Makindo Medical Notes

☀️ 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.