used for topical skin cryotherapy. Inside the body, special needles named cryotherapy needles might be required to inject the liquid nitrogen. Another option is the use of a cryoprobe, a small hollow metal tube that allows liquid nitrogen to flow. A specialist is needed to apply this method and he can properly control the flow of liquid. An incision is required to insert the cryoprobe in the skin. However, natural body openings such as the throat, rectum or urethra allow the insertion of flexible tubes. These are named an endoscope, laparoscope or bronchoscope, depending of the location where they are inserted. Doctors then use a CT scan, ultrasound imaging or another similar device to guide the needle or probe to the right location and freeze the target cells with liquid nitrogen.

Cryotherapy can be performed using one of the three main techniques available. Benign skin growth such as warts can be eliminated through the simplest of these techniques. The freezing agent (liquid nitrogen or argon) is stored in a cup. The doctor simply dips a swab made of cotton or another similar applicator into the cup and applies the agent directly on the target skin growth. The skin growth freezes extremely fast but must be allowed to thaw slowly, in order to cause maximum damage to the cells. If the lesion has a larger size, sometimes the procedure must be repeated. Liquid nitrogen is the best cryogen for this purpose, since it is the coldest with a temperature of -196°C.

The second technique uses a device similar to a spray to apply the agent on the growth that has to be eliminated. It usually takes between 5 and 20 seconds until the growth is completely frozen. Large-size lesions sometimes must be frozen and unfrozen a second time. A small needle can be connected to a thermometer and inserted into the growth, if the doctor wants to be sure it is completely frozen. This allows him to ensure that the maximum amount of damage is caused to the abnormal cells.

Another method is to avoid direct contact between nitrogen and the skin and use a probe instead. Circulating nitrogen through the probe cools it to a very low temperature and then it can be used to freeze the skin growth. However, this technique freezes the lesions a lot slower and around twice or three times more time is required.

Treating skin lesions

Cryotherapy is today a routine procedure and is not only used by dermatologists but also by general practitioners and even nurses. It is sometimes applied on the spot, immediately after a consultation, to remove many different types of skin lesions. These include warts, seborrhoeic keratosis (a type of warts only found on adults), actinic keratosis (skin damage from UV radiation) or molluscum contagiosum (can't be removed from children). Verrucas can also be removed in special cases from older kids and adults, only if they are painful or located in sensitive places.

The procedure requires liquid nitrogen to only make contact with the skin for a few seconds. The skin freezes and becomes white but only needs a few minutes to return to the normal temperature. If the growth is larger or very thick, the procedure has to be done one more time. The pain is mild and very limited so anaesthetics are not needed, not even a local one.

The initial side effect can be redness in the area, followed by a blister after a few hours. The location is then covered by a protective scab, which falls in one or two weeks as the skin heals completely. Scabs located on the legs need a longer time to heal. The skin lesion is inspected again at the end and cryotherapy repeated if needed.

What is the purpose of cryotherapy?

Cryotherapy is a very effective procedure that can treat numerous types of skin growths. It can destroy only the abnormal cells by freezing, without any effect on the nearby healthy tissues. Some of the lesions that can be removed by cryotherapy are benign growths, warts, asactinic keratosis and other pre-cancerous lesions as well as several types of cancer such as basal cell and squamous cell cancers.

What are the precautions?

The procedure can't be used in some areas of the skin because it can permanently destroy tissues and cause scarring. These are located in very sensitive places where important nerves are active very close under the skin. Examples include the skin around nostrils, the area between the lips and the nose, eye corners as well as the edge of lips. Malignant melanoma can appear in these locations but it must be removed through conventional surgery instead of cryotherapy. Cryotherapy is also unsuited for basal cell or squamous cell carcinomas that appear in the same place of a former tumour. Surgery is the best choice in those cases.

Sometimes it is not easy to decide if a growth is cancerous or not. Pathologists can remove a small part of the lesion for testing, a procedure known as a biopsy. Only after the results are clear should cryotherapy be attempted. This treatment should also be applied with care when the patient suffers from diabetes or has poor circulation, especially if the growths are located on the feet or lower legs. The healing rate in these cases can be very slow, which greatly increases the risk of infections.

Cryotherapy preparation

Cryotherapy can usually be performed quickly, without much preparation. Make sure to clean the area and dry it well, it doesn't have to be perfectly sterile. Local anesthesia is rarely needed but tell the patient there might be mild and temporary pain when the growth is frozen. In some cases, doctors can prepare warts and other large growths by reducing their size before the procedure. This can be achieved by applying salicylic acid preparations for a period of several weeks before cryotherapy. A curette or scalpel can also be used to surgically remove a part of the lesion in advance.

After cryotherapy procedure

Some side effects are to be expected and the frozen location can become red or swollen. The formation of a blister is quite common after the treatment. Liquids can ooze from the wound for a period between 5 days and two weeks, the wound must be washed three or four times per day until it dries up. The crust or scab that forms at the end will fall off when healing is complete. In some cases, pain can persist in the area after the procedure. This can be treated with Tylenol (acetaminophen) or stronger painkillers.

What are the risks of cryotherapy?

Cryotherapy is a pretty safe procedure and even elders and other vulnerable people can tolerate it, unlike other alternatives such as surgery. There is always a risk of infection, scarring or permanent damage to the deeper layers of skin. However, a well-trained cryotherapy operator can greatly reduce such risks.