Actinic Keratosis (Rough Sun-Damaged Skin): A Precancerous Condition You Should Know About

Actinic Keratosis (AK), also known as Solar Keratosis, is a rough, scaly patch or bump on the skin caused by long-term accumulated sun exposure. It is classified as a precancerous lesion and can develop into a type of skin cancer called Squamous Cell Carcinoma if left untreated. This article explains the appearance, causes, risk factors, treatment and prevention, so that you can notice skin changes early and see a dermatologist in time.

What Is Actinic Keratosis?

Actinic Keratosis is a skin lesion caused by damage to the cells of the upper skin layer (keratinocytes) from ultraviolet (UV) radiation in sunlight, accumulated over a lifetime. It is therefore common in areas that are regularly exposed to the sun. Medically, AK is considered a precancerous condition because the skin cells in the area have started to become abnormal and may go on to develop into Squamous Cell Carcinoma. For this reason, early detection and treatment are very important.

Causes and Risk Factors

The main cause of Actinic Keratosis is long-term accumulated exposure to UV radiation from sunlight. Factors that increase the risk include:

• Age over 50: It is most often seen in people over 50, because of many years of accumulated sun exposure.

• Fair skin: People with fair or light skin are more sensitive to sun damage.

• Accumulated sun exposure: Working or spending time outdoors without consistent sun protection throughout life.

• Weakened immune system: People who take immunosuppressant medication, receive chemotherapy, or have been treated with PUVA have a higher risk.

• HIV infection: People living with HIV who have reduced immunity are another group with an increased risk.

Symptoms and Appearance

Actinic Keratosis is usually found in areas that are often exposed to the sun, such as the face, ears, backs of the hands and shoulders. Its main features are as follows:

• Color of the lesion: It may be red or the same color as the surrounding skin. Some lesions may look pink.

• Rough texture: The skin in the area is rough and scaly, like sandpaper, and feels gritty to the touch.

• Pain or itching: Some people may feel pain or itching when the lesion is touched.

• Size: Lesions are generally smaller than 1 centimeter.

• Common locations: Usually found on the face, ears, backs of the hands and shoulders, which are areas regularly exposed to the sun.

Why You Should Not Delay Treatment (Risk of Becoming Cancer)

Actinic Keratosis is classified as a precancerous lesion, meaning the skin cells in the area have started to become abnormal and may develop into Squamous Cell Carcinoma if not treated. Some lesions may stay the same or go away on their own, but because it cannot be predicted in advance which lesion will become cancer, seeing a dermatologist for evaluation and treatment at an early stage helps reduce the risk and prevent progression.

Treatment Options

There are several ways to treat Actinic Keratosis. The doctor will choose the one that suits the number and location of the lesions, including:

• Cryotherapy (freezing with liquid nitrogen): Freezing the lesion with liquid nitrogen. It is suitable for a small number of clearly located AK lesions.

• Topical 5-fluorouracil (5-FU): A cream applied continuously for 2-4 weeks. It can treat several lesions at the same time.

• Imiquimod 5%: A cream that works by stimulating the body's innate immunity to clear the lesions.

• Ingenol mebutate: A topical medication applied for 3 consecutive days.

• Photodynamic Therapy (PDT): The use of light together with a light-sensitizing agent to destroy abnormal cells. It is suitable when there are lesions in several areas.

Prevention

Because the main cause of Actinic Keratosis is UV radiation, consistent sun protection is the key to lowering the risk.

• Use sunscreen: Apply sunscreen with an adequate SPF regularly, and reapply when spending long periods outdoors.

• Avoid strong sunlight: Wear a wide-brimmed hat, long sleeves and sunglasses to reduce direct sun exposure.

• Avoid the hours of strong sun: Try to stay out of the sun at midday when it is strongest, and seek shade when doing outdoor activities.

• Check your skin regularly: Keep an eye on skin in areas that are often exposed to the sun. If you notice an unusual rough patch that does not go away, see a doctor.

Frequently Asked Questions

Is Actinic Keratosis cancer? Actinic Keratosis is not yet cancer, but it is a precancerous lesion that can develop into a type of skin cancer called Squamous Cell Carcinoma if not treated. You should see a doctor for evaluation.

Where on the body is Actinic Keratosis usually found? It is usually found in areas regularly exposed to the sun, including the face, ears, backs of the hands and shoulders. The lesions are generally smaller than 1 centimeter, with rough, scaly skin like sandpaper.

How is Actinic Keratosis treated? There are several methods, such as freezing with liquid nitrogen (Cryotherapy), topical 5-FU, Imiquimod 5%, Ingenol mebutate and Photodynamic Therapy (PDT). The doctor will choose the one that suits the number and location of the lesions.

How can Actinic Keratosis be prevented? It can be prevented by avoiding sun exposure, using sunscreen regularly, wearing a wide-brimmed hat and long sleeves, and checking the skin in sun-exposed areas regularly. If you notice any unusual patch, see a doctor.

If you notice a rough, scaly patch of skin that does not go away in an area often exposed to the sun, or have concerns about your risk of skin cancer, you can consult a dermatologist at Siam Dermatology. Call +66 61 448 7000 or LINE @siamderm

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed July 16, 2026