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actinic (solar) keratosis (AK)

Single or multiple, dry, rough, scaly lesions that occur on sun-exposed skin of adults. Etiology: 1) prolonged & repeated sun exposure in sensitive individuals 2) damage to keratinocytes by UVB radiation Epidemiology: 1) middle aged individuals 2) incidence 50% of white Australians > 40 years of age 3) fair-skinned individuals, almost never in blacks or East Indians 4) more common in males 5) common in individuals who work outdoors Pathology: 1) precursor lesion to cutaneous squamous cell carcinoma 2) abnormal cells confined to epithelium 3) spontaneous regression occurs in up to 25% of lesions 4) 1:1000 lesions/year convert to squamous cell carcinoma Clinical manifestations: 1) adherent hyperkeratotic scale, but may be papular 2) color: yellow-brown to brown, often with reddish tinge 3) rough like coarse sandpaper; may easier to palpate than visualize [2] 4) generally round or oval < 1.0 cm, ~ 2-3 mm [2] 5) lesions bleed easily when picked off, but recur 5) distribution: sun-exposed skin, sparing of nasolabial folds 6) generally asymptomatic, but slight tenderness may occur * images [8,9] Differential diagnosis: - discoid lupus erythematosus - keratoacanthoma - squamous cell carcinoma Complications: - precursor lesion to cutaneous squamous cell carcinoma Management: 1) prevention a) UVA/UVB sun screens applied daily to sun exposed skin b) sunblocks (zinc oxide) applied to highly exposed areas, i.e. nose, ears c) clothing & hats 2) cryotherapy with liquid nitrogen - may be followed with topical 5-fluorouracil - useful for a few individual lesions (use 5-FU for many lesions) [13] 3) topical 5-fluorouracil (5-FU) (5%) for several days to weeks a) for many lesions (> 10-15) within a confined area, topical 5% fluorouracil better than imiquimod, photodynamic therapy, ingenol mebutate or cryotherapy [13] b) may leave patient extremely uncomfortable with > 4 week recovery period c) pulse dose therapy: BID application 2 consecutive days per week for 3 months produces less inflammatory response 4) imiquimod (Aldara) [3,5] a) apply twice a week for 4 months b) apply at night, wash off after 8 hours c) 50% complete clearance of 4-8 AKs [4] d) clearance correlates with erythema [4] 5) tirbanibulin (Klisyri) 1%: apply once daily for 3-5 days to face or scalp [14] 6) masoprocol (Actinex) 7) Solaraze (topical diclofenac 5%) [3] 8) ingenol mebutate (Picato) 9) excisional biopsy of lesions: a) > 5 mm in size b) nodular lesions c) thick, indurated papules d) rapidly growing lesions e) bleeding lesion f) itching or painful lesions [2]

Related

keratoacanthoma (KA)

General

keratosis premalignant skin lesion

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, 18. American College of Physicians, Philadelphia 1998, 2012, 2018. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  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: 15837864
  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: 16557235
  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#: 280306 (subscription needed) http://www.prescribersletter.com
  8. Actinic keratosis (image) American Academy of Dermatology https://www.aad.org/public/diseases/scaly-skin/actinic-keratosis
  9. DermNet NZ. DermNet NZ (images) http://www.dermnetnz.org/lesions/solar-keratoses.html
  10. Rigel DS, Stein Gold LF The importance of early diagnosis and treatment of actinic keratosis. J Am Acad Dermatol. 2013 Jan;68(1 Suppl 1):S20-7. PMID: 23228303
  11. Gilchrest BA, Martin G. Pitfalls of evidence-based medicine: the example of actinic keratosis therapy. Arch Dermatol. 2012 Apr;148(4):528-30. PMID: 22508879
  12. Siegel JA, Korgavkar K, Weinstock MA. Current perspective on actinic keratosis: a review. Br J Dermatol. 2017 Aug;177(2):350-358. Review. PMID: 27500794
  13. Jansen MHE, Kessels JPHM, Nelemans PJ et al. Randomized trial of four treatment approaches for actinic keratosis. N Engl J Med 2019 Mar 7; 380:935-946 PMID: 30855743 https://www.nejm.org/doi/10.1056/NEJMoa1811850
  14. Blauvelt A, Kempers S, Lain E et al Phase 3 Trials of Tirbanibulin Ointment for Actinic Keratosis. N Engl J Med 2021; 384:512-520. Feb 11 PMID: 33567191 https://www.nejm.org/doi/full/10.1056/NEJMoa2024040