Synopsis
Recognise individual actinic keratoses and field cancerisation, identify possible invasive SCC, choose lesion- or field-directed treatment and support long-term ultraviolet protection and surveillance.
- Actinic keratosis is a rough, sandpaper-like keratotic macule or papule on chronically ultraviolet-exposed skin and may be easier to feel than see.
- Field change means multiple lesions plus background mottling, atrophy and telangiectasia across a sun-damaged anatomical area.
- Biopsy a tender, indurated, rapidly enlarging, bleeding, ulcerated, thick or treatment-resistant lesion to exclude invasive SCC.
- Observation with protection is reasonable for selected thin asymptomatic lesions in lower-risk patients when follow-up and safety-netting are reliable.
- Cryotherapy is lesion directed; topical 5-fluorouracil, imiquimod, diclofenac, tirbanibulin or photodynamic therapy can address a field according to site and licence.
- For 5-fluorouracil 5% cream, a common licensed field regimen is once or twice daily for three to four weeks, with site-specific specialist directions.
- Explain the expected sequence of redness, soreness, erosion and healing before field treatment and supply a stop and contact plan.
- Use shade, clothing, hats and broad-spectrum sunscreen while avoiding messages that imply past ultraviolet damage can be reversed completely.
Key red flags
Induration, tenderness, rapid growth, ulceration, bleeding, a thick cutaneous horn, lip involvement, treatment resistance or immune suppression raises invasive SCC concern and requires urgent diagnostic review.
New pain, induration, rapid growth, ulceration, bleeding or treatment resistance requires urgent biopsy for SCC.
Investigation priorities
Map lesion burden, background damage and any focus suspicious for invasion.
Management branches
A small number of typical thin lesions has no invasive warning and host risk is low.
- Discuss observation versus lesion-directed cryotherapy based on symptoms, site and preference.
- For cryotherapy, obtain consent for pain, blister, pigment change and scar and use anatomy-appropriate freeze technique.
- Review non-clearance or focal thickening and biopsy rather than repeatedly freezing an uncertain lesion.
Key medicines
Fluorouracil 5% creamApply a thin layer once or twice daily to the precisely defined actinic field for three to four weeks, or as directed for the anatomical site.Avoid pregnancy, eyes and mucosa; review severe inflammation, infection and dihydropyrimidine dehydrogenase deficiency risk, wash hands and follow site-specific specialist instructions.