Cryotherapy in Dermatology

Advantages

• Simple, quick, repeatable, and cost-effective
• Usually no anesthesia or sutures required
• Minimal bleeding and infection risk
• Good cosmetic outcome when properly performed
• Useful in pregnancy, elderly patients, patients on anticoagulants, and those with pacemakers where electrocautery is unsuitable

Cryogens

Mechanism of Cryoablation

1. Direct cellular injury
   • Rapid freezing causes extracellular and intracellular ice-crystal formation.
   • Mechanical disruption of cell membranes and organelles occurs.
   • Extracellular solute concentration creates an osmotic gradient, causing cellular dehydration and damage.
2. Vascular injury
   • Cold induces vasoconstriction, endothelial damage, platelet aggregation, and microthrombi.
   • This produces vascular stasis, ischemia, and tissue necrosis.
3. Inflammatory injury
   • Inflammation following cell death adds to tissue destruction.

Techniques of Application

1. Timed spot-freeze technique

• Liquid nitrogen is sprayed directly through a suitable nozzle held about 1 cm from the lesion.
• Spray is continued until an ice ball forms and desired margin is achieved.
• Freeze margin:
  • Benign lesions: at least 2 mm
  • Malignant lesions: 5 mm or more
• A freeze-thaw cycle is complete after the white frozen area fully thaws.

• Open-spray technique: for large, superficial, irregular lesions or curved surfaces.
  • Paint-brush method
  • Spiral method
• Confined-spray technique: uses neoprene/polystyrene cones; useful for small discrete lesions or lesions near vital structures.

2. Cryoprobe method

• A probe is placed directly over the lesion and cooled.
• Produces a uniform and relatively deeper freeze.
• Particularly useful for vascular lesions.
• Do not pull the probe off prematurely. Allow spontaneous release during thawing.

3. Dipstick method

• A cotton bud dipped in liquid nitrogen slush or dry ice is firmly applied to the lesion until an ice halo appears.
• Cheap and convenient for small benign lesions.
• Not preferred for malignant lesions due to inadequate depth control.

4. Histofreezer

• Dimethyl ether-propane system, mainly used for warts.
• Less effective than liquid nitrogen but easy to store and use.

5. Intralesional cryotherapy

• A needle is passed through a deep lesion and cryogen is passed through it, creating an intralesional ice cylinder.
• Useful for large, deep dermal lesions, especially keloids.

Important Indications

Benign lesions

• Viral warts, including plantar and genital warts
• Molluscum contagiosum
• Skin tags
• Seborrhoeic keratosis
• Milia, xanthelasma, dermatofibroma
• Angiomas, spider nevus, venous lake, pyogenic granuloma
• Keloids, especially with intralesional corticosteroids

Other dermatoses

• Acne cysts and selected acne scars
• Hypertrophic lichen planus, prurigo nodularis, lichen simplex chronicus
• Cutaneous leishmaniasis and chromoblastomycosis
• Selected pigmented lesions such as solar lentigines and freckles, with caution

Premalignant and malignant lesions

• Actinic keratosis and actinic cheilitis
• Bowen disease
• Small, well-defined superficial BCC and superficial SCC, especially on trunk
• Cryotherapy may be palliative for cutaneous melanoma metastases

Contraindications

Absolute

• Cold intolerance
• Cold urticaria
• Raynaud disease
• Cryoglobulinemia
• Blood dyscrasias of unknown cause
• Lesions requiring histopathology
• Lesions in areas with compromised circulation
• Recurrent or sclerosing BCC, and SCC in high-risk sites such as temple/nasolabial fold

Relative

• Keloidal tendency
• Collagen vascular disease
• Dark skin, due to cosmetically unacceptable hypopigmentation
• Sensory loss at treatment site
• Pyoderma gangrenosum
• Lesions near eyelid margins, ala nasi, nasolabial fold, or hair-bearing areas
• Sites over superficial nerves or cartilage
• Poor peripheral circulation, especially digits and lower limbs

Complications

Acute

• Pain, tingling, numbness
• Edema, especially on eyelids, lips, genitalia
• Cryoblister formation
• Vasovagal syncope
• Headache after head and neck treatment

Subacute

• Hemorrhagic necrosis
• Wound infection
• Delayed wound healing, particularly on extremities
• Temporary scar hypertrophy
• Subcutaneous emphysema if sprayed over broken skin

Late/protracted

• Hypopigmentation - common, especially in dark skin
• Atrophic scar
• Hypoesthesia or nerve damage
• Milia
• Cicatricial alopecia
• Cartilage damage
• Nail dystrophy or tissue distortion in inappropriate sites
• Recurrence or incomplete clearance

Post-procedure Care

• Explain expected erythema and edema soon after treatment.
• Blister may appear after 1-3 days, followed by crusting for up to 2 weeks.
• Large blisters may be aspirated with a sterile needle, while retaining the blister roof.
• Area should be gently washed with soap and water, patted dry, and usually left open.
• Analgesics may be given for pain.
• Counsel regarding possible pigmentary alteration, scar, and need for repeat treatment.

Exam Conclusion