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Allergic contact dermatitis to topical prodrugs used in photodynamic therapy
Author(s) -
Cordey Helen,
Ibbotson Sally
Publication year - 2016
Publication title -
photodermatology, photoimmunology and photomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.736
H-Index - 60
eISSN - 1600-0781
pISSN - 0905-4383
DOI - 10.1111/phpp.12252
Subject(s) - photobiology , dermatology , medicine , university hospital , unit (ring theory) , library science , family medicine , psychology , computer science , botany , mathematics education , biology
To the Editor, Topical photodynamic therapy (PDT) is a well-established treatment for actinic keratosis, Bowen’s disease and superficial basal cell carcinoma, and its use has also been explored for a variety of other indications (1–3). Treatment involves application of a prodrug [either 5-aminolevulinic acid (ALA) or its methlyester, methylaminolevulinate (MAL)], which is preferentially taken up by dysplastic or neoplastic cells and converted into the active photosensitizer protoporphyrin IX (PPIX). Subsequent activation of PPIX by red light results in the production of cytotoxic oxygen species, inflammation and relatively selective diseased tissue destruction. A degree of erythema, oedema and crusting is to be expected during and after photodynamic therapy, although this is usually a localized phototoxic reaction with a predictable time course. A far less common adverse effect is the development of a more severe dermatitis reaction as a consequence of contact allergy to the prodrug used. This phenomenon has previously been described in case reports and case series (4–6), but is not widely documented and we report our experience in the Scottish PDT centre.