Cumulative skin damage is caused by repeated exposure to the ultraviolet light found in sunshine. Areas with high exposure such as the scalp (bald individuals), forearms, face, and back of the neck are common sites. Over the years, the genetic material of cells becomes irreparably damaged and produces lesions like these on the scalp. The lesions, called actinic keratosis, 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.