Solar keratosis

Summary

• Solar keratosis is a pre-cancerous growth caused by long-term sun exposure. It's common in fair-skinned people living in sunny climates such as South Africa and Australia.
• Solar keratoses range from barely perceptible rough spots a few millimetres in diameter, to harder patches several centimetres in diameter. They may be flaky or scaly, may peel, and don't heal properly.
• Your doctor will base the diagnosis of solar keratosis on the appearance of the skin growths.
• A solar keratosis is usually removed by freezing it with liquid nitrogen. Other treatment options include cautery, curettage, application of medicated cream or laser therapy.
• The condition can be effectively treated and the prognosis is usually good, if detected early. If left untreated, however, there is a risk that it can progress to become squamous cell carcinoma, a type of invasive skin cancer.
• he most important preventative step is to avoid sun exposure.

Alternative names

Actinic keratosis

Definition

Solar keratosis is a growth on the skin that may lead to an invasive form of skin cancer and which is caused by long-term sun exposure. Solar keratoses are skin lesions that may be flat or thickened, warty or scaly, the same colour as your skin, pink or red.

Solar keratosis is common in fair-skinned people and in people who have worked outdoors for long periods of time. People living in sunny climes such as South Africa and Australia are particularly at risk.

The condition becomes more common after age 40, but also occurs in people in their 20s and 30s, especially in those who didn't practise sun protection in their youth. The risk continues to rise with age.

Causes

Solar keratosis growths occur in sun-exposed skin areas and are caused by long-term, UV-induced skin damage.

Symptoms

Solar keratoses range from barely perceptible rough spots a few millimetres in diameter to harder patches several centimetres in diameter. They may be flaky or scaly, may peel, and don't heal properly. They may be a different colour to the surrounding skin, but early keratoses are often easier felt than seen.

Sometimes a horn-like growth of hard skin appears to come out of a solar keratosis (cutaneous horn).

Keratoses occur more commonly on areas of the skin that have received repeated sun exposure, such as the face, ears, bald scalp, neck, shoulders, forearms and backs of the hands.

The keratoses can be unsightly and slightly uncomfortable (for example you may experience an itchy or pricking sensation).

Diagnosis

Your doctor will base the diagnosis of solar keratosis on the appearance of the skin growths. A skin biopsy could reveal signs of cancerous changes.

Treatment

The main aim of treatment is to remove the defective skin cells. Treatment is usually advised if you have more than one keratosis. Options include:

1. Cryotherapy
Solar keratoses are usually removed by cryotherapy, that is freezing with liquid nitrogen (the nitrogen is so cold that it destroys the diseased tissue). This is a quick, inexpensive procedure. It can be a bit painful, causing a burning sensation, but this doesn't last long.

Cryotherapy may result in a small, unobtrusive blister on the treated area, which will peel off after a few days, leaving a reddened mark. After a period of about two weeks, the skin should be completely clear. However, if the keratoses are on the legs, it may take a bit longer to heal.

2. Medicated cream
If the condition is more extensive, for example if there are several growths, a medicated cream such as 5-fluorouracil cream, may be prescribed. This causes redness and discomfort as part of the treatment process, which makes the skin look worse. However, healing starts as soon as the use of the cream is discontinued, and the results are usually excellent.

Another medicated cream that produces excellent results is imiquimod (Aldara), which causes an inflammatory reaction in the skin. It also makes the skin look worse at first, but the area gradually settles down after the cream has been used for a few weeks.

3. Cautery, curettage or laser
E electrical cattery (burning) as well as curettage can also be used to treat the condition. Cattery works particularly well for thicker keratoses, and is commonly used to remove early squamous cell cancers. This process yields a scab, which heals over a couple of weeks. Curettage involves the scraping of the skin to remove the diseased tissue.

L asters and other light sources (photodynamic therapy) are alternative treatment options.

What is the prognosis?
Solar keratosis can be effectively treated and the prognosis is usually good if detected early.

If left untreated, however, the condition can progress to become squamous cell carcinoma, a type of invasive skin cancer. This is a slow-growing cancer which can usually be effectively treated. But if left for too long, it can be disfiguring and has the potential to spread to other parts of the body and even prove fatal.

If you have more than ten solar keratoses, your risk of getting squamous cell carcinoma is about 10-15 percent.

When to call your doctor

Make and appointment with your doctor if areas of persistent roughness or scariness develop in sun-exposed skin areas.

If you've already been diagnosed with the condition and a keratosis becomes thickened or ulcerated, have it checked out as it may have progressed to skin cancer. Make a point of going for regular skin check-ups as you're also at risk of developing other forms of skin cancer.

Prevention

The most important preventative step is to avoid sun exposure.

Always:

• Stay out of the sun between 9am and 3pm, especially in summer
• Wear a high factor sunscreen (SPF 30+)
• Cover up with long sleeves, a hat and good sunglasses

Also get well acquainted with every inch of your skin. Most people know the importance of keeping an eye on the heavily pigmented spots (such as moles), but you need to extend that scrutiny to all suspicious spots.

A good idea for keeping track of moles and other possible 'sun spots' is to photograph them periodically, then compare the pictures for any changes. Don't forget about those bits you don't usually see, such as your back. Get a partner or friend to check on the spots you can't easily see in the mirror.

Many studies indicate that a healthy lifestyle in general - a diet low in animal fats and high in fruits and vegetables, getting enough rest and exercise, and avoiding tobacco smoke - helps protect against cancer. This includes skin cancer.