For people with actinic keratosis, cumulative skin damage is caused by repeated exposure to all ultraviolet light, including that found in sunshine. Over the years, the genetic material of cells becomes irreparably damaged and produces lesions. The lesions, like those seen here on the arm, may later become cancerous.
Review Date 10/14/2018
Updated by: Michael Lehrer, MD, Clinical Associate Professor, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.