Urticaire chronique (pour les professionnels)
Cryotherapy on Benign Lesions (liquid nitrogen)(For Professionnals)
Dr Christophe Hsu – dermatologist. Geneva, Switzerland
Cryotherapy (a controlled frosbite) is an effective tool to treat benign skin tumors provided clinical judgment and/or histology exclude a malignant skin condition when excision becomes mandatory. It destroys tissue through freezing which causes intracellular and extracellular ice crystals to form and the vascular stasis causes tissue anoxia and necrosis. In this chapter, we mean cryotherapy with liquid nitrogen which boiling point is at -198.5 degrees Celcius.
If not sure about freeze delivery, use a swab instead of a spray, especially on the face. Some cryosurgeons use probes, but there is a risk of infectious contamination.
As a general rule, two freeze-thaw cycles are needed. This is enough for superficial lesions but warts can be deeper and it is then better to do multiple short freezes.
- Indications (only the benign conditions are listed here):
- acne cysts
- actinic keratosis
- actinic cheilitis
- angioma
- viral warts
- condylomata (genital warts)
- chondrodermatitis nodularis helicis
- dermatofibroma
- Hypertrophic scarring
- keloids
- lentigo (simplex) and freckles
- molluscum contagiosum
- myxoid cyst
- pyogenic granuloma
- sebaceous hyperplasia
- seborrheic keratosis
- Never treat people with cold related conditions such as:
- croglobulinaemia
- cryofibrinogenaemia
- cold urticaria
- Raynaud’s disease
There are side-effects, so apart from having experience in treating a specific lesion, it is always better to undertreat than over treat so as to minimize these risks. Risks include:
- Commonly:
- Pain: strongest upon rewarming (thaw) and minutes after. Richly innervated areas such as eyelids, ears, lips fingers and soles are painful.
- Blister formation: clear fluid or blood tainted.
- Edema and swelling: common on forehead, periorbital region and pernieum.
- Hypopigmentation and Hyperpigmentation. Hypopigmentation occurs if freezing lasts more than 30s. Pigmentation changes more frequent in dark-skinned individuals.
- Hair loss: freeze for less than 30s to avoid it.
- Less commonly:
- Hemorrhage
- Infection: mght be due to redipping swabs or by the use of cryoprobes.
- Sensory change: rarely permanent
- Tendon rupture: can happen when deep freezing of the finger extensors
- Extensive tissue destruction: more likely in damaged skin or when the vascular supply is diminished.
- Scarring: limit freeze times on lips, eyelids, proximal nail folds.
Treatment modalities
- Actinic keratosis:
- freeze for 8 to 20 seconds
- one freeze-thaw cycle
- Common and Plantar Viral wart:
- pare wart
- freeze 10 to 20 seconds (up to 45 seconds if periungal)
- 2 freeze-thaw cycles
- Condyloma Accuminata (Genital warts)
- freeze up to 30 seconds
- Dermatofibroma
- shave excision of the roof
- then base frozen for 30s
- Keloids
- 30-60 seconds
- useful on earlobe
- hypopigmentation and atrophy
- Lentigo and freckles
- 10 second spray
- 1-2mm margin around treated area
- Molluscum Contagiosum
- 10 second spray
- 1-2mm margin around treated area
- Seborrheic Keratosis
- 10-30 second spray
- 2mm margin around treated area
Contributors
Dr Christophe Hsu – dermatologist. Geneva, Switzerland
Bibliography
Cryosurgery for common skin lesions. Treatment in family physicians’ offices. S. J. Wetmore. Can Fam Physician. 1999 April; 45: 964-974
Dermatology Secrets, 3rd edition, Mosby-Elsevier
This advice is for informational purposes only and does not replace therapeutic judgement done by a skin doctor.
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