Non-surgical physical therapy
- Know the indications for and describe the use of physical therapies in the treatment of skin lesions.
- Cryotherapy is used to remove superficial skin lesions.
- The boiling point of liquid nitrogen is –196C.
- A temperature of –30 to -50C ensures destruction of malignant cells.
- Cryotherapy may cause blistering, haemorrhage and ulceration.
- Loss of hair and sweating, hypopigmentation and scarring may be permanent.
- Current indications for radiotherapy of skin disease include some basal cell and squamous cell cancers, lymphomas and rarely, intractable localised inflammatory skin disease.
- Photodynamic therapy (PDT) involves an oxygen-dependent phototoxic reaction and is used to treat superficial forms of non-melanoma skin cancer.
- Laser light is monochromatic, collimated and coherent.
- Pulsed laser light reduces transmission of heat to surrounding tissues.
- The wavelength of laser light used depends on the absorption spectrum of the skin lesion.
- Yellow light is often used to remove vascular skin lesions.
- Carbon dioxide and erbium lasers can be used for facial resurfacing and to vaporise epidermal lesions.
- Lasers and flash lamps producing various wavelengths are available for hair removal and permanent reduction of dark hairs.
Physical therapy of skin diseases refers to treatment that employs heat, cold, ionising and non-ionising radiation
Cryotherapy is used to reduce or remove superficial skin lesions, including:
- Solar keratoses
- Seborrhoeic keratoses
- Benign lentigines
- Viral warts
- Using a special technique, superficial non-melanoma skin cancers.
It should not be used if there is any doubt about the pathology of the lesion, especially if melanoma is within the differential diagnosis.
Liquid nitrogen (boiling point –196C) is the most useful cryogens and can be applied to the lesion using a loose cotton-tip swab or a hand-held spray unit, which provide a constant fine jet of liquid nitrogen.
Tissue injury depends on the rate of cooling, minimal temperature reached and freeze/thaw time. A temperature of –30 to -50C ensures destruction of malignant cells, particularly if the freeze/thaw cycle is repeated.
Benign superficial skin lesions may resolve with freeze/thaw times of about 20 seconds but effective cryotherapy of malignant lesions requires training and experience. Longer freezes cause deeper damage and greater morbidity.
Adverse reactions include:
- Short term blistering, exudation, haemorrhage, ulceration
- Long term adnexal damage, anaesthesia, hypopigmentation and scarring
Immediately after freezing
Erythema and swelling an hour after freezing
Haemorrhagic blister the day following cryotherapy (also clear blister on right lower lip)
Oedema and wound infection 3 days after cryotherapy
Several months after cryotherapy there is hypopigmentation and recurrence of skin cancer
Radiotherapy is the use of ionising radiation to treat skin diseases. Although frequently used in the 1960's and 70's to treat benign and malignant skin conditions, radiotherapy is rarely recommended nowadays because of the risk of the development of further malignancies and poor long term cosmetic results.
Current indications for radiotherapy of skin disease include:
- Some basal cell and squamous cell cancers in the elderly
- Some lymphomas
- Rarely, intractable localised inflammatory skin disease.
Malignant skin lesions are treated with multiple fractions of superficial X-rays delivered over two or three weeks. Treated areas become inflamed and may ulcerate before healing. Eventual scars tend to have a waxy atrophic appearance with telangiectasia and a tendency to break down with minor injury.
Photodynamic therapy (PDT) involves an oxygen-dependent phototoxic reaction and is used to treat superficial forms of non-melanoma skin cancer. The photosensitiser (usually a porphyrin) can be given intravenously or can be applied to the target lesion topically. It is selectively localized in the target tissue and is later illuminated with visible light, resulting in photodamage and subsequent cell death.
There is minimal damage to surrounding normal tissue hence side effects are limited to the target area. As a rule, cosmetic results are good or excellent.
The day following PDT
One month following PDT
Lasers were first used in New Zealand in the 1980's to treat vascular birthmarks (port wine stains). The word 'laser' is an acronym for 'Light Amplification by Stimulated Emission of Radiation'. Current therapeutic lasers remain expensive and hence are restricted to a small number of dermatology and appearance medicine practices in major centres.
The important properties of laser light are:
- Monochromatic (single wavelength)
- Collimated (parallel beam)
- Coherent (in phase)
- Continuous wave or pulsed (to reduce transmission of heat to surrounding tissues)
Different models are now commonly used to treat the following type of skin lesion:
- Red lesions: yellow light to remove facial telangiectasia and vascular birthmarks;
- Brown lesions: green or red light to remove freckles and pigmentation;
- Tattoos: various wavelengths are required to remove different colours;
- Epidermal lesions (skin tags, viral warts, seborrhoeic keratoses): a bloodless knife;
- Facial resurfacing; vaporisation by carbon dioxide or erbium lasers;
- Scar revision;
- Epilation: hair removal and permanent reduction of dark hairs using various wavelengths.
After copper bromide vascular laser treatment
Advantages of laser treatment include:
- More precise hence less risk of damage to other tissues or scarring;
- For some indications, it is more effective than other known treatments;
- It may be quicker or more convenient than other treatments.
Microwaves and non-coherent broadband flash lamps are also available for hair removal. A flash lamp may also be useful to treat vascular lesions and for non-ablative rejuvenation of the skin.