Cryotherapy is a treatment technique whereby liquid nitrogen which has a temperature of -196 degrees Celsius, is applied on to a lesion. Dermatologists refer to this as “freezing” a lesion as we are in effect inducing frostbite in a controlled manner. We are aiming to cause “necrosis” or “death” of skin cells in order to remove specific lesions.
Cryotherapy is a valuable tool for us as dermatologists as it allows us to treat a wide variety of skin lesions fairy simply. These can include benign lesions such as warts, molluscum contagiosum and seborrheic keratoses and even pre-malignancies such as actinic keratoses. The various techniques of cryotherapy are also varied and can range from applying the liquid nitrogen with a cotton bud to the use of a spray device called a cryo-gun. Although there is slight local pain felt, cryotherapy does not normally require a local anaesthetic, and the procedure itself lasts a matter of seconds; the precise time depends on the thickness and size of the lesion. The frozen skin becomes white and takes one to two minutes to thaw back to normal skin temperature. Your doctor may suggest that the process be repeated once the skin has thawed.
Following treatment with cryotherapy, the skin becomes red and swells and a scab will form. With a deeper freeze, blisters are produced. The length of time whereby the scabs remain is dependent on many factors but as a general rule, the scabs remain for around 5-7 days on the face, two weeks on the torso, hands and arms and three weeks or even longer on the lower legs. This is because of the relatively poor blood supply to the lower limbs. For this reason, we will be more conservative about using this modality of treatment on the lower legs.
The risk of treatment with liquid nitrogen is that it can permanently damage the pigment cells resulting in white spots where it was applied. To avoid this undesirable complication, we will always err on the side of a more conservative treatment and rather follow-up a few weeks later with a second treatment if necessary. We will advise you to keep the treated areas moist to speed up the healing process using an occlusive ointment. If at any time you are concerned about the treated areas, please do not hesitate to call the practice and arrange a pop-in visit.