Actinic keratosis

Actinic keratosis (AK) results from sun damage and is believed to be a precancerous lesion that can develop into SCC.15 Although there is debate among healthcare providers regarding the percentage of AK lesions that progress to SCC, the treatment is relatively low risk.

AK typically presents as an erythematous, scaly macule (Figure 9), a papule, or a plaque. AK lesions feel rough or scaly when palpated by the clinician. They can be solitary or multiple. Typically, there are signs of sun damage to the surrounding skin. AK can sometimes be pigmented. Lesions can present on the lip, in which case it is known as actinic cheilitis. Many times, the patient will complain of constant dryness or fissuring of the lips that is not relieved with moisturizers and low-dose topical steroids. In some cases, AK can be subtle and hard to distinguish from a simple patch of dry skin. However, dry skin will resolve after treatment with a topical steroid of appropriate strength and aggressive moisturization. AK will not resolve with topical steroids, although a slight decrease in scaliness or erythema can be noted.


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Figure 9. Actinic keratosis often presents as an erythematous, scaly macule (arrows). 


The diagnosis of AK is typically clinical. However, if there is any doubt regarding whether a lesion is AK, a biopsy should be performed to distinguish the lesion from SCC or a benign condition such as inflamed seborrheic keratosis or an eczematous process.

There are many ways to treat AK. The most commonly used treatment, especially for a solitary lesion, is liquid nitrogen cryotherapy (cryosurgery). Cryosurgery can be painful and leave scars. Patients in whom extensive scarring may occur, who cannot tolerate the discomfort of liquid nitrogen, or who have multiple AK lesions or an area of AK with extensive surrounding sun damage are good candidates for topical field therapy. Treatment modalities for field therapy include prescription topical 5-fluorouracil (5-FU), topical imiquimod, topical ingenol mebutate, topical diclofenac, and photodynamic therapy (PDT). All of these therapies will cause irritation, inflammation, soreness, scabs, and temporary sensitivity to sunlight.

Prevention

When it comes to skin cancers, the saying, “an ounce of prevention is worth a pound of cure,” holds true. Even better than detecting a skin cancer is preventing one. Screen all patients for actinic exposure and risk factors. Counsel patients on the proper use of sunscreen and sun-protective clothing and, when possible, on avoiding the sun during the hours of peak exposure. Regular daily use of a sunscreen with a sun protection factor (SPF) of 15 or higher reduces the risk for developing skin cancer by 40% to 50%.16 In addition, ensure that patients who are at high risk for skin cancer undergo full-skin screening examinations with a dermatology provider on a regular basis.

Patients who have had a skin cancer are likely to develop additional skin cancers. Patients with a history of SCC have a 50% chance of developing another skin cancer within the first 5 years.17 In 40% of patients with a BCC, a second BCC will develop within 5 years.17 Because of the relative ease of treating some skin cancers, patients (and providers) can forget that patients with a history of any skin cancer require regular full-skin examinations. The dermatology provider will help determine the frequency of recommended skin examinations based on the patient’s history and risk factors.

Abby A. Jacobson, MS, PA-C, is an assistant professor at Thomas Jefferson University in Philadelphia, and a dermatology physician assistant at Family Dermatology of Reading, PA.

All images were provided courtesy of Tania Cohen, PA-C, MPAS, Hyde Park, N.Y.

References

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All electronic documents accessed May 27, 2016.