In a recent report, cryotherapy was the second most common in-office procedure after skin excision. The mechanism of destruction is necrosis, which results from the freezing and thawing of cells. Treated areas re-epithelialize.
Side effects are usually minor and short-lived.
Cryotherapy has been used by dermatologists since the turn of the century. After the development of the vacuum flask to store sub-zero liquid elements such as nitrogen, oxygen and hydrogen, the use of cryotherapy increased dramatically. By the 1940s liquid nitrogen became more readily available and the most common method of application was by means of a cotton applicator. In 1961, Cooper introduced a closed-system apparatus to spray liquid nitrogen. In the late 1960s metal probes became available.