What Is Actinic Keratosis?

Actinic keratosis (AK) — also called solar keratosis — is a rough, scaly patch on the skin caused by years of sun exposure. It is the most common precancerous skin condition, affecting an estimated 58 million Americans.

AKs develop when UV radiation from the sun damages the DNA in squamous cells, causing them to grow abnormally. They are not cancer, but they are considered precancerous because a percentage of untreated AKs will eventually progress to squamous cell carcinoma (SCC). For patients with multiple AKs or high-risk features, treatment is standard of care.

Symptoms

Actinic keratoses most often appear on areas of the body that receive the most sun exposure: the face, scalp (particularly in men with thinning hair), ears, back of the hands, forearms, neck, and lips.

Characteristics include:

Rough, dry, or scaly patch: Usually less than 1 inch in diameter
Flat to slightly raised surface: On a base of sun-damaged skin
Color variations: Pink, red, or brown; sometimes the same color as surrounding skin
Itching, burning, or tenderness: The area may feel irritated even without visible change
Hard, wart-like surface: In some AKs
Lip involvement (actinic cheilitis): Dryness, scaling, or a whitish discoloration of the lower lip

Multiple AKs in the same area of skin — a condition called field cancerization — indicate widespread UV damage and a higher risk of SCC development.

Causes & Risk Factors

AKs are caused by cumulative UV exposure. Almost all risk factors relate to the amount and duration of UV radiation received over a lifetime:

Chronic sun exposure: Outdoor occupations, recreational sun exposure, living in a sunny climate
Fair skin, light eyes, or light or red hair
Age over 40: AKs become more common with age as cumulative UV damage accumulates
Geographic location: High UV regions — particularly Florida, the Southwest, and high-altitude areas — have significantly higher AK prevalence
History of sunburns
Tanning bed use
Weakened immune system: Immunosuppressed patients develop AKs more readily and at higher risk of progression to SCC
Male sex: Men develop AKs more frequently, likely due to higher occupational and recreational sun exposure and less frequent sunscreen use

Diagnosis

Most actinic keratoses are diagnosed clinically — a trained dermatologist can identify them on examination, aided by dermoscopy. If a lesion looks suspicious for progression to SCC (thickened, raised, bleeding, or rapidly growing), a biopsy may be performed.

A skin biopsy is the only way to definitively determine whether an AK has progressed to SCC. Any lesion that changes significantly or doesn't respond to typical AK treatments should be biopsied.

Treatment Options

Treatment is recommended for most AKs because it is not reliably possible to predict which individual AK will progress to SCC. Options include:

Cryotherapy: Liquid nitrogen is applied to freeze and destroy the abnormal cells. The most common treatment for individual AKs. A brief, sharp discomfort followed by healing over 1–2 weeks.
Topical treatments (field therapy): For patients with multiple AKs or field cancerization
- 5-fluorouracil (5-FU) cream: Applied daily for 2–4 weeks; causes a significant inflammatory reaction that clears abnormal cells
- Imiquimod cream: Stimulates the immune system to destroy abnormal cells; applied 2–3 times per week for several weeks
- Diclofenac gel: A milder option with fewer side effects; applied twice daily for 60–90 days
- Tirbanibulin (Klisyri): A newer topical applied once daily for 5 days
Photodynamic therapy (PDT): A photosensitizing agent is applied to the skin, then activated by a specific wavelength of light. Effective for field treatment; can treat large areas at once.
Chemical peels / laser resurfacing: For extensive facial AKs
Curettage: Physical scraping for thicker, hyperkeratotic AKs

Prevention

Prevention of new AKs comes down to sun protection:

Broad-spectrum SPF 30+ sunscreen daily, even on overcast days
Reapply every two hours when outdoors
Protective clothing: Wide-brimmed hats, long sleeves, UV-filtering sunglasses
Avoid peak UV exposure between 10 AM and 4 PM
No tanning beds
Annual full-body skin exams: Allows early identification and treatment before progression to SCC

When to See a Doctor

If you notice a rough, scaly, or persistent patch on sun-exposed skin — especially if it itches, bleeds, or has been present for more than a month — have it evaluated. AKs are common and very treatable, but they are also the most direct warning sign that sun damage has reached a clinically significant level.

Patients with a history of AKs should be seen at least annually, and more frequently if they are immunosuppressed or have had multiple or recurrent lesions. Treating AKs is one of the most effective forms of skin cancer prevention available.

References

Siegel JA, Korgavkar K, Weinstock MA. Current perspective on actinic keratosis: a review. British Journal of Dermatology. 2017;177(2):350–358. doi:10.1111/bjd.14852
American Academy of Dermatology Association. Actinic keratosis: Overview. aad.org
Stockfleth E. The paradigm shift in treating actinic keratosis: a comprehensive strategy. Journal of Drugs in Dermatology. 2012;11(12):1462–1467.
Criscione VD, Weinstock MA, Naylor MF, et al. Actinic keratoses: Natural history and risk of malignant transformation in the Veterans Affairs Topical Tretinoin Chemoprevention Trial. Cancer. 2009;115(11):2523–2530. doi:10.1002/cncr.24284
Morton CA, Szeimies RM, Basset-Seguin N, et al. European Dermatology Forum guidelines on topical photodynamic therapy 2019 part 1: treatment delivery and established indications — actinic keratoses, Bowen's disease and basal cell carcinomas. Journal of the European Academy of Dermatology and Venereology. 2019;33(12):2225–2238. doi:10.1111/jdv.15defined
Lebwohl M. Actinic keratosis: epidemiology and progression to squamous cell carcinoma. British Journal of Dermatology. 2003;149 Suppl 66:31–33. doi:10.1046/j.0366-077x.2003.05621.x
Werner RN, Stockfleth E, Connolly SM, et al. Evidence- and consensus-based (S3) Guidelines for the Treatment of Actinic Keratosis. Journal of the European Academy of Dermatology and Venereology. 2015;29(11):2069–2079. doi:10.1111/jdv.13180