An actinic keratosis is a rough, scaly patch on your skin that develops from years of exposure to the sun. It's most commonly found on your face, lips, ears, back of your hands, forearms, scalp or neck. Also known as solar keratosis, an actinic keratosis enlarges slowly and usually causes no signs or symptoms other than a patch or small spot on your skin.
Over time, actinic keratoses may develop into invasive squamous cell carcinoma; according to one study of almost 7000 patients, among the small percentage of actinic keratoses that progress into squamous cell carcinoma, the length of time for this transformation to occur was approximately 2 years.Cells within actinic keratoses (AKs) show characteristic UV-induced gene mutations.Histologically AKs share features with squamous cell carcinoma (SCC).
In 2012, it was estimated that, in Brazil, there would be 62,680 new cases of non melanoma skin carcinomas in men and 71,490 cases in women. These numbers correspond to an estimated risk of 65 new cases for every 100 thousand men and 71 for every 100 thousand women (according to Instituto Nacional do Câncer - INCA [National Cancer Institute].Skin cancers are the most common malignant tumors in Brazil and the United States, where they account for 20%-30% of neoplasms in Caucasians, 2%-4% in Asians, and 1%-2% in Blacks 1.
Photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) or its methyl ester (MAL) is a very effective method to treat actinic keratosis (AK). New developments will contribute to optimization of this treatment modality. This will partly be based on a better understanding of the nature of AKs. Since pain during treatment is a frequent side effect of PDT, new methods of alleviating pain are of high interest, especially when large areas are treated.