Cryosurgery/Cryotherapy - Purpose, Procedure, Pros & Cons

Cryosurgery sometimes is referred to as cryotherapy or cryoablation. Cryotherapy is a commonly used in-office procedure for the treatment of a variety of benign and malignant lesions. In one report, cryotherapy was the second most common in-office procedure after skin excision. For external tumors, liquid nitrogen is applied directly to the cancer cells with a cotton swab or spraying device. The mechanism of destruction in cryotherapy is necrosis, which results from the freezing and thawing of cells. Adverse effects of cryotherapy are usually minor and short-lived.

What is the Mechanism of Cryosurgery?

Cryogenic agents: A cryogen is a substance (generally a gas or a liquid) which has the ability to remove the heat from a given target area. The most commonly used cryogens are liquid nitrogen, nitrous oxide and carbon dioxide.

The mechanism of action in cryotherapy can be divided into 3 phases:

  • Heat transfer
  • Cell injury
  • Inflammation

Heat transfer

The mechanism by which cryotherapy destroys the targeted cells is the quick transfer of heat from the skin to a heat sink. The most commonly used cryogen is liquid nitrogen, which has a boiling point of -196°C. The rate of heat transfer is dependent on the temperature difference between the skin and the liquid nitrogen.

When using the spray cryotherapy technique, the liquid nitrogen is applied directly on the skin, and evaporation (boiling heat transfer) occurs in which the heat in the skin is quickly transferred to the liquid nitrogen. This process results in the liquid nitrogen evaporating (boiling) almost immediately.

When using a cryoprobe for cryotherapy, conduction heat transfer occurs where the heat is transferred via the copper-metal probe.

Cell injury

Cell injury occurs during the thaw, after the cell is frozen. Because of the hyperosmotic intracellular conditions, ice crystals do not form until -5°C to -10°C. The transformation of water to ice concentrates the extracellular solutes and results in an osmotic gradient across the cell membrane, causing further damage. Rapid freezing & slow thaw maximize tissue damage to epithelial cells and is most suitable for the treatment of malignancies. Fibroblasts produce less collagen after a rapid thaw. Therefore, a rapid thaw may be more suitable for the treatment of keloids or benign lesions in areas prone to scarring.

Keratinocytes need to be frozen to -50°C for optimum destruction. Melanocytes are more delicate and only require a temperature of -5°C for destruction. This fact is the reason for the resulting hypopigmentation following cryotherapy on darker-skinned individuals. Malignant skin cancers usually need a temperature of -50°C, while benign lesions only require a temperature of -20°C to -25°C.

Inflammation

The last response to cryotherapy is inflammation, which is usually observed as erythema and edema. Inflammation is the response to cell death and helps in local cell destruction. A thorough cryotherapy treatment causes basement membrane separation, which may result in blister formation.

What are pros and cons of cryotherapy:

Pros:

  • Low Cost - This technique is considerably cheaper than other more invasive surgical procedures.
  • Low risk of scarring. Although scarring can sometimes occur, it is not often.
  • Only one application of liquid nitrogen is needed to completely remove the mole, unlike the laser surgery which takes multiple treatments.
  • A small procedure is used on cancerous tumors, therefore cryotherapy may be an effective way of treating cancerous moles. Although it is advisable to consult a doctor before undergoing any treatment.

Cons:

  • Nerve Damage - in extremely rare cases where the nerves are very close to the surface of the skin, damage could occur during the process.
  • Pain - the procedure may cause some stinging although many say that it is not as severe as laser surgery, which is considered to be uncomfortable rather than painful.
  • Blistering - After the surgery blisters may occur over the affected area leading to pain and infection.
  • The treatment is not effective on large flat moles or moles that are deeply rooted beneath the skin.

A dermatologist can better suggest you the type of ablation procedure that can give the best results on the basis of your skin condition. To choose among the best dermatologists/skin care clinics near your location, visit our portal and avail discount on every consultation & treatment procedures.

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