Summary

Cryotherapy is a common dermatological procedure that uses extremely cold temperatures, typically liquid nitrogen (-196°C), to destroy abnormal or unwanted tissue. It works by forming intracellular ice crystals, which cause cell rupture and subsequent tissue necrosis. Cryotherapy is used to treat a wide range of benign, premalignant, and superficial malignant skin lesions including viral warts, seborrhoeic keratoses, actinic keratoses, and superficial basal cell carcinomas. The procedure is quick, relatively inexpensive, and can be performed in primary care or dermatology clinics. Common side effects include pain, blistering, and permanent hypopigmentation, the latter being particularly important in patients with darker skin.

Key Facts

• Temperature: Liquid nitrogen at -196°C
• Mechanism: Intracellular ice formation → Cell lysis → Vascular stasis
• Indications: Warts, Seborrhoeic keratoses, Actinic keratoses, Superficial BCC
• Technique: Spray or cotton bud; Freeze-thaw-freeze for more aggressive treatment
• Side Effects: Pain, Blistering, Hypopigmentation (permanent)
• Caution: Dark-skinned patients (hypopigmentation risk)

Clinical Pearls

"Double Freeze for Doubly Tough": Freeze-thaw-freeze (FTF) cycles are more effective for warts and premalignant/malignant lesions.

"White Halo = Endpoint": The appearance of a white ice ball extending 1-2mm beyond the lesion is the endpoint for each freeze cycle.

"Hypopigmentation is Permanent": Counsel all patients about skin colour changes, especially those with darker skin.

"Never Freeze Over a Nerve": Avoid cryotherapy over superficial nerves (e.g., lateral finger, temple) — risk of permanent neuropathy.

Lesions Suitable for Cryotherapy

Contraindications

Assessment

• Confirm clinical diagnosis
• Document lesion size and location
• Assess skin type (Fitzpatrick)
• Check for contraindications (cold urticaria, Raynaud's)

Informed Consent

• Explain procedure
• Discuss expected outcomes
• Side effects: Pain, blistering, hypopigmentation
• Multiple treatments may be needed (warts)

Cryotherapy Technique

┌──────────────────────────────────────────────────────────┐
│   CRYOTHERAPY PROCEDURE                                  │
├──────────────────────────────────────────────────────────┤
│                                                          │
│  EQUIPMENT:                                               │
│  • Liquid nitrogen (-196°C)                              │
│  • Spray gun (CryoAC, CryoPro) OR Cotton bud             │
│                                                          │
│  PREPARATION:                                             │
│  • Debride hyperkeratotic lesions (warts)                │
│  • Protect surrounding skin (Vaseline)                   │
│                                                          │
│  TECHNIQUE:                                               │
│  • Apply liquid nitrogen to lesion                       │
│  • Aim for white ice ball 1-2mm beyond edge              │
│  • Hold for appropriate freeze time (5-30s depending)    │
│  • Allow complete thaw                                   │
│  • Repeat for FTF cycle if indicated                     │
│                                                          │
│  FREEZE TIMES (Guidelines):                               │
│  • Benign (warts, SK): 5-10 seconds                      │
│  • Premalignant (AK): 10-20 seconds x 2 cycles           │
│  • Superficial BCC: 30 seconds x 2 cycles + 3mm margin   │
│                                                          │
│  POST-PROCEDURE:                                          │
│  • Advise about blistering (normal)                      │
│  • Keep clean, do not pop blister                        │
│  • Review in 2-4 weeks (or earlier if concern)           │
│                                                          │
└──────────────────────────────────────────────────────────┘

Warts

• Clearance rate 70-80% (may need multiple treatments)

Premalignant Lesions

• High cure rates for AK (>90%)

Superficial BCC

• Cure rate ~90-95% (but histological clearance not confirmed — use with caution)

Key Guidelines

1. BAD: Guidance on the Use of Cryotherapy

Key Evidence

Actinic Keratosis

• Cryotherapy effective first-line treatment

Warts

• Evidence supports cryotherapy but multiple treatments often needed

What is Cryotherapy?

Cryotherapy uses very cold liquid nitrogen to freeze and destroy skin lesions like warts, age spots, and sun-damaged skin.

What Happens During the Procedure?

• Liquid nitrogen is sprayed or applied to the lesion
• The treated area turns white during freezing
• You'll feel a cold, stinging sensation

What Happens After?

• The area may blister — this is normal
• The blister will dry out and the lesion will fall off over 1-3 weeks
• A small scar or lighter area of skin may remain

Is It Safe?

Yes, cryotherapy is very safe when done correctly. However:

• It can cause permanent lightening of the skin (especially in darker skin)
• Multiple treatments may be needed for warts

Does It Hurt?

There is some pain during and after the procedure — like an ice burn. Paracetamol can help.