Actinic keratosis (AK), also known as solar keratosis, is a common skin lesion that develops from years of sun exposure. It is a disorder of epidermal keratinocytes, the main cells in the outer layer of skin, induced by ultraviolet (UV) light. While not a cancer itself, understanding AK’s characteristics and its potential progression is important for skin health.
Identifying Actinic Keratosis
Actinic keratosis presents as a small, rough, or scaly patch on the skin, often feeling like sandpaper to the touch. These lesions can vary in color, appearing pink, red, tan, or even skin-colored. They commonly range from 2 to 6 millimeters in diameter but can grow larger.
These patches develop on areas of the body that receive long-term, cumulative sun exposure. Common locations include the face, ears, lips, scalp (especially in balding individuals), neck, chest, forearms, and the backs of the hands. The primary cause of actinic keratosis is extensive exposure to ultraviolet (UV) radiation from the sun or indoor tanning beds, which damages skin cells. Risk factors for developing AK include fair skin, a history of frequent sunburns, older age, and a weakened immune system.
The Connection to Squamous Cell Carcinoma
Actinic keratosis is considered a precancerous condition, meaning it can develop into cancer. While not every AK lesion progresses, they are direct precursors to squamous cell carcinoma (SCC), a type of skin cancer. The risk of a single AK lesion progressing to SCC is low. However, the risk can be higher for patients with a prior history of non-melanoma skin cancers.
It is challenging to predict which specific AK lesion will progress to SCC, as some may persist or even regress on their own. The vast majority of squamous cell carcinomas originate from actinic keratoses. Because of this potential for malignant transformation, dermatologists recommend treating AKs as a preventative measure. Early detection and treatment can significantly reduce the risk of progression to invasive skin cancer.
Treatment and Prevention
Several professional treatment options are available for existing actinic keratoses, chosen based on the number, location, and extent of the lesions. Cryotherapy, which involves freezing the lesion with liquid nitrogen, is a common method for individual spots, causing the affected tissue to blister and fall off. Topical creams or gels containing medications like 5-fluorouracil, imiquimod, diclofenac, or tirbanibulin are often prescribed for widespread or numerous lesions, working to destroy the abnormal cells. Photodynamic therapy (PDT) is another option, involving the application of a light-sensitive chemical to the skin, followed by exposure to a special light that activates the chemical to destroy the AKs. Surgical procedures, such as scraping (curettage) or laser therapy, are also used to remove lesions.
Preventing new actinic keratoses from forming involves consistent sun safety practices. Applying broad-spectrum sunscreen with an SPF of 30 or higher daily, and reapplying every two hours (or more often if swimming or sweating), is a primary recommendation. Wearing protective clothing, such as wide-brimmed hats, long-sleeved shirts, and sunglasses, helps create a physical barrier against UV radiation.
Avoiding peak sun hours, typically between 10 a.m. and 4 p.m., also reduces exposure. It is advisable to consult a doctor or dermatologist for any new, changing, bleeding, or painful skin spots, as early evaluation can lead to timely diagnosis and intervention.