DR(E)SS TO ABACAVIR CONFIRMED BY PATCH TESTS
Abacavir hypersensitivity is a potentially fatal systemic adverse reaction that occurs in 2-9% of exposed patients. Symptoms appear during the first 6 weeks of therapy and are similar to DRESS although usually there is no eosinophilia. Studies have confirmed a positive relation with HLA-B*5701, particularly when only cases confirmed by a positive epicutaneous patch test were considered. This HLA allele is now considered an excellent predictor of abacavir hypersensitivity reaction (55% positive predictive value) and it is mandatory to perform a genetic screening before initiating any HIV treatment with abacavir. We report a case of abacavir hypersensitivity reaction, reminding its clinical resemblance with DRESS and pointing out the differences between these two entities, as well as highlighting the importance of HLA phenotyping before beginning treatment with abacavir and the utility of the patch test in confirming this immunologic reaction and studying its effector mechanisms.
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