Cryotherapy

Indications

• Actinic keratosis (first-line for isolated hyperkeratotic lesions).
• Small superficial BCC (alternative to topical / surgical for low-risk lesions).
• Small Bowen's disease lesions in well-vascularised sites (avoid lower leg).
• Viral warts, seborrhoeic keratoses, molluscum, dermatofibroma — non-oncological.
• Palliative for inoperable cutaneous metastases.

Not appropriate for invasive cSCC, melanoma, recurrent BCC, morphoeic / infiltrative BCC, or any lesion where histology has not been established.

Technique

Spray (open-spray)

1. Hold cryogun perpendicular ~1 cm above lesion.
2. Spray to produce ice ball extending 1–2 mm beyond clinical lesion margin.
3. For AK: single freeze 5–10 seconds.
4. For superficial BCC / Bowen's: double freeze-thaw cycle, 10–30 seconds each (depending on lesion).
5. Allow complete thaw between cycles.

Contact probe

Used for delicate sites (eyelid). Less aggressive but more controlled.

Aftercare

• Counsel patient: blister within hours, crust within 1–2 days, healing 2–6 weeks.
• Mild analgesia if needed; cool compress.
• Keep dry; no specific dressing required.
• Sun protection of treated site to minimise hypopigmentation.

Side effects & cautions

• Pain during and shortly after treatment.
• Blistering, crusting, occasional infection.
• Hypopigmentation — frequent and persistent in Fitzpatrick III–VI; warn explicitly.
• Hyperpigmentation in some skin types.
• Scarring (usually minimal but unpredictable).
• Atrophy and telangiectasia at treatment site.
• Cold urticaria, cryoglobulinaemia, Raynaud's — relative contraindications.
• Avoid lower-leg lesions in elderly patients with poor wound healing.
• Risk of nerve injury at sites where cutaneous nerves are superficial (e.g. lateral knee — peroneal).