Actinic keratosis: a precancerous lesion that requires monitoring

Health information prepared under the supervisionof Arnaud, Ph.D. in Pharmacy. Sources: Haute Autorité de Santé (HAS), Société Française de Dermatologie (SFD), Inserm, International Agency for Research on Cancer (IARC). This article is not a substitute for a dermatological consultation. If you notice any suspicious lesions, consult a dermatologist.

What is actinic keratosis?

Actinic keratosis (AK), also known as solar keratosis, is a precancerous skin lesion caused by chronic exposure to ultraviolet (UV) rays— whether natural (sunlight) or artificial (tanning beds, classified as Group 1 carcinogens by the IARC). It develops on areas of the skin chronically exposed to sunlight: the face (forehead, nose, cheekbones, temples), ears, lips (actinic cheilitis), scalp in people with alopecia, backs of the hands, forearms, and décolletage.

Actinic keratosis is part of a dermatological continuum that, if left untreated, can progress to cutaneous squamous cell carcinoma. The individual risk of transformation from a single lesion is low, but when accumulated over a large number of lesions and several years, it becomes significant. The concept of a “field of carcinogenesis” is central: the area surrounding visible lesions is also exposed and harbors subclinical cellular abnormalities.

What are the symptoms of actinic keratosis?

Actinic keratosis lesions have characteristic clinical features:

• A rough texture, similar to sandpaper, sometimes more noticeable to the touch than to the eye.
• Scaly or keratoticplaques ranging from a few millimeters to 1–2 cm.
• Pink, red, beige, brown, or skin-colored, sometimes with an erythematous base.
• Possibleitching, tingling, or local tenderness.
• Several clinical forms exist: classic (erythematous-scaly), hypertrophic, lichenoid, pigmented, and atrophic.

Warning signs requiring immediatedermatological consultation: a lesion that thickens rapidly, bleeds at the slightest trauma, ulcerates, becomes spontaneously painful, or exceeds 1 cm in size. These signs may indicate a potential transformation into squamous cell carcinoma.

How can actinic keratosis be prevented?

Prevention relies on rigorous sun protection throughout one’s life:

• Daily application of broad-spectrum sunscreen (UVA + UVB) with an SPF of at least 50 for fair skin types and high-risk areas.
• Apply a sufficient amount (approximately 2 mg/cm², or one teaspoon for the face and neck) and reapply every 2 hours during sun exposure.
• Clothing-based sun protection: wide-brimmed hats, UV-protective clothing, and CE-certified sunglasses.
• Avoid sun exposure between noon and 4 p.m., when UV radiation is at its peak in metropolitan France.
• Always seek shade during prolonged outdoor activities.
• Strictly avoid tanning beds, which are prohibited for minors in France and classified as carcinogenic by the IARC.
• Check your skin regularly (self-examination every 3 to 6 months for those at high risk) and consult a dermatologist if in doubt.

Several studies (notably the ONTRAC trial published in the New England Journal of Medicine in 2015, Chen et al.) have documented a moderate protective effect of oral nicotinamide (vitamin B3) at a dose of 500 mg twice daily in high-risk patients, with a reduction of approximately 23% in actinic keratoses. This approach should be discussed with a dermatologist before starting any long-term supplementation.

What are the treatment options for actinic keratosis?

The choice of treatment depends on the number of lesions, their location, their thickness, and the clinical context. All treatments are prescribed and administered by a dermatologist:

• Liquid nitrogen cryotherapy: the most commonly used technique for isolated lesions. Local application of liquid nitrogen that destroys abnormal cells by freezing.
• Prescription topical treatments: 5-fluorouracil (5-FU), imiquimod, ingenol mebutate (withdrawn from certain markets), and diclofenac gel. These target an entire area of skin and cause local inflammatory reactions.
• Photodynamic therapy (PDT): application of a photosensitizing agent followed by exposure to a specific light. Particularly suitable for extensive areas of precancerous changes.
• Curettage and electrocoagulation: mechanical ablation followed by cauterization, for thick or suspicious lesions.
• Ablative lasers: an alternative for targeted indications.
• Surgery: reserved for lesions suspected of being malignant, to allow for histological analysis.

No cosmetic treatment or dietary supplement can replace these medical interventions. However, dermo-cosmetic products (moisturizers, reparative balms, ceramides, after-sun treatments) may support post-treatment skin recovery, as advised by a dermatologist.

How is actinic keratosis diagnosed?

The diagnosis is made by a dermatologist based on a clinical examination, including visual inspection and palpation of the lesions, as well as a comprehensive examination of the skin. The examination may be supplemented by:

• Dermoscopy: examination under a magnifying lens with polarized light to determine the nature of the lesions.
• Skin biopsy with histopathological analysis: recommended in cases of diagnostic uncertainty, when signs of transformation are present, or in the case of a thick, ulcerated, or painful lesion.

The dermatologist also assesses the area at risk for cancer and other skin lesions (carcinomas, nevi requiring monitoring). In cases of uncertainty regarding other lesions, advanced photoaging of the skin may accompany the keratoses in the same areas.

Can actinic keratosis develop into cancer?

Yes, actinic keratosis is considered a precursor to cutaneous squamous cell carcinoma. According to available data (HAS, SFD), the risk of transformation per isolated lesion per year is low (estimates ranging from 0.025% to 16% depending on the study, most often around 1% per lesion per year), but this risk becomes significant when the lesions are numerous, long-standing, or located within an extensive field of precancerous changes.

Cutaneous squamous cell carcinoma, when detected early, generally has a good prognosis. Regular dermatological follow-up is therefore key to optimal management. Any lesion that thickens, bleeds, ulcerates, or becomes painful should be evaluated promptly.

What is the prognosis for a person with actinic keratosis?

With appropriate dermatological care and rigorous sun protection, the prognosis is favorable in the vast majority of cases. Current treatments allow for the effective eradication of lesions, and prevention of recurrence relies on:

• Strict daily sun protection.
• Regular dermatological follow-up (usually every 6 to 12 months, depending on individual risk).
• Regular self-examination of exposed areas.
• Early treatment of new lesions.

People with actinic keratoses have an increased risk of developing other skin cancers (basal cell carcinomas, melanomas); therefore, dermatological follow-up includes a complete examination of the skin.

How common is actinic keratosis in adults?

Actinic keratosis is a very common condition, the prevalence of which increases with age and latitude (high prevalence in countries with intense sunlight). In Europe, several studies (Werner 2013, Heerfordt 2017) report a prevalence of approximately 15 to 25% among adults over 60 with fair skin types, with higher rates in Australia and Mediterranean countries.

The increase in outdoor activities, summer tourism, and the historical use of tanning beds also explains its occurrence in younger adults (ages 40–50), particularly among those who experienced repeated sunburns during childhood and adolescence.

Are there genetic factors that influence actinic keratosis?

Several individual risk factors have been identified:

• Fair skin type (I and II according to the Fitzpatrick classification): skin that burns easily, tans poorly, light or red hair, light-colored eyes.
• Low levels of protectivemelanin.
• Personal or family history of skin cancer or actinic keratoses.
• Advanced age and cumulative UV exposure (“sun capital” depleted).
• Immunosuppression (organ transplant recipients, immunosuppressive treatments, certain blood disorders): significantly increased risk requiring close dermatological monitoring.
• Rare genetic disorders (xeroderma pigmentosum, Gorlin syndrome).
• Occupational sunexposure (farmers, sailors, construction workers).

Can actinic keratosis go away on its own?

Some lesions may regress spontaneously, but they tend to recur at the same site. Studies report varying rates of spontaneous regression (up to 25% at one year for certain cohorts), but an equal or greater proportion of lesions persist or reappear. Lack of treatment exposes patients to the risk of progression and transformation.

It is therefore not recommended to wait for “spontaneous resolution”: any suspicious lesion should be evaluated by a dermatologist, who will decide on treatment or simply monitoring depending on the circumstances.

How can actinic keratosis be distinguished from other skin lesions?

The differential diagnosis includes several skin lesions that may resemble actinic keratosis:

• Early-stage cutaneous squamous cell carcinoma: must be distinguished from actinic keratosis, as the treatment is different.
• Superficial basal cell carcinoma.
• Seborrheic keratosis: a common, benign lesion, frequently seen in people over 50.
• Pigmented spots and solar lentigines: flat, without scaling.
• Localized eczema, plaque psoriasis.
• Seborrheic wart.
• Discoid lupus, dermatomyositis (rarer inflammatory forms).

The dermatologist distinguishes these lesions through clinical examination, dermoscopy, and, if necessary, a biopsy. No remote self-assessment can replace this examination.

What are the psychological impacts of actinic keratosis?

Living with actinic keratosis can cause significant anxiety, related to the visible appearance of the lesions on the face and the fear that they may develop into cancer. The treatments themselves (redness, scabbing, and a burning sensation lasting 1 to 3 weeks, depending on the technique) can affect self-image and social life.

Here are some suggestions for managing these issues:

• Talk to your dermatologist about your expectations and the anticipated effects of the treatment.
• Use soothing and restorative post-treatment skincare products (ceramides, panthenol, allantoin, after-sun lotions) as recommended by your dermatologist.
• Seek psychological support if you experience significant anxiety or if the treatment is affecting your quality of life.
• Join patient groups or dermatology associations to share experiences.

Regular follow-up and strict sun protection help restore confidence in managing the condition over the long term.

This article is for informational purposes only. If you notice a suspicious skin lesion (rough, persistent, thickening, bleeding, or ulcerating), make an appointment with a dermatologist. Early detection leads to simpler treatment and a better prognosis.