Cryotherapy for actinic keratoses
Liquid nitrogen cryotherapy is usually the first-line treatment for actinic keratoses. It is also used to treat small seborrhoeic keratoses, and primary superficial basal cell carcinomas (BCCs) at low-risk sites (ie on areas other than the face).
Avoid cryotherapy if the diagnosis is uncertain, and avoid prolonged cryotherapy on the lower legs, where healing is poor.
Liquid nitrogen is the preferred cryogen and is applied with a cotton-tipped applicator or a spray device. Exposure times to liquid nitrogen vary depending on the type, site, and thickness of the lesion. For detailed advice on cryotherapy, including techniques and recommended exposure times for different types of lesions, see this Australian Family Physician guide.
Patients should be warned to expect inflammation after the treatment. See Caring for skin after liquid nitrogen treatment for printable patient information on cryotherapy aftercare.
The cosmetic outcome after cryotherapy is usually satisfactory, but patients (especially those with dark skin types) should be warned of the risk of hyperpigmentation (usually temporary) and hypopigmentation (often permanent). In patients with certain skin types (eg dark skin types) or lesions on certain areas of the body (eg upper lip, back of hands), prolonged cryotherapy can cause permanent atrophic or hypertrophic scarring, or permanent depigmentation.
Liquid nitrogen is used to treat a range of skin lesions (eg seborrhoeic keratoses, solar or actinic keratoses, some nonmelanoma skin cancers, warts). It rapidly freezes the skin, producing a superficial destruction of the skin lesion.
Day 1 after liquid nitrogen treatment
The treated area becomes red and swollen. A blister may develop, and occasionally fills with blood. It is best to leave blisters alone, but if a blister is uncomfortable or extending, you can lance it with a sterile needle to deflate the blister.
Days 2 and 3 after liquid nitrogen treatment
The treated area becomes weepy. If weeping is mild, leave the skin open to the air—you can safely wash the area with soap and water. If weeping is excessive, cover the area with a dressing.
Days 3 to 4 after liquid nitrogen treatment
The treated area stops weeping and a scab forms. The scab stays for up to a week, and then the area should heal without a mark. Occasionally the healed skin is darker or paler than before—this is usually temporary, but can be permanent.