Cryotherapy is a technique that uses an extremely cold liquid or instrument to freeze and destroy abnormal skin cells. The technique, also called cryosurgery, has been in use since the turn of the century, but modern techniques have made it widely available to dermatologists and primary care doctors.
Cryotherapy can destroy a variety of skin growths ranging from non-threatening warts to basal cell and squamous cell cancers.
There are three main techniques. In the simplest, usually reserved for wartsand other non-threatening skin growths, the doctor will dip a cotton swab orother applicator into a cup containing a "cryogen," such as liquid nitrogen,and apply it directly to the skin growth to freeze it. At a temperature of -320°F (-196°C), liquid nitrogen is the coldest cryogen available. Thegoal is to freeze the growth as quickly as possible, then let it thaw slowlyfor maximum effect. A second application may be necessary depending on the size of the growth. In another technique, a small amount of cryogen is sprayeddirectly onto the growth. Freezing may last from 5-20 seconds. A second freeze-thaw cycle may be required. Sometimes, a small needle connected to a thermometer is inserted into the growth to ensure it is cooled sufficiently to guarantee maximum destruction. In a third option, the cryogen is circulated through a probe to cool it. The probe is then brought into direct contact with thegrowth to freeze it. This can take two to three times longer than the spraytechnique.
Cryotherapy is not recommended for certain areas of the body because of the dangers of destroying surrounding tissue or unacceptable scarring. These areasinclude: skin that overlies nerves, the corners of the eyes, the fold of skin between the nose and lip, skin surrounding the nostrils, and the border between the lips and the rest of the face. Suspected cases of malignant melanoma(a cancer of pigmented skin cells) should not be treated with cryotherapy, but should be removed surgically. Similarly, basal cell or squamous cell tumors that have reappeared at the site of a previously treated tumor should be surgically removed. If it remains unclear whether a growth is benign or malignant, a tissue sample should be removed for analysis (biopsy) before any attempts to destroy it with cryotherapy. Care should be taken in people with diabetes or certain circulation problems when cryotherapy is considered for growthslocated on their lower legs, ankles, and feet. In these patients, healing can be poor and the risk of infection can be high.
Patients will experience some pain at the time of the freezing, but local anesthesia is usually not required. The doctor may want to reduce the size of certain growths, such as warts, prior to the cryotherapy procedure, and may have patients apply salicylic acid preparations to the growth over several weeks. Sometimes, the physician will lightly pare away some of the tissue.
Redness, swelling, and the formation of a blister at the site of cryotherapyare all expected. Wounds on the head and neck may take four to six weeks to heal, but those on the body, arms, and legs can take longer. Some patients experience pain at the site following the treatment. This can usually be eased with acetaminophen (Tylenol), though in some cases a stronger pain reliever may be required.
Cryotherapy poses little risk and can be well-tolerated by elderly and otherpatients who are not good candidates for other surgical procedures. There issome risk of scarring, infection, and damage to underlying skin, tissue, andnerves, but these risks are generally minimal in the hands of experienced users of cryotherapy. Lightening or darkening of the skin may also occur.
Cryotherapy boasts high success rates in permanently removing skin growths; even for squamous cell and basal cell cancers, studies have shown a cure rateof up to 98%. For certain types of growths, such as some forms of warts, repeat treatments over several weeks are necessary to prevent the growth's return.