Actinic Keratosis

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Contents 1 Introduction 2 Etiology 3 Epidemiology 4 Pathology 5 Clinical-manifestations 6 Differential-diagnosis 7 Management 8 More General Terms 9 Additional Terms 10 References

Introduction

• Single or multiple, dry, rough, scaly lesions that occur on sun-exposed skin of adults.

Etiology

• prolonged & repeated sun exposure in sensitive individuals
• damage to keratinocytes by UVB radiation

Epidemiology

• middle aged individuals
• incidence 50% of white Australians > 40 years of age
• fair-skinned individuals, almost never in blacks or East Indians
• more common in males
• common in individuals who work outdoors

Pathology

• precursor lesion to cutaneous squamous cell carcinoma
• abnormal cells confined to epithelium
• spontaneous regression occurs in up to 25% of lesions
• 1:1000 lesions/year convert to squamous cell carcinoma

Clinical-manifestations

• adherent hyperkeratotic scale, but may be papular
• color: yellow-brown to brown, often with reddish tinge
• rough like coarse sandpaper; may easier to palpate than visualize [2]
• generally round or oval < 1.0 cm, ~ 2-3 mm [2]
• lesions bleed easily when picked off, but recur
• distribution: sun-exposed skin, sparing of nasolabial folds
• generally asymptomatic, but slight tenderness may occur

Differential-diagnosis

• discoid lupus erythematosus

Management

• prevention

• UVA/ UVB sun screens applied daily to sun exposed skin
• sunblocks ( zinc oxide) applied to highly exposed areas, i.e. nose, ears
• clothing & hats

• cryotherapy with liquid nitrogen - may be followed with topical 5-fluorouracil
• topical 5-fluorouracil (5%) for several days to weeks

• may leave patient extremely unconfortable with > 4 week recovery period
• pulse dose therapy: BID application 2 consecutive days per week for 3 months produces less inflammatory response

• imiquimod ( Aldara) [3,5]

• apply twice a week for 4 months
• apply at night, wash off after 8 hours
• 50% complete clearance of 4-8 AKs [4]
• clearance correlates with erythema [4]

• masoprocol ( Actinex)
• Solaraze ( topical diclofenac 5%) [3]
• excisional biopsy of lesions:

• > 5 mm in size
• nodular lesions
• thick, indurated papules
• rapidly growing lesions
• bleeding lesion
• itching or painful lesions [2]

More General Terms

• skin disease (dermatologic disorder, dermatopathy, dermatosis)
• premalignant skin lesion

Additional Terms

• 5-fluorouracil [5-FU] (Fluoroplex, Efudex, Adrucel)
• masoprocol; nordihydroguaiaretic acid; NDGA (Actinex)
• UV-B radiation

References

1. Color Atlas and Synopsis of Clinical Dermatology, Common and Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 238-39
2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, American College of Physicians, Philadelphia 1998
3. Prescriber's Letter 11(5):27-28 2004
4. Journal Watch 25(11):92, 2005 Korman N, Moy R, Ling M, Matheson R, Smith S, McKane S, Lee JH. Dosing with 5% imiquimod cream 3 times per week for the treatment of actinic keratosis: results of two phase 3, randomized, double-blind, parallel-group, vehicle-controlled trials. Arch Dermatol. 2005 Apr;141(4):467-73. PMID: [1]
5. Hadley G, Derry S, Moore RA. Imiquimod for actinic keratosis: systematic review and meta-analysis. J Invest Dermatol. 2006 Jun;126(6):1251-5. PMID: [2]
6. Geriatric Review Syllabus, 7th edition Parada JT et al (eds) American Geriatrics Society, 2010
7. Prescriber's Letter 19(3): 2012 Actinic Keratoses Treatments Detail-Document#: [3] (subscription needed) [4]
8. National Guideline Clearinghouse Guidelines for the management of actinic keratoses. British Association of Dermatologists ngc-guideline: [5]

actinic (solar) keratosis (AK)