Actinic keratoses are defined as hyperkeratotic lesions occurring in sun-exposed adult skin, which carry a low risk of progression to invasive squamous cell carcinoma. This risk has been estimated at roughly 1% per annum.
The lesions initially start as telangiectatic capillaries, which go unnoticed by most patients. After this, a well adherent yellow-brown scale forms over the site of the telangiectasia. The scale becomes rougher, thicker and hornier over time. The most common sites of these lesions are in sun exposed areas such as the backs of the hands, forearms and the face. The sides of the neck and upper ear are also common sites of the lesions. Lesions are usually multiple, with most patients not having one but usually 10-20 actinic keratoses.
Risk factors include: