TY - CHAP M1 - Book, Section TI - PHOTOSENSITIVITY, PHOTO-INDUCED DISORDERS, AND DISORDERS BY IONIZING RADIATION A1 - Wolff, Klaus A1 - Johnson, Richard Allen A1 - Saavedra, Arturo P. A1 - Roh, Ellen K. Y1 - 2017 N1 - T2 - Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology, 8e AB - The term photosensitivity describes an abnormal response to sunlight. Cutaneous photosensitivity reactions require absorption of photon energy by molecules in the skin. Energy is either dispersed harmlessly or elicits chemical reactions that lead to clinical disease. Absorbing molecules can be: (1) exogenous agents applied topically or systemically, (2) endogenous molecules either usually present in skin or produced by an abnormal metabolism, or (3) a combination of exogenous and endogenous molecules that acquire antigenic properties and thus elicit a photoradiation-driven immune reaction. Photosensitivity disorders occur only in body regions exposed to solar radiation (Fig. 10-1). SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1140790072 ER -