15 Cryosurgery

Cryosurgery is the most commonly performed dermatologic procedure in the United States. There are many different ways to achieve cold temperatures, but clinically, the end result is to freeze the fluid in cells, which causes crystals that damage the cells, resulting in tissue destruction. Different cell types are destroyed at different temperatures (see Table 15-1). Melanocytes are relatively fragile causing the tendency for hypopigmentation with their death. Cartilage and bone are most resistant to freezing and other cells are in between.

TABLE 15-1 Key Events during Freezing Including Cell Death

Temperature (°C)


+11 to +3 65% of capillaries and 35% to 40% of arterioles and venules develop thrombosis.
−0.6 Freezing begins to occur in tissue.
−4 to −7 Melanocytes die.
−15 to −20 100% of blood vessels develop thrombosis.
−20 Cells in sebaceous glands and hair follicles die.
−21.8 Ice crystals theoretically form in the tissue (the eutectic temperature of sodium chloride solution).
−20 to −30 Keratinocytes and malignant cells die.
−30 to −35 Fibroblasts die.
−50 to −60 All cells die including cartilage cells.

Source: Adapted from Vidimos A, Ammirati C, Poblete-Lopez C. Dermatologic Surgery. London: Saunders; 2008; Table 8-3.

Cryosurgery is an easily mastered technique that is extremely useful for treating benign and premalignant lesions. In experienced hands cryosurgery is also a valuable technique for treating small, nonaggressive nonmelanoma skin cancers (NMSCs).


Cryosurgery is most often used to treat actinic keratoses and benign conditions. Table 15-2 provides recommended freeze times and margins of freeze for benign conditions (using liquid nitrogen with an open spray technique). Table 15-3 gives recommended freeze times and margins of freeze for vascular conditions (using liquid nitrogen with a closed probe or an open spray technique). Table 15-4 lists recommendations for treating premalignant and malignant conditions (using liquid nitrogen with an open spray technique). Details on how to perform these procedures follow.

Cryosurgery: Principles and Getting Started


TABLE 15-6 Factors That Affect the Freezing of Tissue


Key Principles

Rate of tissue freezing Rapid freezing causes more cell death. In the open spray technique, this is influenced by the rate of liquid nitrogen spray to the skin (aperture and configuration of the spray conduit).
Rate of intermittent spraying

Halo diameter The wider the halo, the deeper the freeze at the periphery of the lesion.
Distance of spray tip to tissue The closer the tip is to the tissue, the colder the tissue may become because air is not as good a conductor as tissue.
Tissue temperature Final tissue temperature of less than −30°C will kill malignant cells.
Duration of freezing

Rate of thawing Slow thawing causes more cell death.
Repetition of freeze/thaw cycles

Source: Adapted from Vidimos A, Ammirati C. Poblete-Lopez C. Dermatologic Surgery. London: Saunders; 2008; Table 8-2.

Cryosurgery Methods

Many different techniques are used to perform cryosurgery. The most common ones are listed in Table 15-7, which explains how the cryogen is applied and its temperature.

TABLE 15-7 Forms of Various Cryogens and Temperatures



Temperatures (°C)

Liquid nitrogen Open spray, closed probes and CTA
Tissue temperature is less cold if delivered with CTA
Nitrous oxide in tank Closed probes on special gun −89
Solidified CO2 in tank Closed probes on special gun −79
CryoPen Refrigerated closed probes −75
Verruca-Freeze (chlorodifluoromethane and propane) Chemical spray into cones or disposable buds with evaporation producing the cold −70
Wartner (dimethyl ether and propane) OTC foam applicator for warts only −57
Histofreezer (dimethyl ether and propane) Application is via disposable 2- and 5-mm buds −55

Liquid Nitrogen

Most dermatologists and many primary care providers have access to liquid nitrogen. It is the gold standard for cryosurgery. Various cryoguns are marketed that efficiently and effectively deliver the liquid nitrogen to the skin at the coldest temperatures.

Liquid nitrogen is stored in dewar containers ranging in size from 5 to 50 L. The nitrogen may be withdrawn using a ladle, a valve system, or a withdrawal tube (Figure 15-1). The withdrawal tube is the most simple and efficient way to extract liquid nitrogen from your storage container.

For those clinicians who are still working with cotton-tipped applicators (CTAs) and liquid nitrogen in a cup, it is possible to do cryosurgery on benign and premalignant conditions. This method does not get cold enough for treating cancer or most vascular lesions. Dip the CTA into the liquid nitrogen and then touch the CTA to the lesion to be treated. The CTA can be unwound a bit and rewound to make a smaller point, or loose cotton from a cotton ball can be wrapped around the CTA for larger lesions to maintain the freezing temperature longer.

A more time-effective and more efficacious approach is to use a cryogun (Figure 15-2). Once filled, the unit can be used to treat many patients rapidly. The spray method allows the clinician to reach tissue temperatures of up to −196°C while the CTA is not likely to get below −20°C. Although there is a cost involved in the purchase of a cryogun, these units can last a clinician’s full career and pay for themselves very quickly. The reimbursement for cryosurgery is excellent for only a few minutes of your time.

Michael D. Bryne developed the first handheld spray device using liquid nitrogen for medical use in 1968. His family continues to run the Brymill Corporation, which sells the most widely used cryoguns. The variety of cryoguns available from Brymill include (Figure 15-2):


Wallach makes the UltraFreeze Liquid Nitrogen Sprayer, which comes in 500- and 300-mL sizes. Whatever cryogun you use, it helps to have an assortment of apertures and tips. The tips that are available for the Brymill cryoguns include:

Long 20-gauge bent spray with blue cover. This longer tube (3 inches) with an 80-degree angle attenuates the flow of the liquid N2 (LN2) so that the spray is less shocking to the patient (Figure 15-5). This is good for children and adults who fear this therapy. It also allows for pinpoint accuracy on smaller lesions. It can be helpful for treating anogenital condylomas because it allows the clinician to be further from the lesions being treated.

Shorter (1.5 inches) 20-gauge bent spray (metallic color). These have similar benefits to the long blue tube but with less attenuation of flow (Figure 15-5). They have a 45-degree angle at the end. This type of tip has one advantage over the long blue tube: it is less likely to become temporarily blocked up with repeated use. Both bent sprays can be rotated 360 degrees for greater precision when treating hard-to-reach lesions.

Closed probes are useful on vascular lesions to compress the lesion and freeze it simultaneously (Figure 15-7). Closed probes come in many sizes and shapes, ranging from 1 to 6 mm and 1 to 2.5 cm in diameter. The probes are available in round flat shapes, conical and spherical shapes, and shapes for use on the cervix. The liquid nitrogen is vented out a plastic tube so that no spray touches the patient. The spray freezes the probe tip for direct application to a lesion. One method to avoid the probe sticking to the skin is to freeze the probe before applying it to the patient. The closed probes have a “low” infection risk since there is no breach of the patient’s skin. Cleaning of the closed probes can be done with an alcohol wipe prior to use.

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Mar 12, 2016 | Posted by in General Surgery | Comments Off on Cryosurgery

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