☀️ Actinic Keratosis (Solar Keratosis) — a common precancerous lesion in older adults with chronically sun-damaged skin.
Regular review is important because a small proportion can progress to squamous cell carcinoma (SCC).
🧠 About
- Also known as solar keratosis or senile keratosis.
- Represents an early stage of SCC development within epidermal keratinocytes due to cumulative UV damage.
- Common in fair-skinned individuals with a long history of sun exposure.
🌞 Aetiology
- Chronic ultraviolet (UV) radiation exposure — particularly UVB — causes DNA damage and keratinocyte dysplasia.
- Acts as an early manifestation of squamous cell carcinoma (in situ).
- UV exposure causes mutations in tumour suppressor genes (e.g. p53).
⚠️ Risk Factors
- Fair skin, blue eyes, red or blonde hair (Fitzpatrick I–II skin types).
- Chronic outdoor occupation or recreational sun exposure (farmers, sailors, builders).
- Tanning bed use.
- Organ transplant recipients or immunosuppressed individuals.
- Older age, male sex, smoking.
🔍 Clinical Features
- Lesions occur on sun-exposed sites — scalp, face, ears, neck, dorsal hands, and forearms.
- Typically erythematous, scaly macules or papules with a rough “sandpaper” texture.
- May appear hyperkeratotic, pigmented, or horn-like (cutaneous horn).
- Usually asymptomatic but may itch, sting, or become tender.
- Multiple lesions may coalesce into larger plaques (“field change”).
🧪 Investigations
- Primarily a clinical diagnosis based on appearance and distribution.
- Biopsy if diagnosis uncertain or lesion enlarges, ulcerates, or becomes indurated (to exclude SCC).
🔎 Differentials
- Bowen’s disease: squamous cell carcinoma in situ — full-thickness epidermal atypia.
- Squamous cell carcinoma: invasive, firm, ulcerated, or rapidly growing lesion.
- Basal cell carcinoma: pearly rolled edge with telangiectasia.
- Seborrhoeic keratosis: “stuck-on” appearance with a waxy or verrucous surface and sharp demarcation.
💊 Management
- Prevention: daily sunscreen use, protective clothing, and smoking cessation.
- Cryotherapy: liquid nitrogen for isolated lesions (destructive method).
- Curettage with cautery for thicker or resistant lesions.
- Topical therapies:
- 5-Fluorouracil (Efudix) – antimetabolite inducing apoptosis of dysplastic cells.
- Imiquimod – immune response modifier.
- Diclofenac 3% gel – anti-inflammatory option for multiple thin lesions.
- Tretinoin – keratolytic retinoid.
- Photodynamic therapy (PDT): suitable for field treatment of multiple lesions, especially on face/scalp.
📚 References
- NICE CKS: Actinic Keratosis (2023)
- British Association of Dermatologists (BAD) Patient Information Leaflet: Actinic Keratosis (2022)
- Marks R. “Epidemiology of actinic keratosis and squamous cell carcinoma.” J Dermatol 1996;23(11):782–789.
💡 Teaching tip:
Actinic keratoses are markers of cumulative UV damage — treat the lesion but also manage the field.
Emphasise lifelong sun protection and regular skin self-examination to catch malignant transformation early.
