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 the past 5 years, there have been notable strides toward the earlier recognition and discovery of melanoma, including new technologies to complement and augment the clinical examination and new insights to help clinicians recognize early melanoma. However, incidence and mortality rates throughout most of the developed world have risen over the past 25 years, while education and screening, potentially the best means for reducing the disease, continue to be severely underutilized.
Most humans depend on sun exposure to satisfy their requirements for vitamin D. Solar ultraviolet B photons are absorbed by 7-dehydrocholesterol in the skin, leading to its transformation to previtamin D3, which is rapidly converted to vitamin D3. Season, latitude, time of day, skin pigmentation, aging, sunscreen use, and glass all influence the cutaneous production of vitamin D3.