Actinic Keratosis

Actinic keratosis appears as an ill-defined red-yellow rough patch or papule with adherent scale distributed in sun-exposed areas such as the head, neck, and back of the hands. It is commonly found in a background of other signs of photoaging, such as solar elastosis and lentigines. Actinic keratosis is considered a pre-malignant lesion in which precancerous cells are restricted to the epidermal layer. It is caused by sun damage, specifically exposure to ultraviolet light. It is more common in light skinned persons, and the incidence increases with nearness to the equator.

With what can actinic keratosis be confused?

Actinic keratosis must be distinguished from other growths, including: seborrheic keratosis, squamous cell carcinoma, superficial basal cell carcinoma, and Bowen's disease (in situ squamous cell carcinoma)

How is actinic keratosis diagnosed?

A history of sun exposure, either recreational or occupational, is usually elicited. The patient will often be fair-skinned and may report a history of skin cancer. The lesion can be difficult to discern and can often be more easily appreciated by touch as a rough scaling patch. Biopsy is usually unnecessary but may sometimes be required to rule out malignancy.

See: Pathology: Actinic Keratosis

How is actinic keratosis treated?

Actinic keratosis can be destroyed with liquid nitrogen cryotherapy. For numerous widespread lesions, 5-fluorouacil (5-FU) cream (Efudex) applied for several weeks will result in an inflammatory reaction and subsequent crusting and destruction of the lesions. Aldara (Imiquimod) is another option. Normal skin has only a minor reaction to 5-fluorouracil. The use of 5-FU results in an unsightly appearance for days to weeks but is very effective. Repeat treatments may be required. Chemical peels with trichloroacetic acid (TCA) can also be used to treat large areas.

Sun protection and avoidance is mandatory. It prevents new lesions from forming and may hasten the resolution of existing lesions. Sunscreen with an SPF of at least 15, avoidance of midday sun, and protective clothing are all necessary.

Buy Discounted Drugs

What is the prognosis for actinic keratosis?

Without treatment, some lesions spontaneously resolve. This is more likely to occur with the adoption of sun-protective measures. As a pre-malignant lesion, some (estimated to be less that 0.1% per year) develop into squamous cell carcinoma. Actinic keratoses continue to develop over time in previously sun damaged skin. Repeat treatments with 5-FU or removal of isolated lesions with cryotherapy will continue to be required. Surveillance is necessary. Cryotherapy can result in scarring.

What's new in actinic keratosis?

An association has been suggested between squamous cell carcinoma and human papilloma virus, specifically species 2 members of the genus Betapapillomavirus. Members of this virus family have also been found in low amounts in actinic keratosis. (J Gen Virol. 2008 Oct;89(Pt 10):2467-74)

Image links