title: Immediate and delayed cutaneous reactions to radiocontrast media.
abstract: Hypersensitivity reactions to contrast media (CM) are frequent causes of anaphylaxis and drug exanthemas. Adverse events after CM exposure are classified into immediate (≤1 h) and non-immediate reactions (>1 h), with differing mechanisms. In the majority of patients with immediate reactions, IgE-mediated allergy cannot be demonstrated, and the underlying mechanism remains unknown. However, recent data have provided evidence for skin test positivity and/or specific IgE in some patients. T cell-mediated hypersensitivity is the responsible mechanism for the majority of non-immediate skin eruptions. These insights have consequences for diagnosis and prevention. Skin testing evolves to be a useful tool for diagnosis of CM allergy. Skin tests have been employed to confirm this hypersensitivity. Previous reactors have an increased risk to develop new reactions upon repeated exposure; however, other risk factors are poorly defined. The use of skin tests for the selection of a 'safe' CM is under investigation with promising results. In vitro tests to search for CM-specific cell activation include flow cytometric approaches, lymphocyte cultures and construction of cell lines and hybridomas. Premedication of previous reactors is common practice among radiologists; however, breakthrough reactions are a concern, and physicians should not rely on the efficacy of pharmacological premedication.
authors.affiliation: Department of Dermatology and Allergy Biederstein, Technische Universität München, Munich, Germany. knut.brockow@lrz.tum.de
authors.forename: Knut
authors.initials: K
authors.lastname: Brockow
mesh_terms: D003287:Contrast Media / Q000009:adverse effects*; D004342:Drug Hypersensitivity / Q000145:classification / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D019275:Radiopharmaceuticals / Q000009:adverse effects*; D012307:Risk Factors; D012882:Skin Tests; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D007073:Immunoglobulin E