Clinical Description of Actinic Keratosis
Actinic keratosis presents as discrete or confluent erythematous, scaly patches or papules on chronically sun-exposed skin, with a characteristic rough, sandpaper-like texture on palpation that often precedes visible changes. 1
Primary Clinical Features
Appearance and Texture
- Erythematous, scaly patches or papules are the hallmark presentation, ranging from flat to slightly raised lesions 1, 2
- The lesions have a rough, gritty texture on palpation that is often more prominent than the visual appearance, with this tactile finding frequently preceding visible changes 1, 2
- Classic presentations include thin, adherent scales on an erythematous base, though hypertrophic variants may show thick, adherent keratotic scale 2
- The underlying erythema distinguishes actinic keratosis from seborrheic keratosis, which has a "stuck-on" appearance 3
Distribution Pattern
- Lesions occur exclusively on chronically sun-exposed areas including the scalp (particularly areas of hair loss), face, ears, neck, dorsal aspects of arms and hands, and lower extremities 4
- The "H-region" of the face, lateral neck, décolleté, and dorsum of hands are particularly common sites 2
- Actinic cheilitis is the specific term for lesions appearing on the lips 2
- Multiple lesions often present in a "field cancerization" pattern with both visible and subclinical lesions in contiguous sun-damaged areas 5
Patient Demographics and Context
Typical Patient Profile
- Fair-skinned individuals (Fitzpatrick phototypes I and II) are predominantly affected 6, 5
- Lesions are typically absent in early decades of life unless genetic or environmental factors predispose to increased UV damage 4
- Prevalence increases dramatically with age: 19-24% of individuals over 60 years, and over 70% of dermatology clinic attendees by age 70 1
- Men are more commonly affected (49%) compared to women (28%) by age 70 1
Risk Factor History
- Chronic occupational or recreational UV exposure is the primary risk factor 2, 5
- History of unprotected sun exposure, particularly in outdoor workers 5, 7
- Personal or family history of skin cancer increases likelihood 7
- Immunosuppression predisposes to higher rates of lesion development and progression 4
Diagnostic Approach
Clinical Diagnosis
- Diagnosis is made primarily through inspection and palpation on clinical grounds 1, 2
- Dermoscopy enhances diagnostic accuracy and provides additional diagnostic information 1, 2
- Documentation should include location and thickness grading at diagnosis 1
When to Biopsy
- Reserve biopsy for uncertain diagnoses or when invasion is suspected (hypertrophic lesions, induration, ulceration, or treatment failure) 1, 2
- Biopsy serves both diagnostic and therapeutic purposes in uncertain cases 1
Clinical Significance
Malignant Potential
- Actinic keratoses represent in-situ squamous cell carcinomas with risk of progression to invasive disease 2, 5
- Progression risk varies from less than 0.1% to 20% per individual lesion, with over 60% of squamous cell carcinomas showing adjacent contiguous actinic keratosis histologically 4
- The presence of actinic keratoses indicates increased risk for developing skin cancer, making treatment associated with lower overall skin cancer incidence 4