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Photodermatoses - Skin diseases induced by light: An overview
Photobiology Unit, Ninewells Hospital, Dundee DD1 9SY, Scotland, UK
The photodermatoses form a group of conditions induced or aggravated by sunlight. Essentially these are subdivided into the idiopathic (possibly immunologically mediated) conditions, namely, polymorphic light eruption, actinic prurigo, solar urticaria, juvenile spring eruption, hydroa vacciniforme and chronic actinic dermatitis. Drug and chemical induced photosensitivity is subdivided into photoallergy and phototoxicity. Other diagnostic groups include the porphyrias, the genophotodermatoses and the photoaggravated disorders. It is undoubtedly the case that polymorphic light eruption is the commonest of the photosensitivity disorders. This condition, which arises particularly in young women, can persist for the majority of life. Essentially when a patient has one of the idiopathic photodermatoses, they are restricted to the natural history of that disease and its management.
Other photodermatoses are, in comparison, relatively uncommon. Photocontact dermatitis, whether due to photoallergy or phototoxicity is an important diagnosis to make. To label an individual as an endogenous photodermatosis when identification of an allergen an enable preventative medicine, is an unsatisfactory outcome of a visit to the clinic. Key photodermatology investigations are phototesting, including provocation testing, photopatch testing, porphyrin and lupus analysis. The genophotodermatoses require careful laboratory cell mutation studies to define whether a disorder is due to an abnormal helicase or DNA repair function.
Having obtained the diagnosis, the natural history, prognosis and therapeutic options come into play. Each condition has its own particular therapeutic aspects. While milder forms can be managed with simple photoprotective regimes, the more severe quality of life disabling conditions may need our most potent immune suppressive therapies. During this lecture, individual diagnoses and their investigative findings will be discussed.
Lim HW, Honigsman H, Hawk JLM, eds. Photodermatology. New York, Informa Healthcare USA, Inc., 2007.
© James Ferguson (text) and Radoslaw Spiewak (source code).
This page is part of the website photopatch.eu (contact).
Document created: 12 August 2009, last updated: 13 August 2009.