Actinic keratosis
Also called solar keratosis, AK
Sun-induced dysplastic keratinocyte patches: rough, gritty, scaly macules on chronically exposed skin, often felt before they are seen. A field-damage marker and a (low-rate) SCC precursor.
How it looks
Multiple ill-defined, rough, gritty erythematous macules with adherent white scale over the balding scalp and dorsal hands, more easily palpated than seen.
Rose is the lesion, grey the pattern the lesions make, green where on the body it lives.
Across skin tones
AKs are strongly concentrated in fair, chronically sun-exposed skin; they are uncommon in deeply pigmented skin, which shifts the pre-test odds of any rough facial papule.
Symptoms & course
- Rough texture; occasionally tender
- Chronic, on a background of sun damage
Diagnostic approach
- Clinical; biopsy lesions that are thick, tender, or growing
Differential, and how to separate them
- Squamous cell carcinoma
Favours it: Induration, thickness, tenderness, growth
Against it: AKs are flat and rough; hardening means biopsy
- Seborrheic keratosis
Favours it: Stuck-on waxy plaque, not gritty
Against it: AK feels like sandpaper on red skin
Management principles
- Cryotherapy for discrete lesions
- Field therapy (5-FU, imiquimod) for confluent damage
- Sun protection going forward
Clinical pearl: Run your fingertips over sun-damaged skin, AKs are a tactile diagnosis.
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