By Gary M. White, MD
Typical blister after freezing an AK.
Cryotherapy is a very common procedure in dermatology. It is used as a destructive modality to removed actinic keratoses, warts, seborrheic keratoses etc. Liquid nitrogen is sprayed on the skin, causing an immediate freezing of the tissue. (Liquid nitrogen has an extraordinarily low boiling point of -196 degrees Celsius, or -321 degrees Fahrenheit.) The formation of ice within the cells causes them to die in the ensuing days. A blister forms, which turns into a crust and ultimately falls off in 7-14 days. Epidermal cells are preferentially affected compared to dermal cells which is why this modality is excellent for lesions limited to the epidermis. Melanocytes are particularly sensitive to the cold and thus freezing in darker-skinned patients runs the high risk of leaving white spots.
Patients with Fanconi anemia, cryoglobulinemia, poor peripheral circulation and Raynaud phenomenon may develop severe blistering in response to cryotherapy.
Using a tongue blade when freezing about the eye is helpful.
Either a Q-tip or a Cry Ac may be used.
Freezing here was a little too aggressive!
A hemorrhagic bulla
Necrosis of tissue, forming a scab, which will eventually fall off.
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