An 81-year-old man with a more than 10-year history of both premalignant lesions and skin cancer presents to the dermatology clinic with hyperkeratotic patches on his hands and face. He is a farmer and has spent ample time outdoors. On physical examination, multiple hyperkeratotic patches are observed. An erythematous patch on the patient’s right cheek is biopsied.
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Actinic keratosis, also termed solar keratosis, is a neoplastic lesion that commonly arises on fair-skinned individuals with a history of chronic sun exposure. The most common sites of actinic keratoses are the face, scalp, and extremities. The overall prevalence of actinic keratosis in the United States is estimated to be between 11% and 26%.1
If left untreated, actinic keratosis may evolve into squamous cell carcinoma (SCC). Although usually considered to be premalignant, some dermatopathologists argue that all actinic keratosis lesions should be considered low-grade malignancies.2,3 The risk of progression to either SCC in situ or invasive SCC has been reported to be 0.6% at 1 year and 2.57% at 4 years.4
Several histologic types of actinic keratoses have been described such as hypertrophic, atrophic, bowenoid, acantholytic, epidermolytic, lichenoid, and pigmented.5 Dermatopathologists often use the term hyperplastic actinic keratosis when atypical keratinocytes extend to the base of a shave biopsy specimen.
Actinic keratosis may spontaneously resolve, although recurrence is common.6 Because of the link to invasive SCC, therapeutic intervention is generally advocated.
Therapies are divided into ablative or topical treatments.5 The former includes cryosurgery, CO2 laser treatment, and curettage. Effective topical agents include 5- fluorouracil (5-FU), imiquimod, diclofenac, and 5-aminolevulinic acid in combination with photodynamic therapy.5
In 2020 a new topical agent, tirbanibulin, was approved by the US Food and Drug Administration as a treatment for actinic keratosis on the face and scalp.7
1. Salasche SJ. Epidemiology of actinic keratoses and squamous cell carcinoma. J Am Acad Dermatol. 2000;42(1 Pt 2):4-7. doi:10.1067/mjd.2000.103342
2. Ackerman AB, Mones JM. Solar (actinic) keratosis is squamous cell carcinoma [published correction appears in Br J Dermatol. 2006;155(2):500]. Br J Dermatol. 2006;155(1):9-22. doi:10.1111/j.1365-2133.2005.07121.x
3. Anwar J, Wrone DA, Kimyai-Asadi A, Alam M. The development of actinic keratosis into invasive squamous cell carcinoma: evidence and evolving classification schemes. Clin Dermatol. 2004;22(3):189-196. doi:10.1016/j.clindermatol.2003.12.006
4. Criscione VD, Weinstock MA, Naylor MF, et al. Actinic keratoses: natural history and risk of malignant transformation in the Veterans Affairs Topical Tretinoin Chemoprevention Trial. Cancer. 2009;115(11):2523-2530. doi:10.1002/cncr.24284
5. Reinehr CPH, Bakos RM. Actinic keratoses: review of clinical, dermoscopic, and therapeutic aspects. An Bras Dermatol. 2019;94(6):637-657. doi:10.1016/j.abd.2019.10.004
6. Werner RN, Sammain A, Erdmann R, Hartmann V, Stockfleth E, Nast A. The natural history of actinic keratosis: a systematic review. Br J Dermatol. 2013;169(3):502-518. doi:10.1111/bjd.12420
7. Park B. Klisyri ointment now available for actinic keratosis. MPR. https://www.empr.com/home/news/klisyri-tirbanibulin-almirall-ointment-topical-treatment-actinic-keratosis-face-scalp/ Updated February 18, 2021. Accessed February 26, 2021.