Actinic Keratoses (Solar Keratoses)

What causes solar keratosis to develop?

Solar keratoses are caused by damage to surface skin cells from ultraviolet sunlight. They are especially common in fair-skinned people that have lived abroad, worked outdoors, or in those that enjoy sunbathing. Ultraviolet light damages the outer layer of the skin causing cells to overgrow and this produces the raised firm scaly lesions that are seen in solar keratosis. This damage accumulates over many years of exposure and more than 20% adults aged over 60 years develop solar keratosis. Ultraviolet light is also responsible for producing premature ageing, wrinkles, flat brown pigmented skin lesions (“sun spots”), thinning of the skin (solar elastosis), and skin cancers.

Are solar keratosis harmful?

Generally speaking, solar keratosis are not harmful and can be left untreated if they are not causing any symptoms. However, patients should be aware that they are at an increased risk of developing co-existent skin cancer because they also develop in sun-damaged skin. The risk of an individual solar keratosis turning into a skin cancer is very small (less than 1 in 400 lesions each year).

Is treatment necessary?

Very early solar keratosis do not need treatment and may resolve spontaneously with sun protection. However, treatment may be warranted if they itch, bleed, become very scaly/crusty or if there is any concern about the development of a skin cancer. Sun avoidance is necessary to help reduce the number of new lesions developing.

What treatments are effective?

Persistent solar keratosis may require treatment. There are several effective treatment options and some common ones are:

Solaraze Gel® (Diclofenac and Hyaluronidase):  This is applied once daily for up to 12 weeks. It works by causing inflammation in the unstable skin cells. Treated skin lesions look worse before they improve. They may become red, sore and weep, but most patient have very minimal side effects and Solaraze is generally well tolerated. Solaraze® is about 50%-70% effective and works best in early superficial lesions. Treatment courses may be repeated.

Efudix Cream® (5-Flourauracil Cream):  Efudix® is applied twice daily for 3 weeks or once daily for 6 weeks to a small area of affected skin (typically less than 8-10 cm2 ). It works by destroying abnormal skin cells and causes a pronounced inflammation in skin lesions. It is normal to see redness, crusting, and rarely ulceration. All patients should see this skin reaction; it is part of the treatment. Treatment may need to be stopped for a few days if the reaction is very intense. You may need to ask your doctor to prescribe a topical steroid/antibiotic (Fucibet® cream) if the reaction is severe. It is 85% effective and is very effective for multiple unstable lesions. Treatment courses can be repeated or rotated around different areas.

Cryotherapy Freezing (Liquid Nitrogen):  Cryotherapy destroys the unstable skin cells allowing healthy skin cells to heal the treated area. Freezing typically takes a few seconds and wounds heal in 7-15 days. It is relatively painful but very effective (90% of skin lesions will resolve with a single freeze). Side-effects include blistering, crusting and occasionally a white permanent scar.

Photodynamic Therapy (Metvix PDT®):  Extensive facial or scalp solar keratosis may require treatment with a special cream and red light. The cream is selectively absorbed by abnormal skin cells to make a photosensitive chemical that is then destroyed by red light. It can be used for extensive disease and has the advantage that healing only takes 7-10 days with good cosmesis. Multiple treatments may be required, and each session is typically 70-75% effective.

Skin Curettage & Cautery:  Thickened or persistent solar keratosis may be better treated and removed by scraping (curettage and cautery). A local anaesthetic injection is required prior to treatment. Usually, the sample would be sent for histological analysis (biopsy). Healing typically takes 10-21 days but may be longer on the lower leg. The skin will heal with a small pink/white scar.

Do I need to be seen regularly by my dermatologist?

You don’t necessarily need to have a regular review for actinic keratoses. However for patients with many lesions, especially if they have had a skin cancer previously we would recommend you come to see one of our Consultant Dermatologists once or twice a year for a general skin review; unfortunately due to current constrains routine skin checks are not offered in NHS Dermatology clinics

Can I do anything to help the skin problem?

Studies have shown that avoidance of further exposure to sunlight reduces the number of new skin lesions. It is advisable to avoid sun exposure by covering up with light clothing, use of a wide-brimmed hat, and by wearing a high Sun Protection Factor (SPF>25) sunscreen. Try and avoid sun exposure between 11am and 3pm.