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 warts and other non-threatening skin growths, the doctor will dip a cotton swab or other 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. The goal is to freeze the growth as quickly as possible, then let it thaw slowly...