Actinic Keratosis, also known as solar keratosis, actinic keratosis is a very common pre-cancerous lesion that is induced by UV light. Fortunately, early treatment can eliminate almost all actinic keratoses before they become skin cancers. Written by Dr Ian Webster
Actinic keratosis (AK) or solar keratosis is an extremely common UV light-induced precancerous lesion of the skin that may progress to an invasive squamous cell carcinoma (SCC). In the USA, it is the second most frequent reason for a patient to consult a dermatologist.
It usually occurs on sun-exposed areas in people with a fair skin who’ve had long term sun exposure. Australia has one of the highest prevalence of AKs, with up to 60% of Australians over the age of 40 being positively diagnosed. The actual percentage of AKs that will progress to an invasive SCC is unknown. Estimates have varied from as low as 0.1% to as high as 10%. A small percentage may regress spontaneously.
They usually present as single or multiple red, scaly papules that are often felt – rather than being seen – on sun-exposed areas. Most AKs are between 3 mm to 10 mm in diameter. There are various clinical subtypes including pigmented, atrophic, bowenoid, lichen planus-like or hyperkeratotic.
And while the diagnosis is mainly a clinical one, it may be necessary to perform curettage and cautery – and send the specimen for histology to ascertain whether the lesion is in fact an AK or SCC (especially in the hyperkeratotic or cutaneous horn-like AKs). However, as we cannot predict which individual AK could become a squamous cell carcinoma, it is generally recommended that all visible AKs receive treatment.
All patients should be counselled about photoprotection, in other words, sun avoidance, sun protection and the regular use of a high factor, broad spectrum sunscreen.
A number of clinical trials have demonstrated that the regular use of a high factor, broad spectrum sunscreen does in fact reduce the number of AKs, as well as reducing the incidence of SCC.
It is generally recommended to use liquid nitrogen (boiling point -196°C) either in the form of a cryo-spray or using a cottonwool bud soaked in liquid nitrogen.
I prefer using the cryo-spray method, especially on the thicker AKs on the scalp and body, while using the cottonwool bud method on the face (especially around the eyes). Cryotherapy is the recommended first line treatment of choice, particularly for single AKs, or if there are less than six AKs in one body region or field.
The advantage of the cryotherapy is that it is readily available, inexpensive and can be performed immediately, usually at the initial consultation. The AKs that have been frozen with the liquid nitrogen usually heal quickly, within 7 to 10 days. A potential side-effect of cryotherapy however, is post-inflammatory hypopigmentation.
Curettage and cautery
This is mainly useful in a single, larger hyperkeratotic AK where other treatment modalities would not be as effective.
In this instance, an AK is removed under local anaesthetic by using a sharp, spoon-like surgical instrument (called a curette) to scoop out the lesion, followed by electrocautery for haemostasis (to stop the bleeding).
The curetted specimen should obviously be sent for histology to exclude an invasive SCC.
A topical cytotoxic agent is useful where there is field cancerisation, i.e. where there are more than six actinic keratosis in one body region or field. The ointment is generally applied twice a day for two-three weeks.
The affected area will become red and scaly and may be uncomfortable. Therefore, the downtime for this treatment would be three-four weeks. Fortunately, 96% of patients with 5-FU will achieve initial clinical clearance.
As with the above, this agent is also indicated where there is field cancerisation i.e. more than six AKs in more than one body region or field. For AKs it is recommended that cream be applied overnight, three times a week for four weeks.
So the patient’s downtime would be in the region of five weeks. The cream works by stimulating your own immune system to kill off the AKs, i.e. it works from the inside out. The big advantage of this agent is that there is an excellent initial clinical clearance rate, with a low recurrence rate at 12-month follow-up. There is also generally a good cosmetic outcome.
Photodynamic treatment (PDT)
An ideal treatment therapy for when there is a field cancerisation, i.e. more than six AKs in one body region or field. A photosensitising chemical is applied to the skin, followed by a light source to activate the drug.
It may be quite painful and is often given under conscious sedation. However, while this treatment may uncomfortable and a bit more expensive, the big advantage is that there is less downtime (approximately 7 to 10 days).
AKs are an extremely common condition seen in dermatology practices, but we fortunately have a number of excellent modalities of treatment available to effectively treat them and prevent progression to SCC.
Reference: Evidence & consensus based guidelines for the treatment of actinic keratoses JEADV 2015 : 20168-2079
For more information on Actinic Keratosis and to learn how to protect your skin from the sun and detect problems early, visit www.beskinsmart.co.za
A2 Disclaimer: This article is published for information purposes only, and should therefore not be taken as an endorsement – nor should it be regarded as a replacement for sound medical advice.
This article was written by Dr Ian Webster and edited by the A2 team EXCLUSIVELY for the A2 Aesthetic & Anti-Ageing Magazine June 2018 Edition (Issue 26).
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