Cryosurgery is a frequently performed ablative procedure that is used in the treatment of benign, premalignant, and malignant skin growths. Cryosurgery produces controlled destruction of skin lesions by withdrawing heat from the target tissue. Historically, physicians have used liquid nitrogen applied with cotton-tipped swabs, although modern applications generally use a probe tip containing a refrigerant liquid. Human tissue freezes at -2.2°C, with tissue destruction occurring between -10°C and -20°C. Closed probe systems using nitrous oxide can produce probe tip temperatures in the range of -65°C to -89°C.
Cryosurgery produces an ice ball in the target tissue. The edge of the ice ball only achieves a temperature of 0°C, and this area usually recovers. Cryosurgery should be performed so that the ice ball extends at least 2 mm to 5 mm beyond the edge of the lesion being destroyed. Because ice ball formation is geometric in all directions, the lateral extension of the ice ball from the applicator tip gives a good estimation of the depth of ice penetration into the tissue.
Many clinicians advocate the performance of multiple freezes when cryosurgery is performed. The main advantage of freeze-thaw-freeze technique is that greater cell death is achieved in tissue that has been previously frozen (but would otherwise recover). This advantage can be significant when treating premalignant or malignant lesions or lesions that resist freezing. Caution should be exerted during the thaw phase, because vascular lesions may bleed on thawing.
Cryosurgery generally produces a burning sensation during the treatment, although the discomfort of injected anesthetic often exceeds the discomfort of the procedure. After the procedure, cryosurgery produces anesthesia in the treated tissues. Frozen tissue reacts with peripheral edema immediately after thawing. Subsequent bulla formation and exudation occur before the area heals in a fine atrophic scar within 4 weeks. The technique produces high cure rates with good cosmetic results.
Certain medical conditions can produce an exaggerated tissue response to the freezing of the skin (listed in the Relative Contraindications section). Patients with conditions that produce serum cold-induced antibodies (i.e., cryoglobulins) are at greatest risk for marked skin necrosis.
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INDICATIONS
RELATIVE CONTRAINDICATIONS
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PROCEDURE
Pare down thick, hyperkeratotic lesions that resist cryosurgical treatment. Perform paring with a horizontally held no. 15 scalpel blade using a sawing motion or direct pass through the lesion. Achieve topical hemostasis with an agent such as ferric subsulfate (Monsel's solution) before cryotherapy.
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(1) Pare down thick, hyperkeratotic lesions with a horizontally held no. 15 scalpel blade using a sawing motion or direct pass through the lesion. |
PITFALL: Blood at the surface of the skin acts like an insulator against cryosurgical destruction. Do not perform cryosurgery on an actively bleeding lesion.
Select a cryosurgical tip for the procedure that approximates the size of the lesion being treated.
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(2) Select a cryosurgical tip that is approximately the same size of the lesion being treated. |
PITFALL: Avoid mismatched cryosurgical tips that can result in inadequate or excessive treatment.
A large, flat tip applied over a small lesion produces excessive tissue destruction and potential scarring.
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(3) A large, flat tip applied over a small lesion produces excessive tissue destruction and may cause scarring. |
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Inadequate treatment of warts using a tip that is too small may result in the formation of a ring wart. Formation of a ring wart does not always imply inadequate treatment, because 5% of properly treated warts result in ring wart formation.
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(4) Ring wart. |
Apply water-soluble gel to the cryotip, and place the tip on the target tissue at ambient (room) temperature. Activate the cryogun, causing the gel to turn white. The duration of the freeze depends on the time required to produce a proper-sized ice ball. The edge of the ice ball will recover.
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(5) The duration of the freeze depends on the time required to produce a proper-sized ice ball. |
PITFALL: Use the size of the ice ball to guide the duration of the procedure. Physicians often desire to use freeze times to guide therapy. Freeze times vary substantially because of factors such as the pressure (amount of refrigerant) in the tank, skin or lesion temperature, and thickness of the lesion.
After an adequate freeze has been obtained, deactivate the cryogun, and allow the probe tip to defrost before disengaging the tip from the target tissue.
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(6) After an adequate freeze has been obtained, deactivate the cryogun, and allow the probe tip to defrost before disengaging the tip from the target tissue. |
PITFALL: Do not pull the cryotip off the target tissue before it has defrosted or pull a cotton swab with liquid nitrogen off a mucosal surface before it has thawed. Withdrawal of applicator tips before defrosting often results in the removal or denuding of the tissue surface.
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Allow adequate time for the lesion to thaw before the reapplying cryotherapy. As the tissue thaws, the white ice ball becomes red. An adequate thaw permits fluid and electrolyte shifts in the lesional tissue that enhance subsequent applications of cryotherapy.
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(7) As tissue thaws, the white ice ball becomes red. |
PITFALL: Thawing of vascular lesions, such as cherry angiomas or pyogenic granulomas, may bleed extensively on thawing. Be prepared for this potential bleeding; gauze can be applied using direct pressure, or Monsel's solution can be applied to control bleeding.
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CODING INFORMATION
Destruction performed in certain locations such as penis and vulva can be billed using a specific site destruction code. Specific site codes generally reimburse more than the general codes. Malignant lesion destruction (17260–17286) provides additional reimbursement when cancerous lesions are ablated.
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INSTRUMENT AND MATERIALS ORDERING
Office gun applicators, tank units, and hand-held devices can be obtained from Wallach Surgical, 235 Edison Road, Orange, CT 06477 (phone: 203-799-2000; http://www.wallachsd.com) and from Brymill Cryogenic Systems, 105 Windermere Avenue, Ellington, CT 06029-3858 (phone: 800-777-2796; http://www.brymill.com).
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