Chronic sun exposure is the cause of almost all actinic keratoses. Sun damage to the skin is cumulative, so even a brief period in the sun adds to the lifetime total. Cloudy days aren’t safe either, because 70-80 percent of solar ultraviolet (UV) rays can pass through clouds. These harmful rays can also bounce off sand, snow and other reflective surfaces, giving you extra exposure.
The ultraviolet radiation given off by the lamps in a tanning salon can be even more dangerous than the sun, so dermatologists warn against indoor tanning.
Occasionally, actinic keratoses may be caused by extensive exposure to X-rays or a number of industrial chemicals.
Because the total amount of time spent in the sun adds up year by year, older people are most likely to develop actinic keratoses. However, nowadays, some individuals in their 20s are affected. Still, actinic keratoses become much more common in people over the age of 50. Some experts believe almost everyone over 80 has actinic keratoses.
Also, individuals whose immune defenses are weakened by cancer chemotherapy, AIDS, organ transplantation or excessive UV exposure are less able to fight off the effects of the radiation and thus more likely to develop actinic keratoses.
Though only about 10 percent of AKs turn into cancers, there is no way to know ahead of time which ones are precursors of squamous cell carcinoma. That is why it is fortunate that there are so many effective treatments for eliminating actinic keratoses.
When an AK is suspected to be an early cancer, the physician may take tissue for biopsy. This is done by shaving off the top of the lesion with a scalpel or scraping it off with a curette. Local anesthesia is required. Bleeding is usually stopped with a styptic agent.