Cryotherapy

Essentials

• Cryotherapy is an effective and relatively safe method for the treatment of several types of skin lesions.
• Actinic keratoses and benign skin lesions can also be treated in primary health care by a physician with appropriate training.
• For successful treatment of a patient's first actinic keratoses, in particular, it is important to assess the lesions carefully (and in primary health care, not to hesitate taking biopsies).

General remarks

• It is important to make the correct diagnosis and to have experience of cryotherapy. If the diagnosis is uncertain, a biopsy specimen should be taken (histological confirmation).
• Skin biopsy is usually indicated in the following cases, at least:
  • uncertain clinical diagnosis
  • a lesion that has grown or a new lesion that has developed rapidly
  • a pigmented lesion
  • an ulcerated lesion
  • a lesion in the head area (lips or ears, in particular)
  • recurrence of a lesion after cryotherapy.
• In cryotherapy, liquid nitrogen (-196 °C) is applied to cause rapid freezing and slow thawing of the skin, leading to local tissue destruction. Repeated freeze-thaw cycles produce the most tissue destruction.
  • In the freeze stage, ice crystals form in the extracellular fluid before forming in the intracellular fluid. This increases the osmotic pressure in the extracellular fluid, thus leading to dehydration and shrinkage of the cell.
  • Intracellular ice crystals disrupt the cellular structures. During thawing, fluid quickly returns to the cells, which swell up and rupture.
  • Damage to the capillary endothelium in the skin leads to thrombosis and ischaemic necrosis.
  • Badly damaged cells undergo apoptosis.
• Required equipment
  • A liquid nitrogen tank and transfer line for filling the flask
  • A metal thermos flask (cryotherapy flask) with valves and attachments for replaceable cryotherapy tips
  • A cryotherapy tip (such as a spray tip, confined spray tip or closed probe). The size of the spray tip hole (A-D) affects the speed of treatment and the spread of the freezing effect to surrounding skin.
• Advantages of cryotherapy
  • Analgesia usually unnecessary (with the exception of intense freezing treatment)
  • Quick to perform at a doctor's office
  • Cost-effective
  • Cosmetic outcome usually good (more intense freezing practically always leaves a scar and permanent hypopigmentation; in people with dark skin types, there may be residual hyperpigmentation)
  • Low risk of infection

Cryotherapy in practice Photodynamic Therapy for Actinic Keratoses, Topical Creams and Cryotherapy for Actinic Keratoses, Local Treatments for Cutaneous Warts

• The most common cryosurgical technique is the open spray technique using a type B or C tip. Targeting of the liquid nitrogen depends on the lesion treated. Various techniques are used for this.
  • The liquid nitrogen can be delivered directly to the centre of the lesion, then waiting for the freezing to extend all the way to the margins (for benign skin lesions, in particular).
  • Delivery can be started at the margins, and once these have frozen, slowly continued in a rotary pattern moving towards the centre of the lesion (rotary technique, for basal cell carcinoma, for example).
  • The tip can be moved like a paintbrush over the whole area to be treated (paintbrush method).
• The spray technique is suitable for treating both smaller and larger skin lesions. Neighbouring tissues sensitive to cryotherapy (such as the eyes, ear canals, mucosa) must be covered, as necessary.
• The contact technique can be used in specialized care for areas where freezing must be accurately limited (such as around the eyes).
• In the forceps method, the tip of a metal forceps is immersed in liquid nitrogen and the forceps is then immediately used to grasp the skin lesion to be frozen (suitable for benign lesions growing out of the skin, such as protruding warts with thin stalks, or skin tags).
• How quickly the skin area freezes and thaws depends on the thickness of the area and the circulation there, and the required freezing time depends on this.
• The lesion area should be anaesthetized and curetted carefully, as necessary. Any bleeding can be stopped by using an aluminium or ferric chloride solution (a swab moistened with the solution).
• Don't forget to protect the patient's eyes, nostrils and ear canals when using cryotherapy.
• The intensity of freezing is normally assessed visually (benign skin lesions).
• The intensity of freezing of malignant lesions can be assessed by the time taken for the margin of the frozen area to thaw.
  • When the margin of the frozen area extends beyond the margin of the skin lesion, you can assess how long it takes for the white frozen margin to thaw back to the margin of the skin lesion (halo thaw time, HTT).

Cryotherapy of benign lesions

• Highly suitable lesions: warts , condylomas , molluscs , seborrhoeic keratosis , skin tags
• Other lesions: benign pigmented lesions, such as melasma and freckles (N.B., experience and certain diagnosis!); sebaceous hyperplasia, myxoid cyst , keloids or hypertrophic scars Keloid and Hypertrophic Scar (usually combined with glucocorticoid injections); pyogenic granuloma (can first be confirmed histologically and cryotherapy applied only after receiving the results); venous lake of the lip or mucocele of the lip (usually with the contact technique); eccrine chalazion i.e. hidrocystoma (usually with the contact technique)
• Freeze until the freeze margin extends to the lesion margin or slightly beyond it, and then stop. The lesions will be shed or become smaller in 2-3 weeks without further measures. Lesions normally need to be frozen once or twice (Table T1).
• For cryotherapy of seborrhoeic keratosis, see series of images , video Cryotherapy of Seborrhoeic Keratosis.

Cryotherapy of actinic keratosis

• See picture , series of images and videos Curettage and Cryotherapy of Actinic Keratosis Cryotherapy of Actinic Keratosis.
• Curette any thick hyperkeratoses superficially, as necessary. If there is clearly thickened skin or raw ulceration underneath the hyperkeratosis, a biopsy sample should be taken.
• The lesion should be completely frozen and allowed to stay frozen for a while, normally 5-20 seconds, depending on the skin area (for the face, 5-10 seconds is usually enough).
  • 2-3-mm margin (of frozen area beyond the skin lesion)
  • Usually 2 freeze-thaw cycles per session
• Actinic keratoses can also be treated in primary health care by a physician with appropriate training. Particularly when treating a patient's first actinic keratoses, the diagnosis should be confirmed histologically (biopsy).
• Checkup after 3-6 months

Intense freezing (basal cell carcinoma or carcinoma in situ)

• Can be used by a medical specialist or a physician with special expertise in cryotherapy, as necessary.
• Must never be used below knee level, as this can easily lead to chronic ulceration in that area. Should be used for fingers only after careful consideration. Should basically not be used in primary health care for lesions in the head or neck area at all.
• When treating lesions in the head area in specialized care, the cosmetic and functional results and risk of recurrence should be carefully considered.
• Checkup after 3-6 months

Contraindications

• The contraindications presented here are only relative. Any advantages or disadvantages of treatment must be considered case by case, considering also the physician's experience in cryotherapy.
  • Skin lesion below knee level or at a bony protuberance (risk of chronic ulcer)
  • Particularly in the case of malignant or premalignant skin lesions: a large (over 2 cm) or thick (over 3 mm) lesion or a lesion with indistinct margins (risk of chronic ulcer or recurrence)
  • Uncertainty of exact diagnosis of the lesion
  • Patients with cold urticaria, cryofibrinogenaemia, cryoglobulinaemia, Raynaud's phenomenon, multiple myeloma
  • Severe immunodeficiency (such as agammaglobulinaemia), autoimmune bullous diseases, pyoderma gangraenosum

Aftercare

• Freezing causes a degree of tissue damage depending on the intensity of freezing. The patient should be given written instructions for aftercare and an explanation of what is to be expected after the treatment.
• Less intense freezing (of benign lesions and actinic keratoses) usually requires no aftercare. Washing, swimming, sauna bathing and wearing makeup can be allowed. Healing usually takes 2-3 weeks.
• After intense freezing, oedema appears nearly immediately and clinical necrosis in 1-7 days. Oozing of tissue fluid begins on the day after freezing. Pain developing during healing in a normally painless treated area suggests a bacterial infection.
• For aftercare, the area should be washed with water at least once daily. After treatment, the area can be covered with a paraffin dressing and compresses.
• In addition, an antimicrobial ointment (fusidic acid, for example) can be applied once or twice daily after washing for 1-2 weeks, as necessary. Healing may take 4-6 weeks.

Adverse effects and complications

• There is usually only mild pain; local anaesthesia is usually necessary only if using the basal cell carcinoma technique.
• Intense freezing causes a fluid-filled blister and swelling in the skin area. In some cases, healing of the ulcer may be prolonged. Secondary infections are possible but rare (suppuration in the area, extensive erythema, pain, general symptoms).
• Hypopigmentation (particularly in patients who have dark skin or who tan easily); hypopigmentation may also occur after the treatment of benign lesions. Patients with dark skin may develop reactive hyperpigmentation.
• After intense freezing, an erythematous scar ridge or circle may develop in a few months. Any scar will usually become lighter and fade away almost completely in less than a year.
• Intense freezing close to the vermilion border or nostrils or of the eyelid may cause tissue retraction.
• Intense freezing of a hairy area will destroy the hair follicles; after mild freezing, hair growth rarely stops.
• Rarer complications include hypertrophic scars and keloids.

Pictures