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Cryosurgery refers to the use of extreme cold to destroy cells of abnormal or diseased tissue. The earliest use of a cold refrigerant in medicine is attributed to White, a New York dermatologist, in 1899.1,2 Using a cotton-tipped applicator dipped into liquefied air, he successfully treated warts, nevi, and precancerous and cancerous lesions. In 1907, Whitehouse, another New York dermatologist, reported the utilization of the spray method in the cryosurgical treatment of skin cancers.3
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Cryobiology refers to the study of the effects of subzero temperature on living systems. Tissue destruction from cryotherapy results from direct cell injury, vascular stasis, and the local inflammatory response.
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Rapid freezing of cells causes intracellular ice crystal formation with the disruption of electrolytes and pH changes, whereas slow freezing causes extracellular ice formation and less cell damage. Therefore, tissue effects and cell death are most readily achieved when tissue is frozen rapidly.4
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During thawing, recrystallization occurs when ice crystals fuse to form large crystals that disrupt cell membranes. As the ice melts further, the extracellular environment becomes hypotonic, causing water to infuse into sells a cell lysis.5 The longer the thawing time, the greater damage to the cells because of increased solute effect and greater recrystallization.5
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After freezing, stasis within the vasculature occurs. This loss of circulation and resultant anoxia is a major mechanism of injury from cryosurgery. As the tissue thaws over 0°C (32°F), a brief hyperemic response ensues, with resultant edema and inflammation.
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Liquid nitrogen is the cryogen of choice in dermatology. It is easy to store and use, environmentally friendly, nonflammable, inexpensive, and at –195.8°C (–320.4°F), has the lowest temperature of all the common cryogens, causing rapid freeze of treated tissue.
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Other available cryogens include fluorinated hydrocarbons, solid carbon dioxide, and nitrous oxide (Table 246-1). Fluorinated hydrocarbons are used as topical sprays to provide temporary anesthesia before the removal of skin lesions or the administration of vaccinations. Cryogen spray cooling is also used to reduce the pain of laser surgery and eliminate overheating of the epidermis.6
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Cryosurgery is a destructive modality used to treat benign and malignant skin neoplasms. Several factors, including lesion type, size, depth, border, location, and patient skin type, should be considered when cryosurgery is a treatment choice.
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Absolute contraindications to cryosurgery include lesions that require histopathology for diagnosis and recurrent nonmelanoma skin cancers. Relative contraindications to cryosurgery include patients with cold urticaria, abnormal cold intolerance, cryoglobulinemia or cryofibrinogenemia, or tumors with indistinct borders or darkly pigmented melanotic features.
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Precautions should be undertaken when:
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