Actinic keratosis (AK) is a very common skin lesion. Although AKs are not malignant, about 0.1% to 0.6% will transform to squamous cell carcinomas,1 which are troublesome to treat. What is not known is whether all AKs should be treated and, if so, which of all the available treatments for AKs should be used.
There is ample evidence that AKs are premalignant, and p53 and p16 tumor suppressor mutations are found in both AKs and squamous cell carcinomas.2 In one study, AKs were contiguous to primary lesions in 44% of 22 cases of metastatic squamous cell carcinoma.3 Other studies of the relationship between AK and squamous cell carcinoma found that 82.4% of 165 squamous cell carcinomas occurred with concomitant AKs; 26.7% arose within AKs, and 55.7% arose in close proximity to AKs.4
Lebwohl M. Actinic Keratosis. JAMA. 2016;315(13):1394-1395. doi:10.1001/jama.2016.3065