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Cryotherapy is a common office procedure, and is the mainstay for the treatment of many benign and precancerous lesions. Liquid nitrogen, which has a boiling point of −196°C (−321°F), is the coldest and most commonly used cryogen. A 30 second spray of liquid nitrogen will result in tissue temperatures of −25°C to −50°C (−13°F to −58°F). Most benign lesions will be destroyed at a tissue temperature of −20°C to 30°C.8
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The use of cryosurgical devices (eg, CRY-AC, CryoPro, FrigiSpray) with a spray tip and fingertip trigger is a safe and accurate way to use liquid nitrogen. Lesions commonly treated with cryotherapy include actinic keratoses, viral warts (human papillomavirus and molluscum contagiosum), seborrheic keratoses, and skin tags.
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The patient should be informed that cryotherapy is painful during and sometimes for several minutes after the procedure. Erythema, bullae, and sometimes hemorrhagic bullae may develop. Hypopigmentation may be more prominent in individuals with darker skin types. Scarring can occur if the freezing extends into the dermis.
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Position the nozzle of the spray tip 1 to 1.5 cm from the lesion to be treated.
Spray the lesion until a 2 mm rim of frost develops around the lesion and then continue spraying for 5 to 30 seconds depending on the thickness, diameter, and location of the lesions (Figure 7-5). For larger lesions this can be done in spiral or paintbrush pattern. Approximate freeze times vary.
Actinic keratosis: 5 to 20 second freeze cycle, depending on the location and size of the lesion9
Seborrheic keratosis: 5 to 10 seconds for thin, flat lesions8
Warts: 10 seconds. Plantar warts may require a second freeze cycle10
Skin tags: 5 seconds8
Cover the eyes, nostrils, and exterior auditory canal with gauze or cotton if cryosurgery is done near those sites. Care should also be taken not to deeply freeze the skin near the digital nerves on the medial and lateral aspects of the fingers and toes.
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Video demonstrations of cryotherapy can be found at www.LangeClinicalDermatology.com.
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Curettage and Electrodesiccation
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Curettage and electrodesiccation is a commonly used procedure for the treatment of seborrheic keratosis, certain types of viral warts, pyogenic granulomas, and superficial basal cell carcinomas. In the hands of an experienced clinician, it also can be used for some small nodular basal cell carcinomas.11 Electrodesiccation without cautery can be used on small skin tags and cherry angiomas. Electrodesiccation should not be used on any patient with an implantable cardiac device. If needed, a battery-operated, disposable heat cautery device could be used in these patients.
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The patients should be informed of the risks of the procedure that include bleeding, infection, scars, and hyperpigmentation or hypopigmentation.
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Equipment needed in addition to the standard tray is as follows:
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Fox round or oval curette, sizes 3 to 5 mm are most commonly used.
Monoterminal electrodesiccation unit.
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The steps for curettage and electrodesiccation are presented in Table 7-6.12
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Wound Care and Follow-Up
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Wound care and follow-up are dictated by the type of procedure that was performed. Many patients have the false notion that air drying the wound will promote a more rapid healing response. In general, a clean wound will heal more rapidly and with less scarring if a good moisture barrier is maintained throughout the healing process. A firm pressure dressing is helpful for any full thickness procedure, and should be left in place for 24 to 48 hours.
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Surgical Complications
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Excessive bleeding during a procedure is disconcerting to both the clinician and the patient. Firm application of pressure for several minutes often controls bleeding. Identification of the bleeding vessel and compression while performing cautery is usually very effective. An assistant who can hold pressure and wick away blood that is obscuring the surgical field is critical in this process.
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A second concern is postprocedure bleeding. As the vasoconstriction due to epinephrine wears off, bleeding may occur minutes or hours later. Even a small amount of blood may cause anxiety in a patient. The patient should be advised of this possibility and given clear instructions to apply firm constant pressure for a minimum of 15 minutes. If the bleeding does not stop after this process, medical care should be sought either with the clinician who performed the procedure or at an urgent care facility. The development of a hematoma under a closed wound if large and firm warrants evacuation, cautery, and resuturing of the wound.
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Part of patient screening should include questions regarding the presence of a pacemaker or implantable cardiac defibrillator. The use of monopolar electrodessication has a risk for triggering or damaging these devises. Electrocautery (heat cautery) and bipolar cautery should be used instead.
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Whenever the skin barrier is breached, infection is possible and prophylactic antibiotics may be indicated. Infection is more likely in wounds that have been exposed to the environment, or in certain body areas such as distal extremities and areas near body orifices.
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Depending on the wound location and the exposure risk, topical or oral antibiotics individually or in combination may be appropriate. Cephalexin is often prescribed for wounds of the lower extremity due to a higher risk of infection. When to use prophylaxis and what type of prophylaxis to use is often a topic of debate among experts and its specific application is beyond the scope of this text.
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Some nonprescription topical antibiotic ointments (eg, bacitracin, neosporin) have a significant risk of allergic contact dermatitis. Whenever a wound becomes more inflamed with the use of a topical antibiotic, an allergic contact dermatitis must be considered. Mupirocin ointment is less likely to cause allergic contact dermatitis.
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Separation of the wound can occur if the strength of the healing scar is not adequate at the time of suture removal. Excisions at sites with a poor vascular supply, such as the leg, will often require a significantly longer healing period of up to an additional week before suture removal. Infection can also lead to an increase in wound pressure and loss of wound integrity. Dehisced wounds can be resutured several days following a closure if the wound is cleaned and any risk for infection is addressed. The reclosed wound may require a drain if infection is present or anticipated. Resuturing should not be performed if an abscess is present. If the dehiscence occurs more than 24 hours after the excision, the reepithelialized tissue from the center of wound may need to be removed. A dehisced wound can also be left to heal with secondary intention, but this may result in a significant scar.