#cryotherapy - freezing to treat benign skin lesions.

Cryotherapy (a controlled frosbite) is an effective tool to treat benign skin tumors when clinical judgment and/or histology exclude a malignant skin condition (malignant lesions must be excised always). It destroys tissue through freezing which causes intracellular and extracellular ice crystals to form; vascular stasis causes tissue anoxia and necrosis. 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:

1. acne cysts
2. actinic keratosis
3. actinic cheilitis
4. angioma
5. viral warts
6. condylomata (genital warts)
7. chondrodermatitis nodularis helicis
8. dermatofibroma
9. hypertrophic scarring
10. keloids
11. lentigo (simplex) and freckles
12. molluscum contagiosum
13. myxoid cyst
14. pyogenic granuloma
15. sebaceous hyperplasia
16. seborrheic keratosis

Never use cryotherapy in people with cold related conditions such as cryoglobulinaemia, cryofibrinogenaemia, cold urticaria and 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:

1. Pain: stronger upon rewarming (thaw) and minutes after. Richly innervated areas such as eyelids, ears, lips, fingers and soles are painful.
2. Blister formation: clear fluid or blood tinted.
3. Edema and swelling: common on forehead, periorbital region and pernieum.
4. Hypopigmentation and Hyperpigmentation. Hypopigmentation occurs if freezing lasts more than 30s. Pigmentation changes are more frequent in dark-skinned individuals.
5. Hair loss: freeze for less than 30s to avoid it.

Less commonly:

1. Hemorrhagea
2. Infection
3. Sensory changes: rarely permanent
4. Tendon rupture: can happen when deep freezing of the finger extensors
5. Extensive tissue destruction: more likely in damaged skin or when the vascular supply is diminished.
6. Scarring: limit freeze times on lips, eyelids & proximal nail folds.