Actinic keratosis represents an early form of squamous cell carcinoma and a variant of non melanoma skin cancer. It appears on chronically sun-exposed areas of the skin. Therefore actinic keratoses are also known as solar keratoses. Actinic keratoses are a very common disease which mostly affect men older than 50 with fair skin phototypes. The incidence ok actinic keratoses is around 50 percent for patients over 60.
Actinic keratoses are reddish to brown macules which show hyperkeratosis and attached scales. On palpation they have a rough surface. They appear on the areas of the skin chronically exposed to sunlight as the face, scalp, décolleté and back of the hand.
Following the chronic UV-damage, actinic keratoses often show a broad spread with clinical and subclinical lesions. This has lead to the term of field cancerisation.
Development of Actinic Keratoses and Risk Factors
Actinic keratoses are undistinctable from the squamous cell carcinoma in the epidermal layer. They are defined to the epidermis but can evolve into an invasive squamous cell Carcinoma. Around 10 percent of Actinic keratoses become an invasive carcinoma.
The biggest risk factor for the development of Actinic keratoses is a longtime exposure to UV. But also other factors as a fair skin photo type are important. Patients with a fair skin photo type are at high risk due to the poor pigmentation and thus poor protection of the skin. Immunosuppression is another major risk factor for the development of Actinic keratoses. Many studies with organ-transplanted patients show an increased risk for this cohort. Organ-transplant recipients show an increase of 100 percent for the development of squamous cell carcinoma.