Actinic keratosis !
An actinic keratosis is a rough, scaly spot on sun-damaged skin. It is a precancerous lesion that can turn into skin cancer.
Updated 2026-11-01
Structures involved
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Why it happens
- Dysplasia and carcinoma in situ
- Radiation and cancer: ultraviolet and ionizing
- Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk
- DNA repair
- Skin: epidermis layers, dermis, hypodermis
What it is
A common premalignant lesion of sun-exposed skin made of atypical keratinocytes confined to the epidermis. It is a marker of chronic UV damage and can progress to cutaneous squamous cell carcinoma.
Who gets it
Very common in older fair-skinned adults with lifelong sun exposure; risk is higher near the equator and at high altitude, as in Andean Colombia, and in outdoor workers such as farmers. Each individual lesion has a low yearly chance of becoming cancer, but people often have many.
Causes
- Cumulative ultraviolet (UVB) radiation causing mutations, notably in the TP53 gene of keratinocytes
- Immunosuppression allowing atypical cells to persist
- Human papillomavirus may play a cofactor role
Risk factors
- Fair skin, light eyes, red or blond hair, tendency to burn
- Older age and male sex
- Outdoor work, high altitude or tropical sun exposure; tanning beds
- Organ transplant recipients and other immunosuppressed people
- Previous skin cancer; genetic conditions such as xeroderma pigmentosum and albinism
Pathophysiology
UV light induces TP53 and other mutations in basal keratinocytes, which then proliferate with atypia in the lower epidermis. When atypia involves the full thickness it is squamous cell carcinoma in situ, and once cells breach the basement membrane the lesion becomes invasive squamous cell carcinoma. Surrounding skin shows field cancerization, with many subclinical lesions.
Classification
- Clinical: hypertrophic (thick), pigmented, atrophic, and actinic cheilitis (lip)
- Olsen grading: grade I (felt more than seen), II (moderately thick), III (very thick or hyperkeratotic)
Symptoms and signs
- Rough, sandpaper-like scaly papule or plaque, often easier to feel than to see
- Skin-coloured, pink, red or brown, usually under 1 cm
- On face, scalp (bald), ears, lips, back of hands and forearms
- Background of sun damage: wrinkles, freckles, telangiectasias
- Sometimes itching, stinging or tenderness
- Actinic cheilitis: dry, scaly lower lip with blurred vermilion border
Diagnosis
- Clinical
- Clinical diagnosis by appearance and palpation on chronically sun-exposed skin; full skin examination to look for other lesions and skin cancer.
- Tests
- Skin biopsy when the lesion is thick, painful, growing, bleeding or does not respond to treatment, to exclude squamous cell carcinoma.
- Imaging
- Not needed. Dermoscopy shows a red pseudo-network (strawberry pattern) on the face.
Differential diagnosis
- Cutaneous squamous cell carcinoma (in situ or invasive)
- Superficial basal cell carcinoma
- Seborrheic keratosis (stuck-on, waxy)
- Discoid lupus and psoriasis
- Lentigo maligna (pigmented forms)
Goal of treatment
Remove individual lesions and treat the damaged surrounding field to lower the risk of squamous cell carcinoma, plus long-term sun protection and skin surveillance.
Treatment
- Procedure
- Cryotherapy with liquid nitrogen for isolated lesions; curettage or excision for thick lesions or when cancer is suspected.
- Medical
- Field therapy for multiple lesions with topical 5-fluorouracil, imiquimod or diclofenac gel.
- Procedure
- Photodynamic therapy (a topical photosensitiser activated by light) or chemical peels and laser resurfacing for extensive field damage.
- Lifestyle
- Daily sunscreen, protective clothing and hats, avoiding midday sun and tanning beds.
- Follow-up
- Regular skin examinations, more frequent in transplant recipients and people with many lesions.
Complications
- Progression to cutaneous squamous cell carcinoma
- Local skin irritation, scarring or pigment change after treatment
- Recurrence and new lesions in the damaged field
Prognosis
Individual lesions may regress, persist or progress; the risk of becoming squamous cell carcinoma per lesion is low but rises with many lesions and immunosuppression. With treatment and sun protection the outlook is excellent.
Prevention
- Sun protection from childhood: shade, hats, clothing, broad-spectrum sunscreen
- Avoid tanning beds
- Skin checks in high-risk groups such as outdoor workers and transplant recipients
Test yourself
Think of the answer, then tap the question to see it.
Which skin cancer can develop from an actinic keratosis?
Cutaneous squamous cell carcinoma.
What gene is classically mutated by UV light in actinic keratosis?
TP53.
What is the typical texture of an actinic keratosis on palpation?
Rough, scaly and sandpaper-like, often felt before it is seen.
Which field therapy is commonly used for multiple actinic keratoses?
Topical 5-fluorouracil (also imiquimod, diclofenac gel or photodynamic therapy).
When should an actinic keratosis be biopsied?
When it is thick, indurated, painful, growing fast, bleeding or not responding to treatment.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Actinic keratosis: Overview (American Academy of Dermatology, 2026).
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