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Pitfalls in drug allergy skin testing: false–positive reactions due to (hidden) additives
Author(s) -
Grims Robert Hermann,
Kränke Birger,
Aberer Werner
Publication year - 2006
Publication title -
contact dermatitis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 96
eISSN - 1600-0536
pISSN - 0105-1873
DOI - 10.1111/j.0105-1873.2006.00835.x
Subject(s) - medicine , allergy , penicillin allergy , dermatology , patch test , sensitization , drug , drug allergy , penicillin , antibiotics , immunology , pharmacology , chemistry , biochemistry
Skin testing for drug hypersensitivity is a valuable diagnostic tool and a well established procedure for betalactams and corticosteroids. Although appropriate patch, prick or intracutaneous testing usually permits unequivocal interpretation, the possibility of false–positive reactions must be kept in mind. We report two patients, one with a suspected penicillin allergy and one with a suspected steroid allergy, in whom positive skin tests initially yielded a false diagnosis. In both cases, other findings were inconsistent with the positive skin tests. Therefore, further investigations were performed. After the test preparations had been analysed, the skin test was extended to include the additives, which then yielded the diagnosis of sensitization to the surfactant polysorbate 80 (PS 80, contained in the penicillin test solution) and the emulsion stabilizer carboxymethylcellulose (CMC, contained in the steroid preparation), respectively. It should be noted that positive reactions to test solution additives, as in the first case, may lead to a lifelong false diagnosis of (penicillin) allergy, whereas an undiagnosed allergy to additives in parenteral applications, as in the second case, might prove fatal.